Classroom training manual. Ultrasonic testing

NASA

CLASSROOM

TRAINING

Prepared

HANDBOOK

under

Contract

Convair General

c:

<

- ULTRASONIC

NAS 8-20185

CR 61228

TESTING

by

Division

Dynamics San Diego,

Corporation Calif.

:

i

for NATIONAL

George

C.

Marshall

AERONAUTICS

Space

AND

Flight

SPACE

Center

ADMINISTRATION

N68-28790 (ACCESSION

GPO CFSTI

ff 653

PRICE

$

PRICE(S)

$

Hard copv

(HC)

Microfiche

(MF)

July 65

NUMBER)

2

(PA_s)

..

(NASA CR Ol_ TMX OR AD NUMBER)

c77,g/ 2
(CATEGORY)

PREFACE

Classroom training

Training

Handbook

handbooks

designed

of Nondestructive of those Ultrasonic

for

Testing.

persons

who

Testing

- Ultrasonic

formal

classroom

material

that

NASA's

programs

Vols.

is not

failure.

This

approach

to Nondestructive

A major with

share

NASA,

These

are

each

requirement

scheduled

of the

other the

piece

technical

George

C.

Huntsville, The

recipient

and

comments

Space

Flight

Huntsville,

before

Space

Center, Alabama

instruction Handbook

time,

this

-

of only

small

handbook

Testing. quantities

of

extreme in reliability for could result in mission

necessitates

a thoroughly

disciplined

for

assuring

or

and contractor monitor

the

it is committed

concerning Flight

such tests

to its

The

decision

this

publication

Center,

Quality

high

levels

of reliability

Nondestructive that must

Testing

ultimately

mission.

should

or reject

is no room --

for

unquestionably

be referred

and Reliability

personnel.

confirm

There be right

lies

to the

Assurance

Laboratory,

35812.

of this for

portions

in the

Instruction

present

requiring the of one article

reliability

reexamination.

questions

Alabama

exercise

in Nondestructive

procurement

agehcies,

who conduct for

Marshall

complete

at the

engaged

equipment, The failure

responsibility

of hardware

of

Testing.

Government

people

error -- no chance the first time.

General

for

of a series

be used

Programmed

scheduled

to personnel

space vehicles and ground support the first as well as later models.

practical

handbook

completed

training

tightly

and

this

is one

I-III).

is beneficial

involve

(5330.18)

classroom that

successfully

(5330.13,

contains

in the

It is intended

have

Although

use

Testing

handbook

correction Quality 35812.

is encouraged of errors and

to submit

in this

Reliability

initial

Assurance

recommendations compilation Laboratory

for

to George

updating C.

(R-QUAL-OT),

Marshall

--

ACKNOWLEDGMENTS

This handbookwas prepared by the Convair Division of General Dynamics Corporation under NASA Contract NAS8-20185. Assistance in the form of process data, technical reviews, andtechnical advice was provided by a great many companies and individuals. The following listing is an attempt to acknowledgethis assistance andto express our gratitude for the high degree of interest exhibited by the firms, their representatives, and other individuals who, in many cases, gave considerable time and effort to the project. Aerojet-General Corp. ; Automation Industries, Inc., Sperry Products Division; AVCO Corporation; The Boeing Company; Branson Instruments, Inc. ; The Budd Co., Instruments Division; Douglas Aircraft Co., Inc.; General Electric Co. ; Grumman Aircraft; Dr's Joseph & Herbert Krautkramer; Lockheed Aircraft Corp. ; Magnaflux Corp. ; The Martin Co. (Denver); McDonnell Aircraft Corp. ; North American Aviation, Inc. ; Pacific Northwest Laboratories, Battelle Memorial Institute; Division St. Corp.

ii

Louis

of Almar-York Testing

Company,

Laboratories,

Inc. Inc.

Rohr

; Uresco,

Corporation; Inc.

; William

Pioneer

Industries,

Southwest

Research

C.

X-Ray

Hitt;

Institutt Products

CLASSROOM

TRAINING

ULTRASONIC

MANUAL

TESTING

CHAPTER

1 .......................................

INTRODUCTION

CHAPTER

2

.........................................

PRINCIPLES

CHAPTER

3 .........................................

EQUIPMENT

CHAPTER

4

.........................................

CHAPTER

5

............................

CHAPTER

6

.............................

CHAPTER

7 .............

TECHNIQUES CALIBRATING CALIBRATING COMPARISON

AND

SELECTION

TESTING

UNITS

TRANSDUCERS

OF NDT

PROCESSES

iii

r

I

CHAPTER TABLE

!

i

i

|

OF

CONTENTS

Page

100

GENERAL

........................................

1-3

I01

PURPOSE

........................................

1-3

102

DESCRIPTION

OF

1. 2.

.................................... ......................................

!

!

INTRODUCTION

Paragraph

!

|

1:

!

Arrangement Locations

103

INDUSTRIAL

104

TESTING

105

PERSONNEL

106

TESTING

107

TEST

PROCEDURES

108

TEST

OBJECTIVE

CONTENTS

APPLICATIONS PHILOSOPHY

...........................

OF ULTRASONIC

................................

....................................... CRITERIA

1-3 1-3 1-3 TESTING

.........

1-4 1-4 1-4

..................................

1-4

..................................

1-4

...................................

1-5

p?_ECEDiNG

PAGE

BLANK

NOT,

CHAPTER 100

complexity

cedures

that

ment.

and

101

this

vehicles

(testing

number

dictate

without

test

is concerned,

and testing

associated

destroying)

of nondestructive

handbook

and

fabrication

ground

provides

procedures

is widely

pro-

support

many

available,

equip-

of these ultrasonic

used.

PURPOSE

The

purpose

testing that

of this

required the

of the

results

either

test

is to provide assurance

technique,

finished

of the

retest

handbook

by quality

proper

quality

The

which

programs

of space

testing

Of the with

of space

reliability

Nondestructive

testing,

1.

expense

ensure

procedures.

102

INTRODUCTION

GENERAL

The

the

1:

FILMED.

test;

and

DESCRIPTION

and test

or combination

product;

or assistance

the

interpret,

recognize

fundamental

knowledge

personnel

to enable

of techniques,

evaluate, those

and

areas

in interpretation

and

them

is used

make

of doubtful

of ultrasonic ascertain

to assure

a sound test

to: decision

results

that

the as to require

evaluation.

OF CONTENTS

ARRANGEMENT material

contained

in this

handbook

is presented

in a logical

sequence

and

consists

of: a.

Chapter

1:

Introduction

b.

Chapter

2:

Ultrasonic

The

testing

testing

applications

2.

and

principles

and

Chapter

3:

Equipment

d.

Chapter

4:

Testing

e.

Chapter

5:

Calibrating

testing

f.

Chapter

6:

Calibrating

tran

g.

Chapter

7:

Comparison

first

paragraphs,

page

with

description

of procedures,

capabilities

c.

LOCATOR

philosophy

techniques

and

units

sduc er s selection

of NDT processes

S of each

figures,

chapter and

tables

consists are

of a table listed

in each

of contents table

for

the

of contents.

chapter.

Major

103

INDUSTRIAL

Because

of the

of both

metallic

tubing,

plastics,

cally

APPLICATIONS

basic

quality

assurance

basic

of space

and

testing,

such

Since

it is one

as welds,

ultrasonic

discontinuities

materials,

it is used

testing

(variations

in material effective

a variety

castings,

is capable

of the

most

to test

forgings,

sheet,

of economi-

composition) tools

in a

available

to

PHILOSOPHY

reason

for

use

associated

accomplish

etc.

TESTING

personnel.

TESTING

The

products

ceramics,

subsurface

of dissimilar

of ultrasonic

nonmetallic

and

revealing

104

characteristics

and

variety

OF ULTRASONIC

such

of nondestructive ground

reliability,

testing

support

is to assure

hardware,

standards

have

fabricated

been

set

maximum of many

and test

reliability

materials.

results

To

must

meet

these

be trained

and

highly

NASA standards. 105

PER SONNE L

It is imperative qualified under

with test

equally tests

that

personnel

a technical

must

for

understanding

(specimen),

qualified.

responsible

and the To

test

make

optimum

keep

abreast

continually

of the

ultrasonic test

equipment

procedures. use

Ouality

of ultrasonic

of new

testing and

materials,

assurance testing,

developments.

the

personnel

personnel

There

item

must

be

conducting

is no substitute

for

knowledge. 106

TESTING

When

required

be tested

by appropriate

using

of a building individually are

tested

this

approach,

possible 107

CRITERIA

block

test

before

they

individually

TEST

review

formation

available

of personnel

1-4

required

before

they

are

dictates required

and

that

each

item

are

must

be tested sub-assemblies

at the

reduced

must

is part

in assemblies.

discovered and

article

criteria

and

to perform

reliability

support The

in assemblies,

articles

system

vehicle techniques.

to perform

and faulty in higher

for

ultrasonic

testing

history,

experience

of past

concerning

similar

conducting

performed,

to be incorrect for

which

are

every Testing

Using earliest

cost.

PROCEDURES procedures

vision

philosophy

resulting

specimen,

adequately

Nondestructive

unsatisfactory

time,

Approved

bility

documentation,

applicable

and

or inadequate

correction

and

or checking that

the

must

incorporation

test

are

formulated on like

specimen tests

into

from similar

to ensure to the

that

attention procedure.

of the

It is the test

is accomplished.

revised

analysis specimens,

discontinuities.

objective

be brought

or

in-

responsi-

procedures Procedures

of responsible

test

and are

found super-

4mmmm, 108

TEST

OBJECTIVE

b l,

means

2.

The objective of:

of ultrasonic

a.

Obtaining a visual under test.

b.

Disclosing

the

c.

Separating determined

acceptable standards.

No test

Evaluation

recorded

nature

is successfully

of test

testing

procedures

image

of the and

related

discontinuity unacceptable

completed and

is to ensure

results

until

product

by providing

to a discontinuity

without material

an evaluation

requires

reliability

impairing

in the

the

in accordance

of the

understanding

test

specimen

material. with

results

of the

a

test

pre-

is made. objective.

| |

! i =

1-5

CHAPTER 2: PRINCIPLES TABLE OF CONTENTS

Paragraph

Page

200

GENERAL

201

ENERGY

202

WAVEFORMS

......................................

2-5

203

EARLY

TESTS

.................................

2-6

204

WAVE

.................................

2-6

205

PIEZOELECTRICITY

.................................

2-7

206

SOUNDBEAM

207

TIME/DISTANCE

208

OSCILLOSCOPE

DISPLAY

209

OSCILLOSCOPE

OPERATION

210

........................................ MOTION SONIC

GENERATION

RELATIONSHIP

2-7

.........................

2-8

..............................

2-8

............................

2-I 0

2.

Sweep

Delay

....................................

2-I 1

3.

Sweep

Length

....................................

2-11

4.

Range

Markers

5.

Summary

212

WAVE

215

.............................

General

211

214

REFLECTION

2-5

i.

SOUNDBEAM SOUNDBEAM

213

2-5

...................................

.......................................

General

2. 3.

Comparison Shear and

4.

Transducer General

2.

Mixed

3.

Shear

4.

Surface

2-13 2-14 2-16

MODES

General

2.

Shell's

............................ .............................

...............................

2-17

....................................... of Longitudinal Surface Waves Beam AND

2-i and Shear Wave ............................

Angles

MODE

Wave

....................

2.

First

3.

Second

4.

Calculation

2-19 2-19

Generation

.............................

2-21

............................

...................................... ...................................... Calculations

2-22 ............................ ...................... ......................

....................................... Critical

Angle

Critical

Angle

of Critical

2-21 2-21 2-22

3. Typical Problem-Solving Method CRITICAL ANGLES OF REFRACTION General

2-19

2-20

Generation

7

2-17 2-18

.............................

.......................................

i.

..........

Conversion

Wave

Law

Modes

...........................

CONVERSION

....................................... Mode

5. Summary SNELL'S LAW I.

2-12

FREQUENCIES VELOCITIES

REFRACTION I.

..................................

.......................................

TRAVEL

i.

2-I0

2-22 2-23 2-23 2-23

...............................

2-23

..............................

2-25

Angles

2-25

.........................

2-1

TABLE

OF

CONTENTS

(CONT)

Paragraph

Page

216

SOUNDBEAM

ATTENUATION

217

SOUNDBEAM

SPREADING

I.

General

2.

Beam

3.

Soundbeam

218

RAYLEIGH

219

LAMB

220

General

2. 3.

Lamb Lamb

Spread

2-27

..............................

2-28

..................................

2-28

.....................................

Wave Wave

2-29 2-29

Types ................................ Modes ...............................

2-30 2-30

......................................

i.

General

2.

Acoustic

3.

Reflected

Energy

4.

Couplant

Selection

2-31

....................................... Impedance

2-31

..............................

2-32

................................

2-32

...............................

OF TEST

General

SPECIMEN

2-32

ON SOUNDBEAM

............

2-32 2-32

......................................

Surface

Roughness

...............................

Shape

or Contour

of Test

Mode

Conversion

Within

Coarse

Grain

Orientation RESONANCE

Particles

i.

General

2.

Material

Characteristics

3.

Standing

Waves

4.

Thickness

5.

Summary

2-32

Specimen Test

2-32

....................

Specimen

Within

and Depth THICKNESS

Test

.................

of Discontinuity MEASURING

Specimen

•

•

J

°

•

•

•

°

Wave

Figure

2-2

Ultrasonic

Wave

Figure

2-3

Soundbeam

Reflection

Figure

2-4

Time/Distance

Figure

2-5

Typical

Figure

2-6

Typical

Figure

2-7

Sweep

Delay

Figure

2-8

Sweep

Length

Figure

2-9

Range

Markers

Contact Tube

Adjustment Adjustment

.

•

°

.

°

•

•

•

•

2-37

2-39 2-6

.........................

2-7

.............................

Measuring

Cathode-Ray

•

2-38

............................

Generation

Ultrasonic

,

2-38

............................

Generation

•

2-37

......................................

Sound

2-36

2-37

.................................

2-1

2-36

..................

...........................

Calculations

2-35

.............

.......................................

Figure

2-2

2-27

.......................................

INFLUENCE

222

2-27

................................... Patterns

WAVES

COUPLANTS

221

2-26

.......................................

WAVES

i.

........................... .............................

2-8

.......................... Test

Display

..........................

2-9 .................

2-9 2-10

...........................

2-12

...........................

2-13

..................................

2-14

TABLE

OF

CONTENTS(CONT)

Paragraph

Page

Figure

2-10

Pulse-Echo

Figure

2-11

Longitudinal

Figure

2-12

Figure

2-13

Longitudinal and Mode Conversion

_aear Wave Modes .................................

Figure

2-14

Normal

Beam

Figure

2-15

5* Incident

Figure

2-16

1st

Critical

Figure

2-17

2nd

Critical

Figure

2-18

Calculation

Figure

2-19

Beam Spread in Steel Soundbeam Radiation

Figur

e 2-20

Unit, Wave

Incident

Diagram

Mode

Beam

2-15

............................

2-17

Compared

.............

.............................

2-18 2-19 2-20 2-20

Angle

................................

2-21

Angle

................................

2-22

of Refracted

or

......................

................................

Figure

2-21

Rayleigh

Figure

2-22

Symmetrical

Figure

2-23

Figure

2-24

Irregular Convex

Figure

2-25

Concave

Figure

2-26

Mode

Conversion

Figure

2-27

Dead

Zone,

2-28

Standing

Figure

Block

Surface

Angle

........................

2-24

.............................. Patterns ........................

2-28 2-29

Waves

..........................

& Asymmetrical

Back Surface

Surface Effect

Surface

Effect

Waves

...............

2-31

Effect ........................ .............................

2-33 2-34

.............................

2-34

Caused

Near

Waves

Lamb

2-30

Zone,

by Beam and

Far

Spread Zone

................

...................

..................................

2-35 2-36 2-38

V

Table

2-1

Ultrasonic

Table

2-2

Critical

Table

2-3

Table

2-4

Critical Angles, Contact Testing ...................... Lamb Wave Modes ................................

Velocity Angles,

Differences Immersion

....................... Testing

....................

2-16 2-26 2-26 2-31

V

V

_ECEDING

.BLANK

PAGE

NOT

CHAPTER 200

2:

PRINCIPLES

GENERAL

Ultrasonics ear.

may

Normal

second per

FILMED.

be defined

adults

(16 Kc),

second

speed testing,

may

which

(20 Kc).

of sound

as sound hear

The

frequencies

notes

is about

in air,

with

too high

of frequencies

six

term

a pitch

octaves

middle

is used

used

of 200 thousand

higher

above

suPersonic

and is never

to be detected than

16,000

to 25 million

cycles

C, up to about

to describe

as a synonym

by the human

speeds

per

cycles

greater

for ultrasonic.

cycles

per

20,000

than

the

In ultrasonic

second

are

commonly

used. 201

ENERGY

Sound

is produced

by its

frequency

second.

sound away

each

(F) or the

from that

medium,

a medium.

source.

of the resultant

vibrations oscillate

The

It is the

is moving

pitch

actual

energy,

or cycles

about

their

particles

which

note

is determined

completed

fixed

mean

do not travel

moves

the

in one

particles

positions

in a direcslightly

in

progressively.

WAVEFORMS

If sound

waves

are

tance

is always

wave

to travel

for

The

of complete

up the

through

the

body.

number

making

travels

wave,

202 v

by a vibrating

Particles,

when tion

MOTION

the

by the

measured

the

source

same

from

trough

to trough

and it is known

a distance

of one

to execute

one

as the

complete

complete

or from

crest

wavelength

wavelength, vibration.

to crest,

(k).

The

X, is the

same

The

time

the

dis-

taken

for

amount

velocity

of sound

traveling

through

the

of time

(V) is given

equation: V = _,F

Several

types

of waves

are

possible

with

These are longitudinal, or compression, the same direction as the motion of the the

particle

vibrations

is possible, surface

These

shortest

light.

known

For

objects

absorption. a gas,

this

of light particle

in the At any liquid,

across

as surface are

reason,

ultrasonic

waves,

i.e.,

vibrations

same

manner

surface or another

of the

acting type

angles

shear the

or Rayleigh

wavelengths

to those

High-frequency

with

are

at right

to produce

it ripples

energy

solid

matter.

waves where the particle vibrations are in sound; and shear, or transverse, waves where

in a direction limits,

so that

ultrasonic

similar solid

certain

of a solid

cles.

visible

within

are

sound

may

vibrations are

bundled these

between

the

of the free

of only

"ray'lee")

the

soundbeams

or

The of

properties

focused,

propagated

boundary

It

a few parti-

wavelength

possess

light

sound.

waves.

of the

be reflected,

as a boundary of solid,

along

of magnitude

waves

as directed,

motion

to a depth

(pronounced

wave

or sound

waves

surface

order

they

to the

very

or refracted.

in homogeneous

beams,

with

object

and

are

almost

very

little

an interface completely

2-5

reflected. from

As with

echo-sounding

discontinuities,

vibrations, of the

in liquids

absence

possible

in sonar

enabling

detection

or gases,

are

of shear

rigidity.

applications,

of their

the ultrasonic

presence

propagated

in the

Longitudinal,

pulses

and location.

longitudinal

shear,

Ultrasonic

mode

and surface

echo

only because

wave

modes

are

in solids.

203

EARLY

SONIC

For

centuries,

men

quality

TESTS

difference.

applying struck

kerosene the part

assumed

tested

parts

Around

the

to the part with

pulse-echo and D.

and C.

WAVE

When

a tuning

shown

covering

early

practical

a mallet

the whiting Dr.

deep-seated

immersion

and listening

railroad

men

it with a second where

1940's,

for detecting

first

with

century,

F.

of whiting.

looked

A.

wet,

Firestone

flaws.

testing

coat

for a tonal

inspected

parts

by

Then

they

the part

developed

was the .first

The establishment

of basic

is credited

C.

system

to W.

Hitt

Erdman.

204

compressing

the

them

of this

In areas

In the

instrument

standards

and

a mallet.

to be cracked.

by hitting turn

GENERATION fork the

in Figure

is struck

with a mallet,

air.

These

2-1.

The

waves tuning

it vibrates

travel fork

through

and

air

vibrations

produces

to the

soon

die

ear

sound

of the

waves

by

listener

out and no longer

as

produce

MALLET 'LISTENER

STRONGER WAVE TUNING

Figure waves.

Similarily,

excites

a transducer

from to the with

2-6

the

transducer

front the

test

surface piece,

in ultrasonic (crystal) then

travels test the

::

2-1.

Sound Wave

testing, which

of the with

WEAKER WAVE

FORK

soundbeam

a short

vibrates

through piece.

Generation pulse

as did the

a couplant, Figure pulses

2-2

of electrical tuning

which shows

traveling

the

current

fork.

may

The

be water,

transducer,

through

the

hits soundbeam oil,

etc.,

in contact piece.

or

4.

VIBRATING TRANSDUCER ULTRASONIC

WAVES

\ TEST ELECTRICAL

Figure 205

practice,

electric"

crystal.

press.

'_ The

The

first

refers the

Wave

or oil,

object

with

test

206

Generation

depending

ways,

they

line

high-frequency

strike

may

tube

(CRT)

Ultrasonics

the reflection.

This

knowledge of the flected as echoes from 2-3

Within

ray

factors,

react

in the

when

current the

a coupling

vibrations

other

vibrated,

electric

to

energy

medium,

density

"ease."

is applied

propagate

the

does

is deduced

the

they

discontinuity that

the

time

reflect

crystal,

they

as a vertical

most

are

give

such through

as the

and elasticity

from

several

is received required

the

construction. and the back before

for

type

the

the

back

soundbeam

For

soundbeam cases,

of

into

example,

energy. by the

electrical

of a horizontal

information factors,

as light.

in most

transformed This

direct

way of the

or,

deflection

or oscilloscope. not

same

up by a second,

test piece material and its from both the discontinuity

the

shows

object,

be picked

and presented

on a cathode

Figure

then

or transducer. amplified,

echo

vibrations

an interrupting

"A-Scan."

The

among

through

and

REFLECTION

reflections

crystal again,

on,

a crystal,

transforms

pulsed

"pie"

"to

material.

In many These

them These

to a "piezo-

meaning

words

an electric

then

pulses word

the

whereby

when

crystal

transmits

material.

a Greek like

phenomenon This

and

test

electrical

from

be pronounced

conversely,

vibrates.

vibrations

a speed

should or

applies

is derived

to a reversible

into the

SOUNDBEAM

when

transmitter

"plezo"

current,

crystal

mechanical

water

prefix

two syllables

an electric

crystal,

Into

the

Ultrasonic

a high-frequency

Piezoelectricity produces

the

2-2.

PIEZOELECTRICITY

In actual

the

PIECE

PULSE

trace

same energy

or base

of presentation

is called

about

nature

most

the

exact

important

being

Ultrasonic waves surface of the test reflection to travel

of a

are repiece.

is received. through

the

test

TEST

PIECE

\

I

TRANSDUCER

\

BACK SURFACE_

DISCONTINUITY

Figure

2-3.

Soundbeam

Reflection

piece to the discontinuity and back is only 2/3rds of the time soundbeam to reach to the back surface and return. 207

TIME/DISTANCE

The

one-way

measured pulse

or main

for

CRT

bang

and

from

the

pips)

from

the horizontal

The

that longer

main

the

time

or interface

sion, the

be seen

number

208 Figure

of units

shows

the oscilloscope

above

superimpose surface appeared

2-s

the

an echo

on the

time

and

distance

that

traveling two sharp

line

on the

initial

pulse

for

the

to a reflecting In Figure through

rises

The

farther

the

The

left

echo

side from

be

illustra-

(usually

screen. on the

can initial

in this

or indications

appears

measurements screen

in one-way

water

oscilloscope

the

surface

2-4.

called

precise

of the

screen.

a discontinuity

screen.

the oscilloscope

involved

to travel as shown

is received,

right

are

base

distance

line

related. may

In later

be adjusted

discusto match

(as shown).

DISPLAY

a typical to the

grid

ultrasonic Notice

the initial just

produce or base

to the

illumination,

pip on the

waves screen,

(soundbeam

occurs,

before

screen.

screen in relation and back surface. In the

bang

OSCILLOSCOPE 2-5

echo

trace

earlier,

it will

soundbeam

surface

appears

As mentioned

the

reflecting

the

the

or oscilloscope

tion) instant

distance

RELATIONSHIP

distance on the

and

the position

actual

positions

the

indications

pulse marked

to the right

contact

or front "4. "

of the grid

test of the

of the

The

piece

pip "1."

the resulting

display

indications

or pips

front

oscilloscope on the

discontinuity,

marked

and

displayed

test

on the surface

setup

surface,

screen grid

without These

marked

on on the

discontinuity,

were "0"

adjusted and

the

adjustment,

adjustments

were

accom-

to back

_,

TIME

INITIAL PULSE

FRONT SURFACE

)

Jl

OFPLATE II (ECHO)------71

ROUND TRIP TIME (4 UNITS)

PLATE

OSCILLOSCOPE

SCREEN

Figure

------b.

IMMERSED REFLECTOR IN GLASS BEAKER

2-4.

Time/Distance

PLATE

Measuring

TIME INCH SCALE 0

1

2

3,

I

I

I

1

TEST SURFACE

_j

SPECIMEN

FRONT SURFACE

PULSE) FRONT (INITIAL

BAC K SURFACE

DISCONTINUITY

IL. 1

2

3

TRANSDUCER (DISCONTINUITY LOCATED ABOUT 1-1/4 INCHES WITHIN PART) OSCILLOSCOPE

Figure

SCREEN

2-5.

Typical

Ultrasonic

Contact

Test

Display 2-9

plished by varying two controls LENGTH or RANGE. 209

the SWEEP

DELAY

and

the SWEEP

OPERATION

OSCILLOSCOPE

1.

on the instrument,

GENERAL

The oscilloscope displays ultrasonic similar to a television picture tube. its

electron

is made

gun. The

compounds sistence.

vary

The

determined,

these

glass,

glows screen

be considered phosphor

and behind

then the

similar electrons

emits ceases screen

to the are

or bottle

constructed

with

in composition at the

may

nozzle.

tube

is coated

A phosphor

operation

filament,

screen

directed

produced

electronic

of specially-tested

display.

trons

This

indications on a cathode ray tube (CRT) Figure 2-6 shows a typical cathode ray

and produces from

the

to

various light

to writing a definite

glow.

At the

filament

electron

in an ordinary

accelerated

and bunched

at one

brightness,

when

time The light

to form

HORIZONTAL DEFLECTION PLATES (PRODUCE HORIZONTAL SWEEP)

shapes.

for

the

and

time

of the tube, are

elec-

a water

which

electrons

emitted

GLASS

TUBE

is the

spray

is preare

from

By electromagnetic

a beam

per-

The

its persistence

electrons

picture

by high-speed with

It

Phosphor

of the tube.

of glass

bulb.

end

colors,

period, end

and

compound.

bombarded

on a sheet opposite

gun.

sizes

a phosphor

gun in the base

for

in the

In many

a screen

called

electron

similar light

with

a material

to produce

comes

which is tube and

size

a hot means,

of a pin-

BASE CONNECTORS

ELECTRON

V PIPS

ELECTRON GUN

FOCUS AND ACCELERATION (PRODUCE ELECTRON BEAM)

VERTICAL DEFLECTION PLATES (PRODUCE VERTICAL SWEEP)

VIEWING SCREEN

HORIZONTAL SWEEP LINE

Figure 2-10

2-6.

Typical

Cathode-Ray

Tube

head

when

altered

it strikes

by changing

In ultrasonic when

screen

the

right

be seen

screen.

along

the

equals

The line

appear front

surfaces,

DELAY

control

to be shifted

used,

to allow

In Figure initial

2-7,

the

time and

required

speed and

the

to the

vertical

deflection

relays

surface

this

is known,

pip The

signals appears

spacing

beam

time

The

oscilloscope

plates,

causing

reflected

from

and

between

left

the

by speed may

be

from

the

a pip to the

back

these

to

distance

sweep

to the

to

across

multiplied

horizontal

first

reaches

from

known.

of

too fast

of light

to move

are

edge

speed,

a line

line

or base

the left

as the high

draws

is relayed

to the operator

to shift

pip is moved

to the far

that

2-7

picked pip. left,

the distance

left

shows

base

under

first

permits

or to the the

material

discontinuity

Notice

instrument

right Figure

the

SWEEP

beam

time,

speed

soon

beam.

sweep

from

at a very

a signal

of the to the

operator

the and

view.

zero

As

edge

is

horizontal

the

to sweep

screen

electron

a bright

is called

When

front

constant.

related

pulse)

surface

either

remains

indications

the

shows

speed. left

time

transducer

the

of the

line

on the

pips

test

piece

surface

pip

is a measure

DELAY

SWEEP

indications

since

time later in the sweep, between the surfaces.

SWEEP

on it,

the

hose,

of the

when

time

is applied When

a garden

an electron

When

distance.

line.

back

the

spot

beam

fixed to the

is a measure

zero.

a voltage

and

2.

length

of the

usually

electron

at a certain to return

position

horizontal

the

be determined

from

appears some of the distance

Now

line may

represents

on the

screen This

causes

The

pointing

In operation,

to represent

transducer,

like

oscilloscope

edge

screen.

distance

adjusted

The

right

Distance

screen.

received.

it is caused

on the

right.

3.

the circuit

to the edge,

phosphor direction,

is no signal

An electronic

the

into

the

testing,

there

line.

the

the

test

line

the

side, how the

to the

(see

base SWEEP

right

Figure surface

the SWEEP

the

two pips

control

the is

to see

the

setup).

DELAY, and back has

indications

between

in order

test

pip (which

discontinuity

the first

DELAY

or left

2--5 for

up the front

bringing

and the

the spacing

In adjusting

between

line,

while

is also

the

the front surface

pips

not changed.

LENGTH

that the operator has adjusted the sweep

adjustment must be considered.

delay, the SWEEP

The operator may

LENGTH

wish to superimpose

or RANGE the front and

back surface pips on the oscilloscope grid lines so that the distance relationship on the screen is related to the actual measurements of the test piece. To do this, the horizontal trace or base line is expanded, the pips displayed.

The locations of the discontinuity pip, in relation to the front and

back surface pips, always has the same a.

or contracted, to change the distance between relationship, in proportion, in the test piece.

The expansion or contraction of the base line is away from or toward the left side of the screen.

That is,"ifthe sweep

delay is set so that the start of the

presentation desired is at the leftside of the screen, adjustment of the 2-11

_-_

TIME

---_

OSCILLOSCOPE

TIME

SCREEN

f

FRONT SURFACE SURFACE BACK

RFACE

O

'

1 DISCONTINUITY

[

AFTER ADJUSTING

BEFORE ADJUSTING

Figure SWEEP hand

LENGTH

screen

total

LENGTH

along

In Figure

the

depth

the

entire

part

the SWEEP

depth

across

the

away

stationary. the of the

sweep depth

delay with

from

The

from

In effect,

control,

2-8,

pips

the responses

magnified segment of the part width of the CRT screen. b.

Adjustment

right-hand

depth.

to be moved

Delay

to remain

to view

of the

SWEEP

the

appears

it possible

segment

Sweep

moves

pip which

makes

2-7.

the

delay

sweep test

is adjusted

screen

and to align

desired viewing

with

the

pips

the

to examine

across

to expand

also

the

it possible

the

the

a

entire

view

with

v

left-

in any

allows

segment

the control

In conjunction

makes

LENGTH

delay

piece

control

part. the

or toward

the

of the screen

grids. at

4.

Two

controls,

much

of the

tion,

if not

RANGE

In the previous locating 2-12

the test the

SWEEP

part

DELAY

and

is presented

whole,

of the part

the

at one

SWEEP time

LENGTH

on the

screen

regulate

how

and

por-

what

is presented.

MARKERS example,

the position

the

grid

of discontinuities.

lines

on the Figure

oscilloscope 2-9

shows

screen Range

were Markers,

used

to aid which

in

are

_.P,

TIME

---IP.

TIME

OSCI LLO SCOPE SCREEN

AFTER ADJUSTING

BEFORE ADJUSTING

Figure set

into

tion

the

of any

to fit the the

space

Range the

display

into

convenient are

frequency.

and the

more

the front

Length

line

to aid

the

part.

These

surface

The

higher

back

at a depth

the

are

first

MARKER

MARKER

control

frequency,

measurements.

to the

is located

the

in immediately

the

expanded

surface,

in the

of approximately

switch knob

closer

Assuming

the

identifying

back

as centimeters,

by the RANGE

knob. the

such

Adjustment

markers

pip and

increments,

The

surface

Sweep base

front

controlled

accurate

discontinuity

the part

example

inches,

feet,

(for

on-off

pip,

dividing

etc.

The

function)

selection

spacing

to be

in Figure

as determined

and

of the

of square

is known

shown

5 inches,

or contracted

reflection

permits

the loca-

waves 11 inches

2-9,

the

by the

markers.

5.

SUMMARY

Actually, warm ing,

the

adjustment

marker

the

within

between

MARKER

range

under

discontinuity

space

Markers

from

just

2-8.

the up,

first

concern:

and vertical

brightness

adjustments scale centering.

of the

scale

The

scribed

matter

of personal

choice.

moving

across

screen

the

made,

after

illumination, power

on the

the

sweep

instrument line

ON switch CRT

The

intensity

to form

the

screen. control

sweep

line.

is turned

intensity, usually

contains

This

brightness

determines Sweep

on and

focus,

intensity

to

center-

a control

for

the

is considered

the brightness line

allowed

horizontal

a

of the

is kept

spot

at a 2-13

OSCILLOSCOPE

SCREEN

MARKERS

J_jIRANGE (SET WITH 11 SPACES FROM FRONT TO BACK SURFACE PIPS)

Figure minimum adjust

with the

sharpness

determines the

the

sweep

raises

The

lowers

instrument.

The

A simplified, of the

pulse

or main

is also the

Most These

2-14

vibrations

are

to the

screen.

line

or base

line

Usually, and

the

adjust

and

of each

of a typical illustration The

separated

CRT

many

controls

as shown, transducer

the

Is spiked

In immersion by the

water

travel

scale

the individual

the

testing

timer

the

zero

ultrasonic

for

from

with

the

of various

comes

to place

control

with

manual

the front

set

to coincide

is aligned

ultrasonic

that

control

centering

maintenance

pulse-echo

controls

usually

screen

line

focus

centering

screen,

vertical

instrument

shows

testing,

identical. are

the

operation

CRT

The

on the

and

horizontal

on the

the base

receiver-amplifier.

pips

SOUNDBEAM ultrasonic

of the

In contact

bang

surface

edge

capabilities The

astigmatism The

line

operate

diagram

2-10.

system.

routed

front

210

block

The

sweep

from

precise

in Figure

heart

to"

end.

Markers

presentation.

screen.

learned

Range

of the

left

sweep

on the

left

screen

at the

"how

are

at the

point

the

line

exact

instruments

shown

of the

start

scale

spot

starting

line

and

desired line.

no bright

2-9.

same

source.

instrument

or rate

generator

surface

pip

and the

by an electrical

testing,

the

distance

to the

is is the

initial test

initial

pulse pulse piece.

FREQUENCIES

units are

have far

frequencies beyond

the

available audible

range,

In a range but still

from

200 Kc to 25 Mc.

propagate

in the test

that and

/r

OSCILLOSCOPE

SCREEN

\

RECEIVER AMPLIFIER CIRCUIT

, i

f

\ T SWEEP CIRCUIT

PULSER CIRCUIT

MARKER CIRCUIT

1 I

TIMER (RATE GENERATOR)

i

I

TRANSDUCER

POWER SUPPLY

"

Figure %./

TEST PIECE

(TO EACH CIRCUIT)

2-10.

Pulse-Echo

Unit,

Block

Diagram 2-15

material

as waves

fine-grained

of particle

material.

ference

in the form

be achieved

vibrations.

When

using

of scattering

by using

lower

high

may

They

surface

is rough.

On the

difficult

to resolve

small

beam

with

beams

are

be used

are

a better

be expected.

testing,

longitudinal, vibrational

waves

given largely,

power.

of the

per

to illustrate

is large,

making

a more

All available not

the it

concentrated sound-

frequencies

generally

high-frequency

increase, the wavelength of the molecular or atomic

when

higher-frequency

10 Mc are

thinner

by up to of atten-

can be used

emit

is that

material. of the

may

is governed

may

used

in

transducers.

correspondingly structure.

As

decreases

VELOCITIES travel

through

or die

solids

through

through (ips

For

wide

to differences

range

in the

MATERIAL

sec). and

material.

The

related

to ultrasonic (cm/sec

velocities

In Table elasticity

Ultrasonic

2-1,

These

Velocity

speeds,

mode,

x 100,000

of velocities.

density

2-1.

second

high

of a specific

homogeneous

convenience,

(cm//_

at relatively

velocity

materials per

x 105).

The

a given

various

microsecond the

and liquids

out in gases.

Table

are

testing x 105) given

in each

VELOCITY

(G/CM 3)

CMAuSEC

material,

among

(LONGITUDINAL) MPH

.033

WATER

1. 000

•149

3,333

1.180

.267

5,972

ALUMINUM

2.800

.b25

13,981

BERYLLIUM

1.820 r,,

1.280

of

are

in velocity

0.001

(ACRYLIC)

are

listed

738

28,633

by

per

manual

comparison

Differences

DEN SITY

but

example,

speeds

in this

a meaningful

differences

for

or inches

AIR

PLASTIC

2-16

and

inter-

of penetration

with low frequencies, of the small amount

transducers

above

fragility

depth

of divergence

A disadvantage

Frequencies

in centimeters

x 100,000

centimeters

angle

by coarse-grained

is a constant

authorities

their

material,

frequency

structure

High-frequency

of sound vibrations the dimensions

attenuated

beams because

by a coarse

side,

testing.

because

waves

rapidly

second

more

SOUNDBEAM

Ultrasonic

debit

Greater of test

Ultrasonic material,

penetrate

in coarse-grained

Selection

less

flaws.

resolving

scattered

the frequency and approaches

most

scattered

in immersion

contact

211

also

of all frequencies

frequencies

frequencies.

the nature of the particular problem. about 1 Mc, readily penetrate the test uation.

Soundbeams

are other

in is due,

x.j

factors.

Density

which

is less

almost

WAVE

1.

i

cannot

account

than aluminum. yet mercury

TRAVEL

for the extremely The acoustic

is thirteen

times

high

velocity

velocity

of water

as dense

in beryllium, and mercury

are

as water.

MODES

GENERAL

All materials

I

dense

identical,

212 i !

alone

are

made

up of atoms

(or

tiny particles)

lined

up in straight

lines

to form

lattices, the first

as shown in Figure 2-11. If we strike the side of this lattice, we find that column of atoms strikes the second column, which in turn strikes the third

column,

and

Lion shown. movement

Figure Note

in sequence.

In this

case,

direction.

compression, 2.

so on,

wave

COMPARISON 2-12

shows

This

on the

right

shear

waves

because

motion

produces

particle-movement

type

a wave

direction

of soundwave

motion

movement

is the

is called

same

the

in the

direc-

as the wave-

longitudinal,

or

mode. OF

LONGITUDINAL

two transducers

that the transducer

ducer

the

This

generating

on the left

is producing

& SHEAR

ultrasonic

is producing

a different

the particle-movement

WAVE

kind

MODES waves

longitudinal of wave.

direction

in the

waves These

is at right

same

piece.

and that the trans-

waves angles

are

called

to the wave-

TRANSDUCER/

WAVEDmECTIOM

/

/

WAVE FRONT

.j

Figure

2-11.

Longitudinal

Wave

Mode 2-17

.............

..... -_ ..............

_

-

/TRANSDUCER

/ WEDGE TEST PIECE PLASTIC

I

I

\

I MOTION

I I i I

\ \ SHEAR WAVE

1 LONGITUDINAL

Figure movement

2-12.

direction.

longitudinal

3.

SHEAR

Shear

waves

a plane

Long{tudtnal

The

waves.

wedge so that specific a_le,

WAVE

velocity

Note

also,

that

AND SURFACE in a sense,

right-hand

polarized

to the

direction

erated

in a thin

layer

of particles

waves

are

about

2 per

called cent

Rayleigh less

test

surface As

Compared

is approximately transducer

V

half that

is mounted

specimen.

only

at a sharp

corner.

The

a surface

face

waves

called

angle-beam

contact

=

displacements

A special

free

boundary

type

of the

on a plastic

of a solid.

waves,

and

we_e_:_e

resulting wave

travels

transducers transducers.

around that

oriented

wave

These

propagate

in

is gen-

surface with

a velocity

wh.en a transducer

1o_- itudinal

in a surface

are

of shear

As=sho_in:Ftgure2-13,

plastic

at an angle

shown,

particle

"ray'lee")

shear=waves.

test

are

on the

(pronounced

than

as the

of propagation.

on a steeply:angled the

the

waves

Modes

WAVES

normal

strikes

of shear

Wave

the ultrasonic waves generated by the crystal enter the material at a depending on the velocity of soundbeam travel within the material.

are,

is:mounted

& Shear

mode

beam

of sound

a curve,

produce

in the

shear

wedge

travel

reflection waves

in the occurring

and

sur-

_TRANSDUCER

WEDGE

\

SURFACE

\

D

\

) \

\(j

SHEAR MODE

_

PARTICLE

()

M(]T_N-

,,y/,

() ) ()

/,"

) \

",,/

)

/

NOTE THAT BEAMS ARE IN THE LONGITUDINAL MODEIN EACH WEDGE. MODE CONVERSION OCCURS WHEN THE SOUNDBEAM ENTERS THE TEST MATERIAL.

Figure 4.

TRANSDUCER

Confusion

may

BEAM

ANGLES

be encountered

when

specific refracted rials with acoustic produce

2-13.

angle-beam

angle in cold-rolled velocities different

a shear-wave

beam

Mode

steel, from

Conversion

transducers, for example, that of steel.

at 45 ° in steel,

will

designed are applied A transducer

produce

a beam

to produce

a

to other matedesigned to

at 43 ° in aluminum,

or 30 ° in copper. 213 1.

REFRACTION

MODE

CONVERSION

GENERAL

Refraction one material from

AND

one

and

mode

conversion

to another medium description.

specimen

in the

and

second

and

no refraction

is comparable

to another.

following

When

normal

medium,

of the ultrasonic The

to the entire

a longitudinal

(perpendicular) as shown

in Figure

beam

refraction

range

2-14,

passing

of light

of this

(L) wave direction,

when

phenomena

soundbeam

beams

when

is covered is incident

it is transmitted as a 100-per

at an angle

cent

through longitudinal

from

passing in the to the

test

the first beam,

occurs.

2-19

TRANSDUCER

1ST MEDIUM

TEST PIECE MEDIUM

/

\

(STEEL)

I

I ! I j2 o°

i I

Figure 2.

MIXED

As the

incident

version

occur,

L and

shear

point

MODE

is reached 90 ° and

medium,

where

both

refracted

as the

angle

times

the

incident

is rotated the

(S) wave

between

angle.

beams is known

this

first

as the

critical and

and S-wave

Incident

Refraction -

mode beams

and the and

initial

Beam

"lst

If the

Critical the

Angle.

are

both

produced. beam

conversion

angle angle

TRAN SDUCER---..__

the

in the

more

because

/

1ST MEDIUM

f

(WATER)

the

beam beam

than

a

area

second

in Figure

of each L-wave

conin both

further,

the

As shown

is a little

occurs

'

up:

enters

quantity for

mode

medium,

is rotated

To sum

occur.

and

second

angle

beam

The

refracted

S-wave

"

longitudinal

conversion

refraction

in the

percentages.

the

mode

90 ° position,

is transmitted,

angle,

As shown,

angle,

the beam

of varying

that

is changed.

incident

from

longitudinal

refraction L-

Normal

CONVERSION

angle and

2-14.

varies is four

twice

L-wave

2-15,

the

velocity

--

TEST PIECE 2ND MEDIUM

90 ° (STEEL),_

S-WAVE2 °'...._ O

!_,,..(

L-WAVE

Ii°-._

Figure 2-20

2-15.

5 = Incident

Beam V

changedwhen the beam entered the second medium. The velocity of the shear wave is approximately half that of the longitudinal wave. As the incident angle is rotated further, both refracted angles increase. The first angle to reach 90° will be the L-wave angle, as discussed in the next paragraph. 3.

SHEAR

WAVE

GENERATION

Rotating the transducer to 90 ° , and is reflected

to produce an incident from the test surface,

angle

at the

and

is now positioned only

of the

S-wave

beams

transducer

S-wave

beam

In the

entire

are

increases reaches

the

90",

region,

1st

Critical

transmitted the

between

Angle,

where

through

angle

of the

incident the

angle of 15 ° , the L-wave as shown in Figure 2-16.

1st

the

L-wave

second

refracted

angle and

the

beam

medium.

is positioned

beam.

at the

Angle,

is reflected,

Further

shear-wave

2nd Critical

is increased The incident rotation

When

2nd Critical

only

S-wave

the

Angle.

beams

are

produced. 4.

SURFACE

Rotating

the

creased

to 90 ° .

S-wave

has

face. they

To

to produce

Figure

undergone

these

2-17

waves

an incident

shows

mode

medium,

do not propagate

5.

GENERATION

transducer

In an air

medium,

WAVE

conversion

surface are

that

in a liquid

only

with

Rayleigh

damped

out.

angle

the

some

waves The

are

angle

are

is in-

L-waves;

disturbance

easily

waves

S-wave

waves

particle are

shear

or gaseous

of 27 ° , the

reflected

the

in the

detected;

in the

not reflected

test water

because

medium.

SUMMARY summarize:

where

shear

the waves

critical alone

angles

are

are

transmitted.

TEST

PIECE

those

angles For

bounding

each

points

beyond

those

\; \|

(ST E E L),,,,,,,_

L-WAVE

_ ____/____

I\\

____.

9:0 _'/

S-WAVE

l'J ' SEAM .34.'_X\

\

A Figure

• 2-16.

1st Critical

Angle

side the

of the

area

2nd Critical

sur-

._TRANSDUCER,,_

_'_

27 • L-WAVE

\ TEST

PIECE

\ J

(STEEL)k_k

SURFACE WAVE

\

J 90 °

Figure 2-17. Angle

and

sound

energy

grazing

area

at the

Both

critical

the

2nd Critical angles

soundbeam the

for

other.

is simply

critical

angle

the

the

medium.

sine

surface

of the

words, into

wave

the

type

medium

angle the

in the

velocity L-wave

(in immersion In contact

Rayleigh

by the formula

and second

for

are

known.

second of the

transmitted.

in the

couplant

The

medium, in the

in the Law,

and

the test

specimen.

of 90 °,

the

equation

medium

of

i. e.,

1,

solved

L or S, in the

first

no

angular

if the velocities

sine

and

soundwave,

velocity

being

waves

Snell's

testing), testing,

second

to obtain

the

LAW

the

soundbeam

velocities

material used in contact testing, men, the longitudinal (L) beams when

the

puted

by a formula

1621,

soundbeam a Dutch

fied slightly refraction. 2. The

reflection

second

GENERAL

When

c.

is total

produces

calculated

divided

for

SNELL'S

1.

Angle

are

In other

medium

214

there into the

in the first

is substituted for

incidence,

is transmitted

2ridCritlcal Angle

SNELL'S following

fracted other

2-22

angle, couplants:

enters

the

developed

test

from

mathematician.

from

its

original

used

in immersion

testing,

are different than the sound velocity passing' through the wedge or couplant material. Snell's For application,

use

Incident Law,

after

or refracted Willebrord

in ultrasonics, which

was

Snell's meant

or the wedge

in the test speciare refracted angles

Snell

com-

or Snellius,

Law has

to explain

are been

modi-

optical

LAW CALCULATIONS formula and

the

may mode

be used

to calculate

of materials,

the

including

incident

angle,

solids

immersed

the

resultant

re-

in water,

oil,

or

Sin _1 _ V 1 Sin 92 Where

91 = incident

angle

_2 = angle

NOTE:

of the

V 2 = velocity

of vibrations

calculations

quire

the use

given

in decimal

cm/sec 2.54

for

|

to obtain

2-18 wedge.

As the

second

medium

are

formula the

shows

for

incident

a contact known,

the

shear

case, region

cal

Angle,

where bined 2. As

refracted

FIRST the

fracted the when

waves

CRITICAL

angle

medium.

adjusting

two conditions

subjected

are

The

sine

are

given

or refraction

(abbr:

re-

Sin) ratios

in centimeters To convert

to the right.

are per

cm/_

sec

Multiply

to

in/sec

by

of 35" 30'

soundbeam

beam

is calculated

waves the

angle

of the are

1st and

produced

on a

in the

first

with

the

in the

2nd Critical

and

steel,

as

Angles.

through

For

small

to mode

testing

produced,

angles

between

as is the thus

such

as water

or

when entering a second medium at material under test with a differing

conversion,

region,

a medium

region

lessening

of the resulting

normal

incident

the

confusing

sound-

in a combination

incident

beyond

beam,

and

the

first

critical

signals

from

of

1st

Criti-

angle the

com-

ANGLE

beam

is widened, angle

When

an immersed are

shear

passing

This

for

of incidence

longitudinal

second

refracted

between

2, V2).

waves.

is not as useful

only shear modes.

of incidence

at an incident

velocity

1, V1) are refracted medium is usually the

velocity

and

longitudinal

the

only

soundbeams

2 for

test.

OF REFRACTION

previously,

are

of the

in the

(medium and

angle

In this

plastic (medium 1 for velocity an incident angle; the second beams

and

Law.

GENERAL

velocity

mounted

angle

is fixed

1.

or wedge.

under

handling.

one place

wedge.

METHOD

transducer

incident

ANGLES

easiest

or

cm/sec.

angle

CRITICAL

for

decimal

Snell's

215

As discussed

sec)

PROBLEM-SOLVING

Figure

tables. Velocities

liquid

material.

liquid

material

angles

in the

test

in the

in the

determining

move

in the

vibrations

fractions.

(cm/p

of the beam

beam

of trigonometric

x 10 -5

plastic

normal

refracted

of incident

The

TYPICAL

from

V 1 = velocity

microsecond

3.

V2

considered.

reaches

selecting transducer First,

the

1st Critical 90 ° .

a contact

At this shear

at an incident and

of prime

Angle point, wave angle

is reached only

shear

angle-beam to produce

importance,

is that

when

the

waves

re-

exist

in

transducer,

or

shear

waves,

the

refracted 2-23

!

35°30'f

SNELLIS

LAW: _-SIN _2

SOUND VELOCITY:

/

REFRACTED

VS = VELOCITY

SHEAR

.267

CM//_SEC

STEEL:

V1 =

.585

CM//_SEC

VS = .323

SIN 91

CM/.USEC

= SIN 35°30

' = SIN 0.58070

FROM TRIGONOMETRIC

STEEL

SOLUTION OF PROBLEM FOR LONGITUDINAL

SIN 9_ (0.58070) SIN 92

=

SIN 92

Z-24

LONGITUDINAL

VL =

GIVEN:

V_ .267

CM/_SEC

V L .585

CM/MSEC

WAVES

=

SIN 92

=

Vlr .267

SIN 92

.267

0,58070

1.2723

ALL LONGITUDINAL WAVES ARE REFLECTED; NO LONGITUDINAL WAVE

=

.267

CAN EXIST, IF _2 90" OR MORE.

IS

Figure

Calculation

2-18.

.323

SIN 92

=

SIN 92

=

92

of Refracted

CM/HSEC

VS .32.3 CM/#SEC

SIN 92

.585(0.58070) .267

FUNCTION TABLES.

SOLUTION OF PROBLEM FOR SHEAR WAVES

SIN 91(0.58070)

.585

SIN 92

_2

V 1 = VELOCITY

PLASTIC:

NDBEAM

0.58070

V1 V2

.323(0.58070) .267

0.7024

44°37'FROM TRIGONOMETRIC SINE FUNCTION 0.70236, ONLY SHEAR WAVES ARE PRODUCED BY REFRACTION.

Angle

longitudinal

wave

is totally

reflected

penetrating ultrasound is limited the first condition, the refracted the

requirements

immersion rial

method

at the

3.

in the

waves

are

of surface tests areas 4. If the

incident

shear

standard.

angle

1st

certain

waves

further,

the

reaches

of contact

produced.

must

Critical

that

Angle

the

be 90 ° ) so that

is calculated

soundbeam

testing

with

In immersion to a large

CALCULATION soundbeam

case

the

for

of the

all

piece the

Surface

enters

the of with

in the the

test

when

the

mate-

shear

waves

waves

medium,

medium

have

show units.

are

for

Rayleigh

the

produced

promise

reflected,

surface

dampens

been

re-

production

in experimental

use

in detecting

ANGLES

the

materials

of the

first

and

angle may be calculated with 1, as the sine of the refracted

contact

is reached

in an air

liquid

experiments bonded

OF CRITICAL

Angle

point,

test

testing,

degree.

velocities

2nd Critical

90 °. At this

on immersed articles. These of bond failure in metal-to-metal

in the

of refraction

ANGLE

(V 1 and V2) , either critical using the sine of 90 ° , i.e., Thus,

The

to make

angle

beam

case

angle

angle.

CRITICAL

the

fracted

test

of testing

desired

SECOND

Widening and

of the

(its

to shear waves only. Second, within the limits shear wave enters the test piece in accordance

transducer

mounted

second

medium

are

known

the formula for Shell's Law, angle in the second medium.

on a plastic

wedge

for

testing

steel: Sin ¢I

V1

Snell' s Law: V 2 (longitudinal

Sin _2 Sin _1 Sin _2(1. Divide

V 2 into

V 1 = 0. 45641

V 2 is given

with

cm/_

V 2 is again

divided

sec. a.

b.

Table

2-2

water

(couplant)

Table

2-3,

k.J

lists

approximate

2-1,

with

the for

into

testing, either

sec

Critical

Angle. for

critical

first

critical

is less

0. 585 cm/p

velocity

V 1 = 0. 82662

a plastic

exception plastic

1st

soundbeam

as the

angle-beam than

the

approximate

using

lists

velocity

.r

= 27 ° 9' for

is desired,

sec

0000)

0. 267 cm/p

medium wedge

as the

angles

for

is greater the

couplant in the

for

first

the

same

This

than

' for

2nd Critical

wave the

various

test

the

used test

medium test

Angle.

materials,

using

sec).

materials the

velocity

is one for piece.

0. 323

(V 1 = 0. 267 cm/_

is because

S--wave

Angle

in steel:

2nd Critical

(V 1 = 0. 149 cm/p

of uranium.

velocity

= 55o45

angles

If the

a shear

wave)

which

V 2 should

given L-wave

for

uranium.

the

L-wave

be greater

sec),

in Table soundbeam For velocity than

V 1.

2-25

Table 2-2. Critical Angles, Immersion Testing FIRST MEDIUM IS H2O TEST MATERIAL

1ST CRITICAL

BERYLLIUM

(_

2ND CRITICAL (_

VELOCITY(CM/_SEC).

7o

10"

VL=1.280,

VS=.871

14 °

29"

VL=

.625,

VS=.310

15 °

27 °

VL=

.585,

VS=.323

15"

29 °

VL=

.566,

VS=.312

TUNGSTEN

17 °

31 °

VL=

.518,

VS=.287

URANIUM

26 °

51 °

VL=

.338,

VS=.193

ALUMINUM,

17ST

STEEL STAINLESS

302

NOTE:

VL=LONGITUDINALVELOCITY,

Table

2-3.

Critical

VS=SHEARVELOCITY

Angles,

Contact

Testing

FIRST MEDIUM IS PLASTIC TEST MATERIAL

1ST CRITICAL

BERYLLIUM ALUNIMUM,

17ST

STEEL STAINLESS,

NOTE:

216

SOUNDBEAM

High-frequency are

attenuated

This

loss

Scattering size.

attentuation the

energy

2-26

is lost

SEC).

VS=.871

25 °

59 °

VL=

.625,

VS=.310

27 °

56 °

VL=

.585,

VS=.323

28 °

59 °

VL=

.566,

VS=.312

31 °

68 °

VL=

.518,

VS=.287

waves,

by reflection

and

are

is due

(CM/

VS=SHEARVELOCITY

ATTENUATION

frequency

soundbeam

VELOCITY

VL=l.280,

VL=LONGITUDINALVELOCITY,

is proportional

As the

g

18 °

ultrasonic

losses

2ND CRITICAL

12"

302

TUNGSTEN

g

to the most

through

grain

is lowered, a free heat

through

scattering

important

to damping.

travels

passing

at the

volume where where

transfer

without due

grain

in the the the

In damping path

a material, material

wavelength

losses,

to friction

reduced

boundaries

within

and

wavelength

interruption

are

is greater

than

vibrating

material.

one-third

than

is considered

by grain of the

the

or

the wavelength.

is less

attenuation

in power

boundaries, particles.

grain

grain size,

as though where

217

SOUNDBEAM

1.

SPREADING

GENERAL

An ultrasonic Because

beam

of the

linear

travels

short

or straight-sided

approaches

the

nounced

is considered

some from

spread

wave

and

spread

wavelength all

test

projection

diameter

is calculated

from

the

of the ratio of the

divergence shorter, This

of the

where

of the

recti-

the beam

Although

shape is pro-

the

of the transducer,

diffraction At this

center

is its

characteristic

frequencies. face

or spreading.

of the beam

becomes

of the

X/D,

face

little

propagation.

at almost

to originate

very

a characteristic

spreading. Fraunhofer the face of the transducer.

is a function D is the

with

rectilinear

as a straight-sided

to appear

This

As the

of absolute

to be detected

there is always D2/4X distance outward

matter involved,

shape.

ideal

enough

through

wavelengths

soundbeam in reality

causes the beam to spread distance, the beam spreads

radiating

X is the

face

of the

wavelength

transducer.

The

at

transducer.

of the ultrasonic

sine

of the

half-angle

as follows: X Sin q5 = 1.22--

For

example:

Assume

that

D

a 1-inch

diameter

aluminum at a frequency beam is 0. 625 centimeter. What Convert

is the

D to metric

half-angle

system

contact

of 1 Mc.

of beam

by multiplying

The

transducer

is used

on

wavelength

of the

sound-

spread?

inches

by 2.54

to obtain

centimeters.

0,625

Sin _b = 1.22

2.54

Sin @ = 0. 30012 = 17 °28' 2.

BEAM

Beam

spread

quency,

the

larger

the

crystal

at higher

beam

is often

small

as 1/8-inch

depths

the

crystal,

spread.

limited

diameter

Mc.

at various

by the

diameter transducers

A large-diameter

frequencies, the

Also,

frequencies

ducer

25.0

_,

in steel,

greater

1/2-inch

-

SPREAD

of the been are

used

transducer

beam

the

spread

frequencies.

available used.

in Figure

the beam;

is less

at lower

size have

straighter

there

than

is given

For

shallow

at the higher is usually

smaller for

The

contact

the

surface. depth for

At any fre-

the same

diameter

frequencies,

selected

2-19.

crystal, diameter of the

Transducers testing, such testing

the of

transas

3/8-and as 5.0 through

to greater

of material.

2-27

SIN(_

= 1.22

WHERE

-_-

k = WAVELENGTH D = DIAMETER (_ = HALF-ANGLE OF BEAM SPREAD TO HALF-POWER POINTS

/

/

/ POWER POINT

SOUNDBEAM

Figure

2-20

when

lobes

ing.

are

reflected

the

to the

218

WAVES

waves they

on the are

center. neath the

2-28

over

surface

Reflections the

rounded

travel

surface off,

14°25

5.0

.116

8"34'

3/4

1. O

21"52'

16 ° 13'

'

6"25'

9"33'

7"9'

4" 16'

3"12'

OF INTENSITY)

Beam

Spread

in Steel

from may

its

waves

from

edge

they

cracks

only one test

spurious with

The

Lord

down

oscilloscope from the

side

face

edge and

are

are

intensity

(c. 1875)

Rayletgh corner,

they

away

to because

at a distance

discontinuities

screen.

a sharp

Secondary that

resemblance

Rayleigh

or from

or mount-

in amplitude

a rough

in the on the

secondary

of crystal

strongest

reduction

in an earthquake

surface

The

is such

effects.

by

Mc.

diameter

of consequence.

and bear

studied

a 1/2-inch

manner

specimen

a gradual

of a solid

were

by the

of disturbance

reflected

continue

is the

for

Mc to 2.25

caused

of the

axis,

surface

in steel

1.0

effects

beam

central

the

be seen are

spreading

creating

component

of a block the

19"23'

the geometry

of water;

the principal

top face

.259

are

transducer,

is along

waves

2.25

primary

when

of the soundbeam from the axis.

Rayleigh

34 °

is raised

figure

work,

RAYLEIGH

48" 10'

in beam

frequency

considered back

1/2

.581

2-19.

reduction

in the

In practical

beams

the the

shown

3/8

PATTERNS

shows

transducer side

CM

DIAMETER (D) INCHES

1.0

(.707

Figure 3.

TRANSDUCER

FREQUENCY MC

lying waves

but if the

reflected

from just

the be-

traveling edge

at the

on

is

lower

edge,

D = DIAMETEROFCRYSTAL ,_= WAVELENGTHOF ULTRASONIC WAVEIN STEEL O"

O" = 34"

F = 1.0MC

F = 2.25MC

,_. = .581CM

_. = .259 CM

D = 1/2 INCH

D = 1/2 INCH

Figure returning of its almost finger their The

1. Lamb when

point.

are

rounded

off.

over

the

depth

They

waves

also

surface

work. the

travel

travel the

entire

to the waves

of travel

around

so the

screen

are

also

an elliptical

a cube

Rayleigh

surface,

is usually

with

way

a cylinder.

oscilloscope

Rayleigh

surface

Patterns

the

around

a finger

direction

along

Radiation

called

waves

path

while

surface than

particle

motion,

are

of any

moving

no more

if all re-

the

waves

one

as

wavelength. as shown

2-21.

LAMB

WAVES

GENERAL wave

theory

ultrasonic

was waves

Lamb

a predetermined of a sheet

_.J

the

These

by observing

of the

travels

Soundbeam

by touching

traced

surface

along

soundbeam

wavelength.

puted

absorbed

can be easily

in Figure 219

sending

completely

flection

2-20.

to the

edges

_ = 14"

developed travel

waves

velocity

at a given

angle

along

by Horace a test

Lamb

can be generated and

frequency.

of incidence.

(c. 1916).

specimen in thin These The

a thickness

sheets

by using

waves

proper

Lamb

with

are angle

waves

are

comparable

produced to the

longitudinal

waves

transmitted

into

the

of incidence

may

be com-

of

surface

as follows:

2-29

DIRECTI

l

/

PROPAGATION

SURFACE

I

PARTICLEMOTION

Figure

Rayletgh

2-21.

or

Surface

Waves

VL Sin _b Vp V L = Incident

Where

Vp

2.

LAMB

There

are

WAVE

classes

3.

LAMB

In Table duced

Lamb

The

ability

of problems not reveal medium,

the

and

frequency,

types

of Lamb

of Lamb

incident

plate

waves

requiring

angles,

modes

of practical

in Lamb

wave

of frequency,

testing.

Up to an infinity mode propagates and which

waves

are

These

are

of modes of each class with a phase velocity

varies

from

shown

thick

with

the

problems,

sec

plates

infinity

in Figure

down

to

2-22.

their

velocity

near

for

which

plate;

with

them

applicable

pro-

velocity

it is desirable longitudinal higher

close that

velocity are

first

to the

energy

of subsurface modes

to a wide The

is contained

detection the

beam,

a longitudinal

discontinuities.

energy

Where or where

a 5 Mc ultrasonic

of

in water. make

of subsurface

waves. plate,

a phase

aluminum

in thin

since

Rayleigh

along

transmitting

0. 149 cm/_

to flow

defects,

as with

Examples

and

the detection

subsurface

required,

is a function

MODES

in a 0. 051-inch

distance

2-30

Both

in the

siderable

produced

asymmetrical waves. in a given plate. Each

following

waves sec

of waves

thickness

velocity. WAVE

2-4,

0. 635 cm/p

the

on plate

wave

wave phase velocity which and the test material.

TYPES

two general

depends

Rayleigh

velocity.

= Desired Lamb plate thickness,

termed symmetrical and of vibration are possible that

wave

surface

travel

discontinuities are

employed.

useful,

variety

modes

are

do of

a conis

THIN P LATE ,_,,,_

PARTICLE

MOTION

G

I°"ECT'O' PART,CLE MOTION

J

SYMM ETRICAL

Figure

ASYMMETRICAL

2-22.

Symmetrical Table

size 220

Wave

PHASE

VELOCITY

CM//ISEC.

Waves

Modes

MODE

PRODUCED

°

.267

31.0

°

.279

IST SYM.

25.6 °

.335

2ND ASYM.

19.6 °

.432

2ND SYM.

14.7 °

.572

3RD ASYM.

12.6"

.660

3RD SYM.

7.8"

1.067

4TH SYM.

of thin-walled and

2) the

testing

tubing

IST ASYM.

and plates

of welds

for

internal

in butt-welded

defects

plates

and

or grain tubes.

COUPLANTS

1.

GENERAL

One

of the

from

the

tween

_-J

Lamb

Lamb

33.0

inspection

determinations;

& Assymmetrical

2-4.

INCIDENT ANGLE

1) immersed

t

practical source

the

problems into

source

and

surface

of a dry

part,

material

because

in ultrasonic

testing

is transmitting

the

test

specimen.

This

the

test

material.

If a transducer

of the

very great

little

energy

difference

is done

is transmitted in acoustic

the

by interposing is placed through impedance

the

ultrasonic

energy

a "couplant"

be-

in contact

with

the

interface

into

the

at the

interface. 2-31

2.

ACOUSTIC

When

IMPEDANCE

an ultrasonic

wave,

traveling

ary between it and a second medium while the remainder istic

of each

acoustic

test

material

impedance

through

one

material

or medium,

reaches

a bound-

medium, part of the energy continues through the second is reflected back into the first medium. The characterthat

(z) and

determines

the

is a product

of the

amount

of reflection

is known

density

(p) and velocity

(v),

as the

expressed:

z=pv 3.

REFLECTED

In a pulse-echo

ENERGY system

of travel.

If the

the

medium

second

different the

calculated

theoretical

method

impedances

occur

with

medium

with

specimen.

and

ideal.

in each

will

and

result

is with

from

has

lkluid

in a

interface the

roughness

Experience

ff

in water-magnesium

different

as surface

direction

is reflected;

in a water-steel

be vastly

such

to a solid

For with the

that may

to that

of the

oil,

work.

When

that

or minute

shown

that

the

couplants.

water the

some

ideal

Prestone, testing,

is adequate.

of matching

source

and

the

matches

the

impedance

using

bubbles

sugar

transformer wetting

and

test

transformer

soap-suds,

Usually,

of air

into

is an interposed

made

a thin

often

medium

method

of the been

situations one

couplant which

have

benzene, contact

elimination

from

impedances

Experiments For

testing,

the

however,

occurs,

The

as a transducer

glycerin,

to ensure

alike;

be transmitted

is between

amalgams.

immersion

them

must

necessary.

be viewed

water,

various

by keeping

impedance.

couplant

oil or water

solutions,

oil appears

agents

are

to thoroughly

wet

added the

couplant.

INFLUENCE

OF

TEST

SPECIMEN

ON SOUNDBEAM

GENERAL

The

highest

test

specimen

for

evaluating

fiat-bottomed part

be familiar 2-32

material

example,

may

once energy

it is 72 percent,

of reflection.

energy

becomes

an impedance

SAE 20 motor

to the

where

different

This

mercury,

that

For

variables

waves

twice, of the

of interface

reflection

percentage

be matched

a couplant

of the transducer

1.

actual

ultrasonic

testing

of greatly

impedance

221

combination

Many

the

may

in ultrasonic

another

part

an interface 100 percent

COUPLANTSELECTION

Acoustic

oil,

almost

of reflection. the

affect

of coupling

through

is air,

in water-aluminum

reflection.

will

passes each

percentage However,

discontinuities

4.

air,

is 88 percent,

it is 54 percent.

best

wave

medium

is not

theoretical

reflection

the

second

degree

of reliability

variables the

effects

holes, as

a reference with

and

the

in ultrasonic

their

effects

are

of test-specimen

or other

suitable

standard. influence

testing

is obtained

understood

geometry targets,

With

of geometric

and such

and material

the

and considered. material

in one of the

or without

when

test

a standard, variables,

influence

of

A shortcut

properties parts

and the

six

is to drill then

operator in all.

to use must In one

form or another, the operator will receive spurious or confusing indications from any of the following test specimen variables: 2.

SURFACE

Rough

ROUGHNESS

surfaces

distort

Loss

a°

of echo

be due the

and

of resolving echo. lobe

smooth just

loss waves

portions

the

which

within

part

the part.

or to roughness

boundary

is caused

This of the

by a lengthening

as a wide

front-surface

of transducer

side

not reflected

condition

loss

may

surface

on

may

on the

or secondary

back

mask

of the

pip into

the

the

frontoscilloscope

lobe

energy.

transducer

presence

from

of a discontinuity

surface. due to scatter

frequency

OF TEST

where

the

back

surface

transducer. from until

soundbeam

are

of the

shows

to another

the they

front die from

test

a test

surface

specimen

specimen

is parallel

On the

spread

rough

or to a requirement

SPECIMEN

2-23

at an angle

the

scatter.

surfaces

Figure to the

from

to reduce

or contoured area

returned

of the

is seen

This

of beam

reflection.

is sloped one

of the

is normally

OR CONTOUR

In the are

surface from

below

boundaries

surface.

power

by reflection

energy

a lower

SHAPE

of back

as follows:

discontinuities

surface

surfaces.

Widening for

Angular

from

at the

This

is caused

Side

3.

amplitude

to scatter

surface

c.

indications

discontinuity.

Loss

b.

ultrasonic

left

cause with

front

surface,

in the

area

where

sound

waves

surface,

the

attenuation.

reflection

point

or total

an irregular

to the

side,

out from each

partial

the the

are

sound

back

caromed

In actual so that

back

practice,

a few weak

IMMERSED TRANSDUCER

"° I TEST

"__

Figure _o,.J

_

2-23.

SPECIMEN

Irregular

Back

Surface

Effect 2-33

signals

are a°

received

by the

transducer,

creating

confusing

A convex surface is illustrated on the The soundbeam Is widened by refraction boundary.

Considerable

specimen

surface,

acoustic

as shown,

the discontinuity size discontinuity

have less in a flat

test

power

indications.

specimen shown in Figure 2-24. after passing through the convex is lost

and by beam

by reflection

spread.

amplitude than test specimen.

signals

at the

Signals received

test

reflected from

from

the

same

IMMERSED TRANSDUCER

\

Figure b,

Figure

2-25

shows

through

the

concave

discontinuity identify

2-24. a test

signals

because

/RE ECTEO

Convex

specimen

boundary, are

with

the

relatively

of unwanted

Surface

a concave

soundbeam high

reflections

Effect surface•

is narrowed

After

in amplitude,

but may

from

surface.

the

test

IMMERSED =

TRANSDUCER

_

_

It \

•

_,

/ REFRACTED

DISCONTINUITY

•

Figure 2-34

==

SURFACE I / I "W'l WAVE I/ I \1 /

SPECIMEN

2-25.

Concave

Surface

I

A

Effect

"

passing

or focused.

I

be difficult

The to

4.

MODE

When

the

tion

CONVERSION

shape

or contour

of it as in the

mode appear are

slowed

the

at the

by velocity

reflected

culated

test spread,

is not points

conversion

changes

reflection

are

Where:

As the sine

that

the

angle

angle

will

is about

V L = Velocity

of the

longitudinal

beam

V S = Velocity

of the

shear

in the test

angle

of the

longitudinal

beam

of the longitudinal

beam

reflected

beam

of incidence

is equal

to the

half

the

longitudinal

of the

changed

from

Soundbeams

at angles

which

are

cal-

beam.

angle.

beam

longitudinal

velocity

are

waves.

they

= _-S

shear

the

they

will

because

VL

= Reflected

angle

as they

back

Law:

_S

be about

half

reflected

transducer,

If a direct

to appear

when

= Incident

of the

slow

or a por-

to the

be identified are

_L

incident

the

back beam.

to longitudinal

by the

of Snell's

Sin ¢PL

may

echoes

back

soundbeam,

by the

conversion,

then

calculated

equivalent

Sin ¢S

mode

the

reflected

contacted

These

and

that

directly

indications

during

waves

which

is such

boundary

reflection.

to shear

SPECIMEN

specimen

back

at angles

by the

TEST

mode

first

waves

of the

of beam

occurs

is obtained, behind

longitudinal are

case

conversion

reflection

WITHIN

is known,

is equal angle

beam

longitudinal

in the

test

or can be easily

to it,

in accordance

of reflection. angle,

beam.

specimen.

as the Figure

determined, with

The

reflected

velocity

of the

2-26

shows

the shear

shear

rule beam beam

soundbeam

re-

TEST SPECIMEN

TRANSDUCER

S-WAVE DING BEAM

Figure

2-26.

Mode

Conversion

_

Caused

_"_'--

__.,.. L-WAVE

by Beam

S-WAVE_ _

Spread

I /

flections within a long solid test part.

The spreading beam

contacts the sides of the

part with grazing incidence. Depending on the material, the resulting mode consists of mixed modes of longitudinal and shear waves. 5.

COARSE

Coarse

GRAIN

PARTICLES

WITHIN

TEST

conversion

SPECIMEN

or large grain particles within the test specimen

can cause scatter and loss of

back reflection, particularly when the size of the particle and the wavelength are comparable.

If the frequency is lowered to the point where

the wavelength is greater

than grain size, scattering losses are reduced, but sensitivityis also lowered. 6. The

ORIENTATION orientation

result may

and

in the lie

loss

with

proportion

long

to the its

nuity,

is small,

and the

to the Figure

far

shown.

are

zone.

When

leading

edge

surface

within

the

to the test

surface.

2-27 The

depth

trailing

is extended the

to the

dead

zone,

of back three

dead

dead-zone no indication

limit.

LEADING EDGE OF PULSE (EXTENT

_'_ ZONE

I

vary

length

is just

amplitude

FAR ZONE

Figure

EDGE OF PULSE

2-27.

Dead

Zone,

Near

Zone,

and

Far

Zone

pip turned diszone, V

as the

beneath beyond

the the

to a consid-

TEST SPECIMEN

OF DEAD ZONE)

I I

near

specimen,

If it is just echo

of the

the

test

discontinuity

the

of

de-

disconti-

pulse

I

-,,---TRAILING

2-36

of the

be displayed.

will

depth

zone,

by the

surface

the

is probably

by the dead

loss

discontinuity

I

_NEAR TRANS-_ DUCER

the

the

If the

from If the

affected

If the

will

from

in

A sudden

discontinuity

is determined is at the

dead zone, in the near zone, phasing effects erable degree as a function of position.

i

also zones:

zone

pulse

transducer.

surface.

the

are

discontinuity

indication

is angled

by reflections

test

reflection,

the

a small

or may

of a discontinuity.

caused

principal

of the

the

indications

of orientation,

discontinuity

from

to the

confusing

causing

the presence

parallel

of the

edge

case

away

Indications

shows

In the

to the pip

and

loss

cause

If the

indicates

is flat

may

soundbeam,

directed

is proportional

compared

continuity.

echo. to the

discontinuity.

scanning,

discontinuity

at an angle

discontinuity

parallel

of the

when

OF DISCONTINUITY

discontinuity

reflections

in amplitude the

DEPTH of the

axis

size

reflection,

crease

depth

of the

its

soundbeam, back

AND

The

depth

of the

near

zone

transducer diameter, side. At this distance, center

of the

diffraction

(from

a condition

nuity

as the

amplitude

of the

222

RESONANCE

dimension

is sometimes

the beam

near

soundbeam).

where

effect

causes

of the

zone

lines

to spread

varying

indications across

from

the

THICKNESS

may

it.

of the

discontinuity

the

distance

from and

in the

from

near

zone

diminishes

the

transducer

is irregular

be obtained

Beyond

the

to as Fraunhofer

at D2/4_

intensity

from

beam on each originated from

referred

(D = diameter

Soundbeam

is moved

indication

inereases.

the

near

the

same

in the

far

exponentially

zone,

discontizone,

the

as the

dis-

MEASURING

GENERAL

With

the resonance

oscillator

tube,

surface

test

direction

the

sample

resonates

voltage.

the

piece

test

an exact cies.

or oscillates increase

in its

number Thus,

The

Resonance

is maintained

from

the

with

maximum vibration

at one

direction,

where These

to express

the

crystal

of a suitable

the

sample

The

thickness

until

vibration

increase

re-

in its

of vibration sample

of

is equal

resonance

of a material

in

is varied

sample

of the

harmonic

to vibrate

crystal

frequencies

called

thickness

on the

a consequent

resonant

the

of an

and held

of the

with

are

by means

frequency, cause

intensity.

of the

is excited, by means

of vibration

of crystal

T=N N = Any whole

a crystal the crystal's

frequency

wavelengths.

it is possible

Where

contact

occurs

thickness

of half

below

waves

thickness.

in an amplitude

method,

well

Acoustic

Longitudinal

of its

induced

measuring

frequency

piece.

medium.

the sults

thickness at some

of the

coupling

%J

limit

transducer

tance

1.

F

of the

This

which

far

by extending

to intersect with the spreading spreads outward as if it had

face.

optics)

to the

= wavelength causing

as shown, the beam

transducer

transducer,

is determined

to

frequen-

as:

2

number

of harmonics

= Wavelength T = Thickness 2.

MATERIAL

Each

thickness

quency. are

in phase,

nance smooth

frequency

a relatively

Since

resonance

_

of a given

At this

occurs.

CHARACTERISTICS

the

velocity

is an accurate

method and

is used parallel,

material

has

or multiples large

a characteristic of it,

increase

is a known

in the constant,

and

reliable

primarily

for

thickness

but

also

detect

it will

when

measure

or fundamental the

transmitted

amplitude the

of the

frequency

of an unknown measurements

discontinuities

resonant and reflected

waves

required

in the

thickness.

The with

in the

waves material

to produce

of material lying

fre-

same

resotwo sides plane

as

2-37

the

test

surface.

In general,

ing systems.

It differs

ously

The

varied.

material

under

series

point

test

of aluminum

3.

STANDING

Thickness

number

standing

wave

displacement

at which

the

thickness

alloys,

have

is applied

frequency

much

like

of transmission

frequency

matches

determining

factor.

an almost

constant

the

the

other

is,

or can be,

ultrasonic

resonance

Similar

resonant

test-

continu-

point

of the

materials,

such

as a

frequency.

WAVES occurs

of half

The

in test

referred distance

length.

In resonance

opposite

side

material

(T) is equal

to X/2,

T

of the

ultrasonic

wave.

In a standing and

adjacent

there

piece.

TEST

thickness

material.

between

test

the of the

to as nodes

testing,

of the

ll

whenever

wavelengths

patterns are

aatinodes,

the

is the

resonance

integral

resonance

in that

is always

In the 3X/2,

standing

X, and

PIECE

=

is equal

Figure

wave,

the points nodes

material the

points

of minimum

or adjacent

a node

to an

shows

as

is a half

transducer

illustration,

and

the

various

of maximum

displacement

antinodes

at the

wave

2-28

wave-

a node

thickness

at the

of the

2X, respectively. /TRANSDUCER

h

0.5k

T

=_

_--

V

•-,

T

=

=

1.5A

Figure 4.

THICKNESS

Velocity may

is always

be expressed

2-28.

--

Standing

T

=2k

"

Waves

CALCULATIONS equal

to the

product

of frequency

and

wavelength,

thus

wavelength

as: V F

Substituting be expressed

2-38

V _-for as

X in the 2T = N v F"

V equation

T = N, -_

results

in

T

_

NF= 2

N 2_F

which

may

Since

N is any

and thickness known.

whole may

Example:

number

it may

be calculated

In a resonance display, Mc,

if the

sample

velocity

thickness

harmonic

3.31

be disregarded.

Mc,

peaks

4.21

and

test,

resor_ant

a steel

on the

Mc,

and

Mc.

V T = 2"F

frequency

sample

screen

5.11

V 2T = -_-or

Thus

causes

are

a resonant

of the

oscilloscope,

What

is the

at 2.4

thickness

of the

? V

Using

the

equation

T -

where

F = Resonant

2F

frequency

V = 0. 585 cm/_ T = Thickness

in Mc

sec,

velocity

oscilloscope a listing table

determinations

screen, of velocity

is used

(using

T = Thickness

to thickness

a thickness

of constants inch/seconds of the

part

scale

over

the

(called

a K table)

divided

by two.

in inches,

using

which The

the

is

K

equation:

in inches.

in million

T =

inch/second

divided

or Fundamental

by 2).

Frequency).

0. 116 (K for steel) 0.90 Mc

T = 0.128 5.

inches

F

in Mc (Resonant

example:

0.128

K

(veloCity

F = Frequency For

peaks)

frequency)

by placing

in million

of material

K = Constant

0.90

to a table

given

frequency

cm=

made

or by referring

TWhere

between

in steel

1.80

are

constants

to convert

distance

0.585

T = 0.32 thickness

Mc average

(cm) T -

Actual

(0.90

inch

SUMMARY

A variable-frequency ducer.

There,

transmitted

oscillator the

vibrational

energy

amplified,

and

oscilloscope

electrical

continuously

is received

indicated

screen,

into

transmits energy

is transformed

the

test

specimen.

by the

transducer,

on a display an audible

high-frequency

tone,

system. a meter

electrical into

When

mechanical

resonance

transformed This

may

deflection,

energy vibrations occurs,

into

be a trace

to a transand

a surge

of

electrical

energy,

deflection

on an

or a flashing

neon

indicator. 2-39

The greatest accuracy is usually obtained with the oscilloscope display. As the oscillator sweeps through the resonant frequency of the test specimen or through any harmonics of that frequency, vertical indications appear on the oscilloscope screen. These indications are used to determine thickness as they indicate the frequencies required to produce resonance at the fundamental frequency or its harmonics.

V

2-40

V

CHAPTER

3:

TABLE

OF

EQUIPMENT CONTENTS

Page

Paragraph 3O0

GENERAL

301

PULSE-ECHO

3O2

3O3

304

305

306

........................................ UNITS

3-3

.................................

3-3

1.

General

.......................................

3-3

2.

Controls

.......................................

3-3

3.

A-Scan

Equipment

................................

3-6

4.

B-Scan

Equipment

................................

3-7

5. C-Scan ULTRASONIC

Equipment ................................ TANK AND BRIDGE/MANIUPLATOR

1.

General

2.

Ultrasonic

....................................... Tank

.............

3-7 3-9 3-9

..................................

3-10

3. Bridge/Manipulator ............................... TRANSDUCERS .....................................

3-11 3-12

1

General

3-12

2 3

Sensitivity Resolution

4

Materials

5

Crystal

6

Transducer

....................................... ..................................... .....................................

3-12 3-12

...................................... Planes

3-12

..................................

Types

3-13

................................

3-13

7 Frequency COUPLANTS

Selection ............................... .......................................

3-17 3-18

1.

General

.......................................

3-18

2.

Immersion

3. Contact STANDARD

Couplant

...............................

3-19

Couplant ................................. REFERENCE BLOCKS ........................

1.

General

.......................................

2.

Area/Amplitude

3.

Distance/Amplitude

4.

Basic

5.

Special

Blocks

Blocks

Set

Blocks Set

Blocks

..........................

3-20

Set

3-20

.......................

3-21

..................................

TESTING

1.

General

.......................................

2.

Inductance-Modulated

3.

Capacitance-Modulated

4.

Manually-Tuned

5.

Bond

6.

Resonance

Instrument

7.

Transducers

for

8.

Resonance

Tester

3-19

.................................

RESONANCE

EQUIPMENT

3-22 ....................... ......................

Instrument Instruments

.....................

.........................

....................................

Testing

3-24 3-24 3-26 3-26

Indications Reference

3-23 3-23

Instrument

Resonance

3-19 3-19

......................

Testing Blocks

3-27

....................

3-29

....................

3-29 3-1

TABLE

OF

CONTENTS

(CONT)

Paragraph Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure

3-2

3-1 3-2 3-3 3-4 3-5 3-6 3-7 3-8 3-9 3-10 3-11 3-12 3-13 3-14 3-15 3-16 3-17 3-18 3-19 3-20 3-21 3-22 3-23 3-24 3-25 3-26 3-27 3-28 3-29 3-30

Page Typical

Pulse-Echo

A-Scan

Presentation

Unit

.............................

B-Scan

Presentation

..............................

3-8

..............................

3-8

C-Scan

Presentation

C-Scan

Principle

Typical

C-Scan

Controls

of Operation Recording

Functional

Diagram,

Ultrasonic

Tank

3-4 .

........................ System

3-10

....................

Brtdge/Maniuplator

Bridge/Manipulator

...............................

Typical

Paint-Brush

Transducer

Typical

Double

3-10

.................

3-11 3-11

......................

Transducers

3-6

3-9

...........................

C-Scan

and

......................

3-14

.........................

3-15

Straight-Beam and Angle-Beam Transducers .............. Flat and Contour-Corrected Transducers .................

3-15 3-16

Focused-Beam

3-16

Shortening

Contact

Transducer,

Contact

Transducer,

Area/Amplitude

Blocks,

Reference

Functional

Set

Tester,

................

3-18 3-20

...............

3-21

....................

3-22 3-22

Thickness

Thickness

Tester,

Stroboscopic-Type

Thickness

Tester,

Functional Diagram, Manually-Tuned Bond Testers ...................................

Tester

...........

Modulated

Inductance

Modulated

Capacitance Resonance

Testing

Transducer Reference

Operating

Range

Blocks

....................

3-23

......... Modulated

Tester

Light Display .......................... Transducers ............................

9 Mc Resonance Resonance

(Hitt)

Inductance

Oscilloscope-Type

Stroboscopic Resonance

3-17

...........................

Resonance

Thickness

................

.....................

Blocks

Basic

Blocks

Diagram,

Meter-Type

Grounded

Blocks

Reference

Reference

Special

.....................

Grounded

Internally Reference

Distance/Amplitude ASTM

in Metal

Externally

.......

3-24 .... . . .

3-25 3-25 3-26 3-27 3-28 3-29

..............

3-30 3-30

CHAPTER 300 This

EQUIPMENT

GENERAL chapter

covers

manufacturer's

the

facturers' information.

recommendations

PULSE-ECHO

1.

commonly-used

in most

instructions

301

more

manual,

maintenance

All

3:

cases,

for the

ultrasonic

provides

unit

and

supersede

other

this

testing

a review more

of theory,

specific

chapter

equipment.

in the

The

operation,

information.

event

and

Manu-

of conflicting

UNITS

GENERAL makes

functions instrument essential a.

of pulse-echo common

equipment

to another

Power for

according

Supply.

Circuits

units,

The

converts

within

the

fication

the

specimen

test

unit

are

varies

provides

basic

from the

one

following

supply,

pulser,

received

from

of the

line

supply

or,

and

energy

its

holder.

and

reflected

into

electrical

The

introduces vibrations signals

from

for

ampli-

generator

the

of electrical and

is usually needed

test

pulser

energy Return

routed

controls

display with

to provide The

is sometimes

timer

is the by the

from

the

test

unit. a sweep

a visual is the

referred

tube)

(triggered

pulses

to the

an oscilloscope

specimen.

and

(a thyratron

genera-

image

source

to as the

of the

of all rate

genera-

3-1) various

functions

timer,

and

may

Supply.

fuses.

and

from

for

of controls

and

crystal

to the transducer.

display

to the

(Figure

or pulse

amplified,

generator,

receiver,

Power

functions

unit.

receives

them

all basic

is served

of the

it also

bursts

applied

The

marker

provided

which

to ultrasonic

converts

pulser

received,

timing signals tor or clock.

Controls

and

for

in the

consists energy

high-energy

are

are

CONTROLS

of current, supply

specimen;

The

Display/Timer. signals

a.

providing

functions

display.

which

tor,

description

circuitry,

given Each

contained

transducer

into

of short

specimen

power

electrical

Pulser/Receiver. timer)

supply

a battery

test

and

source

2.

electronics of the

manufacturer.

for the

from

Transducer. vibrations

d.

to the

constitute

some

crystal

c.

similar

Nomenclature

s.

instrument,

b.

have

to all makes.

After

vary The

from

power

turning

of the

display. one

instrument

system,

The nomenclature

type

of unit

supply

is usually

on power,

there

as power

in the

following

to another. controlled

are

used

such

certain

by ON-OFF time

delays

switches to protect 3-3

1

23

4

5

6

7

x.J

17 1. SENSITIVITY, VERNIER 2. SENSITIVITY, COARSE 3. OSCILLOSCOPE SCREEN 4. VERTICAL 5. HORIZONTAL 6. INTENSITY 7. SWEEP DELAY, VERNIER 8. SWEEP DELAY, COARSE

9. 10. 11. 12. 13. 14. 15.

Figure circuit b.

elements

specimen

is

one

jack

adjusted

for

through

to permit

R (receive) A TEST of

the

Gain

selectors

or

low

level

noise

of the

adjustments The

for

consist

marked

SCALE are

controls

made, and

transmission

ls

available of

FINE

and

are

ILLUMINATION the their

control usually and

screwdriver functions

given

control is in mega-

sensitivity video

display

screwdriver-adjusted ON-OFF

the

an

provided.

controls for

pro-

only.

for

a clean is

is with

frequencies

COARSE

For

Jack

receiving

frequencies

to

called

provided

of operating

For

connected

a transmitter, for

test

controls. are

a T (transmit) as

the

testing,

transducer

a range

a REJECT controls

TUNING circuits

use

SENSITIVITY.

eliminated, display

the

into

transducer

for

of another

with

PULSE

testing,

NORMAL

usually

control

The

exception

justment.

or

use

transmitted

receive

double

transducer

A selector

controls

Display/Timer.

initial

for

FREQUENCY

one

and and

pitch-and-catch

THRU

R jacks.

cycles.

LENGTH

For

one

Controls

energy

transmit

transducer. or

for

of ultrasonic

the

provided

switch T and marked

the

same

Unit

13 TRANSMIT JACK RECEIVE JACK TEST, THRU/NORMAL REJECT FREQUENCYSELECTOR PULSE TUNING PULSE LENGTH

warm-up.

PULSE

connecting

jack

usually

with

by testing,

the

Pulse-Echo

pulse

transmission

vided

14 16. 17. 18. 19. 20. 21. 22.

instrument

The

transducer

16

Typical

during

Pulser/Receiver.

single

c.

3-1.

15

DRUM DIAL, MATERIAL VELOCITY IN #SEC SWEEP SELECTORS FOCUS MARKER, ON/OFF, COARSE MARKER, VERNIER POWER, ON/OFF, SCALE ILLUM ASTIGMATISM

display

with

POWER. seldom unit

After require

are:

ad-

(1)

Controls

VERT. screen.

Controls

(2) HORIZ. screen.

(3) INTENSITY.

Varies

focus

(5) ASTIG.

Corrects

for

(6) POWER entire Timer

unit

which

provide

to suit

DELAY

control

display

the

on the

Other

Controls.

of SWEEP

and

a back

side Other

at the

power

initial

on for

of grid

rate

of the

the

reflection

of the

turns

DELAY

thickness

by changing

screen.

illumination

adjustments, to position

introduced

that

consist

used

with

right

control

adjusts

fine

screen.

oscilloscope

rotation

material

is also

screen

visible

Dual

oscilloscope

as desired.

oscilloscope

across

oscilloscope

on the

or astigmatism

ILLUM.

and

on the

of display

on the

beam

usually

coarse

display

of display

distortion

Clockwise

controls

generated, the

SCALE

unit.

position

of trace

of electron

and

of the

brightness

Adjusts

time

position

horizontal

(4) FOCUS.

transit

d.

vertical

and

SWEEP

that

pulses

test

pulse

or multiples

lines. controls are

specimen. on the

The

left

of back

side

of

reflections

screen.

controls,

which

are

refinements

not always

provided

are:

(1)

Markers.

The

to serve

the

marker

same

circuit

purpose

provides

as scribe

square marks

waves

on the

on a ruler.

sweep

This

line

circuit

,E

V

is activated

or left

selection.

Usually,

MARKER

may

The higher and the more are

involved

be located

(2) DAC

or STC.

Time

Control),

or TVG

(3)

and

Damping.

pulse

olution

The

adjusts

(4) IF-VIDEO. display,

the

is improved The full-range

like from

duration

length

IF-VIDEO

TCG

IF (intermediate

spacing Since

or

marker

fre-

of square marker cirmarker

train

STC

(Time

to compensate

is shortened

switch

of the

or clock,

discontinuities

values

ON-OFF

CALIBRATION

Correction),

called

used

of the wave

by higher

for

controls

unit.

units

are

the

timer

Amplitude

Gain)

reflected

the

switch

selection

the closer measurements.

control

(Distance other

be a MARKER

to permit

from

timer

Varied

by a MARKER

also

timing

on the

(Time

will control

with

DAC

display

the frequency, accurate the

tude of signals men.

which

Kj

there

ADJUSTMENT

quency. waves, cuits

out of the

deep

by the applied

(Sensitivity

Corrected for

a drop

within

the

DAMPING

Gain), in amplitest

speci-

control

to the transducer.

Res-

of damping. is used

to select

frequency)

the

desired

type

of

or VIDEO.

3-5

(5)

Transducer Voltage. High for the transducer with the

(6) Gated

Alarm.

when

Gated-alarm

discontinuities

specific, Signals

appearing

within

units

Start loscope

gate

location

of automatic

may

within

three

be monitored

controls

START of the

Length

or Width.

trailing

edge

The

A-scan

system

material

under

horizontal

of the

The

control

is used

gate

on the

for

ad-

oscil-

gate

length

LENGTH

of the

gate

or WIDTH or the

control

location

is used

of the

for

gate

edge.

Alarm Level or Sensitivity. The alarm LEVEL or SENSITIVITY control is used for adjustment of the gate vertical threshold to relay.

On some

units,

relay to external

V

base

is a data test line

presentation

on the

screen

on the

method

to display

of an oscilloscope

oscilloscope

C_r

screen

_

as

the

Figure

3-2.

A-Scan

returned

shown

indicates

signals

in Figure

elapsed

time

from

3-2. (from

A

FRONT SURFACE REFLECTION

B C

DISCONTINUITY RESPONSE BACK SURFACE REFLECTION

OSCILLOSCOPE

3-6

on to

EQUIPMENT

the The

specimen.

automatically

of the

a socket is provided for connecting the alarm components. A-SCAN

up

as follows:

or DELAY

leading

setting

are also passed control devices.

turn on signal lights or to activate an alarm

3.

by

the test

These signals and to external

alarms

screen.

adjustment

(c)

The

of the

use

is accomplished

areas

gates

have

the

This

or zoned

these

usually

or Delay.

Justment

(b)

detected.

gated

driving current is selected VOLTAGE switch.

enable

visual or aural alarms. or strip chart recorders

Gated-alarm (a)

units

are

controllable

to operate facsimile

or low voltage TRANSDUCER

left

SCREEN

Presentation

V

to right),

and

velocity terms

in the

vertical

sonic depth

The

spread,

and

are

can the

factors.

Most

amplitude

the

sweep

the

A-scan

units

needed

across

be used

represent

the

the

size

or back

ultrasonic

the

screen,

when

intensities of the

to evaluate

of the

size

re-

soundbeam

of this

the

ultra-

discontinuity,

an oscilloscope

advantage

in

the

to determine

surface,

incorporate Chief

a given

Conversely,

may

front

phosphor.

information

sample.

to determine

from

For

directly,

time

or pips

be used

discontinuity

amplitudes.

be calibrated

indications may

a medium-persistence

it provides

signal into

known,

vertical

to the

other

with

sweep

These

or distance

shows

of penetration

sample

soundbeams.

coated

the

or depth

of the

velocities.

flected

deflection

specimen,

of distance

dimensions

that

the

screen

equipment

is

position

of the

and

discontinuity. 4. The

B-SCAN B-scan

vides

EQUIPMENT equipment,

these a.

in addition

of the

persistence

of the

nism

motion

with

Image-traclng amplitude

The

3-3, of the

X axis. cross-section to evaluate

for

a permanent

A-scan

unit,

pro-

by use

of a Iong-

oscilloscope

the

screen

in synchro-

sample.

or brightening

in proportion

to the

where

cross-section on the

and the

Chief advantage view of the

distribution

oscilloscope

of the sample the

sample

are

B-scan and the

shape As

made

to the

signals

are

of

shown

in

vertical routed

to

equipment is that a longdiscontinuities within it

cross-section

and

and

is of interest.

amplifier/position

scanning, entire

the

image

to photograph

the

is retained oscilloscope

record.

EQUIPMENT is intended

automatic in a plan used

is used

view,

but provides

recorders

and

As the

to provide

scanning

a helix

edge and is connected ultrasonic test unit. drum.

useful

tube,

the

on the along

a sample

In high-speed

equipment

bar

screen

modulation

connections ray

enough

commonly printing

sweep

cathode

long

tinuities

of the

received.

is particularly

displayed.

C-SCAN

spot

intensity

signals

are

screen

oscilloscope

transducer

within

the

the horizontal persistence

speed

spot

discontinuities

Figure

C-scan

components

coating.

of the

system

Y axis

on the

Image-tracing

of the

B-scan

large

image

phosphor

Deflection

c.

5.

basic

functions: Retention

b.

to the

drum

use drum

in ultrasonic no depth

the

record

testing.

to one terminal sliding

paper

in Figure

3-4.

of the output is connected

contact

point

of the

C-scan

or orientation

a chemically-treated as shown

electrically The o_her turns,

a permanent

The

test

when

high-

displays

the

discon-

information. that

is passed

printing

bar

The

most

between has

a

a narrow

terminals of the amplifier in the to the helix mounted on the helix between

the

bar

and

the

helix

I

OSCILLOSCOPE

I SWEEP Y-AXIS

J

TIMER

9

SCREEN_ BEAM

X

I AMP"F'ER _ _

INTEN SITY

-/4-----

POLSER ]

MECHANICAL

(_

LINKAGE

__r.r_'_

TRANSDUCER

X-AXIS

,F

,_,,. , _ION

1 i'_

1

Figure moves

back

and

point

determine

the

drum

produces

one

ment

of the

across amount line

of print-out

across whenever _

B-Scan

paper.

of scan.

so that, BAR

3-3.

the

transducer

oscilloscope PRINTING

forth

_,-_ TE ST SPECIMEN

the

Variations produced

The

paper

test

in electric on the

movement

surface.

a signal

Presentation

The

paper.

amplifier

... FLAWS

HELIX DRUM HELIX

Figure 3-8

3-4.

C-Se_

Presentation

at the

contact

One revolution

is synchronized

(pip) of predetermined

_

current

is also amplitude

with

of the the

connected

moveto the

is displayed,

a change the

of current

occurs

discontinuities

recording of the

is produced

indicates

the

projected

as

seen

ing does

not indicate

the

depth

corders

produce

of the the

a shaded

discontinuity. scan

lines,

as

continuities

are

in Figure

from and

produce

by the

the the

a change

specimen alarm

on the

302

lines

from

control

setting

rails, bridge.

tanks

of immersed

mounted corder

discontinuity

in the

test

and The

(no line) of the

outline recordre-

outline

by the

areas

may be reversed

remainder

the

the

be indicated

the white

C-scan

Some

to indicate

of

The C-scan

specimen.

3-5, may

recorders the

surface.

specimen.

in Figure

where

test

a record

of

absence

represent

so that

specimen

the

dis-

is repre-

on the

recording. the

The

recording

determines

recording.

front

by the the

Figure

and back

surface

instrument

gating

amplitude

of the

3-7

a functional

shows

signals circuits,

signal

(pip) diagram

AND BRIDGE/MANIPULATOR

GENERAL

Ultrasonic ning

the

outline

and

C-scan

eliminated

TANK

of the

manner,

of the marked (or unmarked) area of the recording The same signals that generate the pips on the

are

ULTRASONIC

I.

3-6,

sensitivity

required to produce a change of the C-scan system.

width

shown

of some

the

above

discontinuity

sented by blank space. The extent indicates the size of the recording. A-scan,

as

In this

scans

discontinuity

line,

print-out

represented

and

directly

the

contact.

transducer

of the

scan

shown The

bar

length from

On others,

discontinuities.

printing

as the

specimen,

the

test

in the

over

test a fairly

as shown while Most

and

bridge/manipulators specimens. large

water

in Figure

transversing of these

3-8. power

units

are

are Modern

tank, Drive units

necessary

units

consist

to support power move

automated,

units the

equipment of a bridge

a pulse-echo move

the

manipulator

although

for

some

high-speed

and

manipulator,

testing bridge from

early

unit

along side units

scan-

the

to side are

and

a re-

tank

side

along

manually

RECORDING PAPER FEED MOTION OF TRANSDUCER

DISCONTINUITY

Figure

3-5.

C-Scan

Principle

of Operation

the

Figure 3-6.

X

Typical C-Scan Recording

X

Y

BEAM

DEPTH l_

IRATE I

GATE

POS,T,ON _ _ *

_,_,

_"

GENERATOR

T

"_,_

1

._x-_xl;Po_,_-,o.

l'v

/

t'3 I_TRANSDUCER

l-I

_='_

Figure operated. as

automatic

I TESTING

DEPTH

Functional units,

Diagram,

a C-scan

recorder

C-Scan

System

is also

mounted

on the

bridge

shown.

2. The

On most

3-7.

i

ULTRASONIC ultrasonic

3-10

tank

TANK may

be of any

size

or

shape

to accommodate

the

test

specimen. _'_

Figure The

water

depth

water. for

is usually

Adjustable

support

water

3.

Ultrasonic

sufficient

brackets

of the

test

containing

usually

3-8.

specimen.

a wetting

maintained

and agent.

Tank

for

and

coverage

lazy-susan

of the

turntables

The

water

For

operator

at 70 ° F by automatic

Bridge/Manipulator specimen are

couplant

provided

in the

comfort,

tank

or more

on the

tank

is clean,

the water

of

bottom

deaerated

temperature

is

controls.

BRIDGE/MANIPULATOR

The

bridge/manipulator

test

specimen

Figure

3-9

moved

along

with has the

unit

is primarily

an immersed

a bridge tank

with side

intended

transducer. a carriage

rails.

The

The unit

at each

manipulator

to provide stripped-down end

so the

is mounted --

___CABLE

<

__

_SCANNER.

-'_"---.._:.

_"_r___.__J

Figure x_z

by a foot

3-9.

a means

of scanning

version bridge

shown may

in

be easily

on a traversing SEARCH

the

mecha-

OR

TUBE

MANIPULATOR

Bridge/Manipulator 3-11

nism, enabling movementof the manipulator from side to side. The traversing mechanism is an integral componentof the bridge assembly. The search tube is usually held rigid, as shown, at right angles to the surface of the test specimen. Locking knobs are provided on the manipulator to allow positioning of the search tube in two planes for angle-beam testing. When automated, electric motors are addedto power the bridge carriage, the traversing mechanism, and the up-down movementof the search tube. The pulse-echo unit andthe recording unit are also mountedon the bridge, with all power cords secured overheadto allow movementof the bridge along the full length of the tank. 303

TRANSDUCERS

1.

GENERAL h,

In ultrasonic energy,

testing,

the

information screen. for

instrument

part

sensitivity

Transducer

is the

of the wher'e

and

by two terms:

of a transducer

is its

transducer.

condition

After

of the

it is visually

of a transducer,

described

sensitivity

discontinuity

transducer.

same

transmitting

material

displayed

for that

matter

sensitivity

ability

and on the

the

sound

relays

the

oscilloscope

testing

system,

are

and resolution.

transducers

echoes

amplitude

block.

do not always

Transducer at a specific

to detect

by the

reference Even

manufacturer

scope screen. bottomed hole, 3.

is measured

in a standard

a specific

of its

Precise of the

produce

from response

transucer

same

size,

identical

small

discontinuities.

from

an artificial

sensitivity frequency,

indications

is unique

to

material

by

and on a given

sensitivity is rated by its ability to detect depth, in a standard reference block.

a given

oscillosize

flat-

RESOLUTION

The

resolution

echoes and

the

for

the

from echo pulse,

energy

from

A small 4.

or

resolving

two targets from

transducer

voltage

The

to the

capabilities

system

echoes

SENSITIVITY

The

the

of the

back

most

2.

ear

hears

The

the

the

transducer

close

to stop

"ringing"

is a measure

most

quartz,

lithium

present

are

together

discontinuity

a ringing

MATERIA

of a transducer

a small

of its

transducer

discontinuity,

three

power

just

refers

in depth: just

for

resolving cause

beneath

the

the after

power.

a wide, surface,

ability

example,

beneath

or vibrating,

to its

the

Long

The been

"tails"

high-amplitude, is masked

time

echo required

shocked

by a large

or bursts

of sound

front-surface

by the

the

front-surface

surface. having

to separate

ringing

echo. signal.

LS common

piezoelectric

materials

sulfate,

and

ceramics.

barium

titanate,

polarized lead

metaniobate,

used

in ultrasonic

The and

lead

most

common

zirconate

transducers ceramics titanate.

are at

a.

Quartz. with

In the

the

has

and

300 ° C.

They

are

and

less.

also

least

materials. high

but, Quartz

It is insoluble

Quartz

used

has

in

good

efficient

It also

voltage

interference.

limited

genera-

suffers

to drive

and

have

sulfate energy

They

do not

energy;

other

from

it at low

a tendency

are

are

well

the

on low

usable

up to about

strength,

some

mode

to age. are

and

are

intermediate

and

are

affected

is very

below

hand,

operate

and

low mechanical

sulfate

at temperature

they

transducers

age

Lithium

on the

by moisture,

by relatively

Lithium

to use

transducers,

of ultrasonic

of ultrasonic

sion

X-cut

less

it is the

requires

unaffected

limited

Sulfate.

energy.

planes.

and

exclusively,

stability.

Unfortunately,

ceramic

practically

sonic

crystals,

of the commonly

interference,

Lithium

Natural

energy

generators

are

CRYSTAL

used

and thermal

aging.

polarized

efficient

voltage,

receivers

5.

almost

and wear-resistant.

interference

The

conversion c.

used

it is being

electrical, hard

were

s.

Ceramic. most

materials

resists

conversion

frequencie b.

of new

and is very

of acoustic

mode

transducers

chemical,

liquids

uniformity tor

quartz

development

excellent

most

past,

the

most

efficient

as a generator very

little

fragile,

of ultra-

by mode

soluble

conver-

in water,

and

165 ° F.

PLANES such

as quartz,

crystals

are

used

cut

in transducers

perpendicular

are

to the

cut

X-axis

in either

and

one

produce

of two

longitudinal

V

sound shear

waves. sound

6.

The waves.

Y-cut

TRANSDUCER

Transducers

are

to 6-inch

wide

perience

and

contributing straighter beams

made

part,

are

generally

ducers

are a.

in a limitless

requirement

factor

to its

for

small

used

limited

provide

to gain

instance,

spread)

for

transducers

Y axis

and

Transducers.

The

pattern

is necessary a long,

varies to maintain

narrow

wide

crystals, very

little uniform

produce

rectangular

very

carefully the

sensitivity. beam

extremely

result the

The for

the

transducers

are

so that

the

of the

Paint-brush

(in cross-section)

very

into

high-frequency

length

the

detecting

energy

transducers entire

is a

narrower

single-crystal

matched

ex-

transducer,

sound thin

small

of much

of a transducer

ability

large

paint-brush over

larger

more

the

from the

Size

greater The

because

and chipping.

of smaller

are

frequency.

transmit

penetration.

frequencies

shapes

the

a given have

transducers

deeper

and shapes

applications.

to breaMng

pattern

beam

many

special For

beam

larger

to lower

Paint-Brush

This

to the

of sizes

The

many

high-frequency

susceptible

of the

(less The

a mosaic

perpendicular

number

performance.

soundbeam

so are

cut

transducers.

the

discontinuities.

test

are

TYPES

paint-brush

the of the

small

crystals

trans-

made

up of

intensity transducer.

transducers for

scanning 3-13

!

U--__X large

surfaces,

test the

specimen. size,

and their

purpose

Smaller,

more

shape,

Figure

3-10

orientation,

shows

is to quickly sensitive

and

a typical

discover

discontinuities

transducers

exact

location

paint-brush

are

of the

then

in the

used

to define

discontinuities.

transducer.

COAXIAL

Illii

Ili l llllllllill

r

A

CRYSTAL

BEAM

Figure b,

Double

in that,

receiver two

single

They

stacked

separated

types

straight-beam the

test

tinuities

direct

waves

angle-beam ducer

test

energy

and the surface

double

for

by side

cross

are

single

trans-

only, unit

a

is in essence

pitch-and-catch

for

and the

straight-beam

In all cases,

other test-

the

crystals

interference.

Figure

3-11

classified

as either

are

surface at the

desired

surface

used

test

"straight-

surface.

specimen

Angle-beam

surface

used

into

at an angle

to locate

discon-

and

to determine

the

90 and

180 degrees

to the

shear,

conversion.

usually specimen,

angle.

test are

term

is transmitted

to propagate

by mode

a wedge, of the

test

between

also

specimen use

the

transducers to the

The

the transducer to the

into

angles

also

transducers.

from

at an angle

test

the

transmitter

testing.

to block

Angle-beam

at right

the

holder

side

angle-beam

soundbeam

transducers

face

into the

3-14

the

the

is the

(perpendicular)

transducers into

same

or angle-beam sound

oriented

Angled

in the

from

be a transmitter

transducers.

normal

oriented

face.

receiver,

Transducers

90 degrees.

discontinuities plate

the

specimen,

than

and

barrier

of double

that

differs may

be mounted for

transducers

transducers other

may

Transducers.

means

transducer

one transducer

or paired by a sound

Angle-Beam beam"

unit,

LENGTH

Transducer

transducer

mounted

double

receiver.

both

double

single

transducers

and

shows

the

Paint-Brush

or both transmitter

In the

is the ing,

Typical The

while

only,

testing.

are

3-10.

Transducers.

ducer

C.

("

of plastic, to direct

In immersion

slze

surface,

and

In contact between the testing,

of

sur-

testing, the

sound

transenergy

angulation

P

ANGLE-BEAM (PAIRED)

STRAIGHT-BEAM

(STACKED)

Figure of the

soundbeam

transducer Both do

and

Unit

the

transducer

are

often

harmful

or

to the

the

Focused

effects

of foreign

Frontal

contour-correction surface

indication

are

lenses.

part

frontal

These

surfaces cylindrical

out the

at the

desired

members wear, and

sound

are

to protect are

or the

the

front

perpendicular known

sharpen

distance

to

plates

breakage,

radii

lenses

sound-travel

added

wear

energy

and

angle.

3-12.

transducers,

from the

of a straight-beam

in Figure

or liquids,

to direct

on curved

by evening

test

shown

crystal

substances

points

angle

On contact

fragile

shaped

the

Other

reasons. the

units

at all

Into the

Transducers.

to protect

Transducers

by varying

transducers

various

added

surface

Double

soundbeam

angled

for

electrode.

Typical

is accomplished

to direct

straight

Faced

3-11.

as

the

front-

between

the

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CRYSTAL

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PLASTIC

WEDGE

ANGLE-BEAM TRANSDUCER (CONTACT)

STRAIGHT-BEAM TRANSDUCER (IMMERSION)

Figure

_

and

Angle-Beam

Transducers 3-15

transducer ducers

and

the

is shown

test

surface.

in Figure

A comparison

3-13.

Other

of flat

acoustic

and

lenses

contoured

focus

the

soundbeam

FLAT

CONTOURED TRANSDUCER

TRANSDUCER

Figure from

the

3-13.

creased

the intensity,

maximum beam

specimen

surface. also

The the

closer

as light

the

the

increased

to the

test

narrow,

the

very

shortens the

increased the

beam its

point

case,

beam

enters

sensitivity;

to the transducer near-surface

_

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Figure

3-14.

Focused-Beam

LENS

GREATER

Shortening

CONVERGENCE

NEW POINT OF FOCUS IN METAL FOCAL DI STANCE IF IN WATER

in Metal

range. the

the test

also, (which

resolution.

.....

SOUND BEAM

of

because

WA'r E_ L ,.-'/

of in-

discontinuities its usable

in this

when

closer

improves

small moves

lens,

3-14,

transducers

blunt-pointed

but

produces

intensity

Focused

soundbeam

of a second

intensity surface)

focused.

of detecting

In Figure

of maximum

are

transducer,

effect

as shown

point

a long,

Focusing

towards has

into

Transducers

beams

ts capable

area.

ts refracted,

moving

Contour-Corrected

energy

which small

intensity

test

and

much

sound

in a relatively The

Flat

transducer,

concentrate

3-16

trans-

is The

V

disturbing

LJ

effects

concentrating because

surfaces

energy

area

indications

of other

will

Transducers.

angle-beam of two ways. contacts

test

3-15

surface

to the

thickness

inches.

transducers

are

the

made

in which is made

one face

true

dis-

combined

both are

through

by simply

the

range

for

transducers

type

ground

reduced

is true,

compared

0. 010 to 2.0

the

also

This

area,

useful

contact

are

In a smaller

large The

shows and

noise beam.

at.

be relatively

Straight-beam

Figure

the

looked

Contact

testing.

metal

a smaller

indications.

is approximately

Contact

and

into

is being

irrelevant

transducers e°

sound

a smaller

continuity noise

of rough

the

of focused

straight-

and

grounded

in one

of the

crystal

test

surface.

the

CASE COAXIAL

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...... Figure These

3-15.

transducers

reasonably 3-16,

smooth

coaxial

FREQUENCY

The

frequency

tics

are

higher higher The

by the

frequency,

the

sensitivity.

frequencies

the

on electrically-conductive

and the

the

face

unit

of the

is faced,

crystal

immersion-type

are

as

shown

provides

for

transducers

immersion-type

transducers

completely

materials

water-proofed,

with

in Figure an internal

are

internally

including since

the in use

they

SELECTION

the higher

front

Grounded

submerged.

of a transducer

affected

Externally

When

on the

connection,

completely

only

surfaces.

In addition, cable

Transducer,

used

All angle-beam

grounded.

7.

are

an electrode

ground.

are

Contact

need the

frequency,

between

is a determining

0.2

for

shorter

sensitivity. the

frequency

the

the

and

25 Mc,

in its

Sensitivity

wavelength;

Transducer thinner

factor the and

crystal.

but contact

is related shorter

crystal Most

testing

use. the

thickness ultrasonic is generally

Basic

characteris-

to wavelength: wavelength, are

also

testing limited

the the

related. is done

at

to 10 Mc

3-17

COAXIAL

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CONNECTOR

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Ii;iiii!ii:i ;i _"

Figure because

crystals

contact

ground

testing.

the

the

and

3O4

10 Mc are

Grounded

too thin

the

and the

frequency

and

fragile

for

practical

are:

the greater

attenuation;

Internally

of a transducer,

greatest

the

RYSTAL

the

sensitivity

penetration

greater

and

(least

beam

resolution,

spread)

but the

atten-

is poor.

of a transducer,

but the

straighter

the

deeper

the beam

the

spread,

penetration

the

less

and

the

the

sensitivity

resolution.

At any

given

beam,

but the

frequency, less

the

the

larger

the transducer,

the

straighter

the

sound-

sensitivity.

COUPLANTS

1.

GENERAL

The

couplant,

specimen. sure

as the A couplant

efficient

complishes all

above

frequency and

is also lower

less

c.

the

soundbeam

The

b.

use

Transducer,

considerations

higher

uation

Contact

for

Other

The

a.

3-16.

WEAR P_T:

air

between

variety

implies,

is used

couples

between

transmission

by smoothing the

of liquids,

following

3-18

sound this

name

transducer semi-liquids,

from out the and

the

the

the

transducer

transducer

transducer irregularities test

pastes,

surface.

and

even

face to test of the The some

to the

surface

and the

test

surface. test

couplant solids,

surface

The

surface

test to en-

couplant

and

can that

of the

ac-

by excluding

be any of a vast

will

satisfy

the

requirements:

a.

A couplant transducer

wets both the and excludes

b.

A couplant

is easy

surface all air

to apply.

of the between

test specimen them.

and the

face

of the

c.

A couplant is homogeneous case of a nonsolid.

d.

A eouplant

is harmless

e.

A couplant

has

a tendency

f.

A couplant

has

an acoustic

the 2.

test

IMMERSION

In immersion agent,

usually

maintained

3.

faces For

305

rough

clean,

For

by automatic

in the

that

that

but

is easy

of the

of the

to remove.

transducer

test

face

and

surface.

deaerated

operator

tap

water,

comfort,

the

with

water

an added

temperature

is

controls.

of couplant

used

depends

One-part

on relatively light

oil and grease the

primarily

(such

are

used

on the condition

glycerine

smooth

oils

couplant

REFERENCE

testing,

The

with

surfaces,

two-parts

of the

water,

oil)

with

and

on hot

as possible,

with

surfaces

is as thin

sur-

and

and is an excellent

as SAE 20 motor on rough

selected

a

couplant.

a wetting

agent,

or vertical effective,

BLOCKS

blocks

specified blocks,

things:

all discontinuity

reference

standard

for

are

to evaluate

the

a given

used

specified, specimen

or

test.

that

the will

is accomplished

block

of the

material.

size,

bottomed

holes.

present

reference

blocks

Standard

treat.

Test is the are

to meet

blocks

are was

Alcoa

made added

series

reference the

part.

the

blocks,

test

at the

blocks

are

predetermined are with

from same made

from

standards

painstaking

area/amplitude

with

care

blocks;

the

the

indication reference

carefully

selected, attenuation,

most the

drilled

the

only

familiar Alcoa

size

test

of sound so that

three

of the

in a,standard

by carefully

The

and

two as re-

within

them

called

does

discontinuities

depth

of

equipment

is performing all

represented

intentionally.

often

ultrasonic

of discontinuities

indications

size,

stan-

or sets

Standardizing

at which

Evaluation

A,

blocks

combination

Discontinuities

one that the

test

setting

of known

stock

and heat

the

to a reference

reference

to standardize

or gain

by comparing

discontinuity

compared

standard

from

be detected.

an artificial same

are of many

instrument/transducer

from

ultrasonically-inspected

one

testing

indication

a sensitivity

larger,

be any Ultrasonic

in ultrasonic

it establishes

indications

may

discontinuity

it verifies

quired;

t

particles

GENERAL

dard.

-nuity

surface,

between

approaching

than

transducer.

In all cases, results.

In ultrasonic

grain

or solid

and transducer.

on the test

impedance

a couplant.

surfaces,

Heavier

STANDARD

1.

specimen

to stay

more

choice

is often

slightly

surfaces. consistent

test

the by the

agent,

bubbles,

COUPLANT

testing,

used.

for

at 70°F

contacted

wetting

of air

test

preferably

nothing

is used

CONTACT

In contact

to the

free

COUPLANT

testing,

wetting

are

specimen,

and

flatdiscontisets

series

of B or

3-19

Hltt, distance/amplitude blocks; andthe ASTM basic set of blocks that combine area/ and distance/amplitude blocks in one set. 2.

AREA/AMPLITUDE

The

Alcoa

square. each the

series

block.

FBH

A set

A 3/4-inch

No.

hole as

that

is,

screen

they

increases

a No.

provide that

the

reference

1/64-inch

in the

has

(height)

to the

made

in size from

and

1 15/16-inches

in the bottom

1 block

center

through

the block

of

8/64-inch

numbers

diameter

the

of the

increase

are

No.

a 3/64-inch

of checking

amplitude

long

is drilled

As implied,

3 block

blocks

3 3/4-inches

(FBH)

3-17.

a means

in proportion

area/amplltude

blocks, hole

are

in Figure

e.g.,

confirm

of eight

diameters

blocks

SET

flat-bottomed

shown

diameter,

Area/amplitude

consists

deep

The

8 block,

hole

BLOCKS

to the

flat-bottomed

hole.

linearity

of the

test

indication

on the

oscilloscope

of the

2-inch

in

refer

system;

discontinuity.

diameter

Similar

round

stock.

TEST SURFACE NO. 5

NO. 6

NO. 7

NO. 13

r-1

F-1

[--I

Fl

II II

Ii I I II I I ___LA_ _1_1_

5/64

6/64

I I ii I I

7/64

8/64

ENLARGED VIEW OF HOLES (NO. I THROUGH NO. 4 HOLES NOT SHOWN)

Figure 3. The

DISTANCE/AMPLITUDE Alcoa

blocks,

series

all

center

with

at one

3/64,

material. or gain screen with 3-20

and

of the all

indications

test

blocks

also

vary

diameter

as the serve

system

consists

shown size

holes

to the holes.

of the

and 3-18.

discontinuities

of a given

of smaller

discontinuities

distances

1-1/4

setting

inch

and

that

readable over, are

or

cylindrical

are

are: through

depths

indications but will

with

1/16-inch,

1/8-

5-3/4-inch

in

within

serve

as

the test

the on the

not flood

in the

of 1/16-inch available

blocks

standardizing

of no interest.

drilled

distances Sets

Distance/amplitude

display size

metal

at varying

for

diameter diameter,

hole.

metal

of discontinuities it will

same

to provide

increments, in Figure

2-inch

flat-bottom The

as a reference so that

Blocks

of nineteen

in length

surface

in eightg-tnch

to evaluate

set

Reference

SET

flat-bottomed

test

8/64-inch

1-inch

They for

deep the

increments,

a reference

blocks

These

from

through

half-inch

B or Hitt

end.

5/64,

BLOCKS

3/4-inch

to 5-3/4-inches inch

Area/Amplitude

3-17.

the

sensitivity oscilloscope screen

On instruments

so

t

---- 2 1/8 DIMENSION 1/4 A

A

318 112

!

5/8 1/16 3/4

i

7/7 3/4

1 1/4

i

I

e

2 3 3 4 4 5 5

DIMENSION B 3/64 5/64 8164

C

Figure

equipped, tance

these

blocks

amplitude

cation the

4.

ASTM

same

basic holes

FBH

a metal

and next

seven 1-1/2,

ing

blocks

have

basic the

FBH Figure

similar

or

cold

material. In sound

set

so that on

consists

the

STC

(sensitivity

a discontinuity

the

time

of a given

oscilloscope

and

8/64-inch the

5) and

3-19

working If test attenuation,

center

screen,

have

6

(Hitt)

control)

size

or

will

regardless

from

diameter No.

3,

5,

varying

metal

a basic of the

DAC

produce

of its

and

from blocks

distances,

set.

It is

specimen.

forging,

rolling,

of identical velocity,

and

and

metal

etc., material

the that

are

the

blocks

(dis-

an

indi-

distance

from

affect not

deep,

distances

3:inch with

The inches

test

block treatment,

the

1/4,

two and

metal the

heat

remain6

inches.

distance,

5/64-Inch

prodiameter

relationship. material

acoustical

available,

hole.

of 1/8,

FBH. of 3

flat-

diameter

flat-bottom

distance/amplitude

the

content, all

a 3/4-inch

to the

to the

with

provide

Alloy

has

distances

seven

important

3/4-inch

metal

surface

8 blocks the

block

have

surface

FBH

and

test

test

test

and

also

One

the

the

FBH

that

end.

from

a 5/64-inch

inches

three

blocks

at one

relationship,

shows to that

2-inch

of 3 inches

each

3,

set,

of ten

in the

distar_ce

area/amplitude

(No.

or

set

blocks

3/4,

vide

to

Blocks

SET

drilled

1/2,

In this

used

amplitude

BLOCKS

bottomed The

are

Reference

3/4 i/4 3/4 1/4 3/4 1/4 3/4

surface.

BASIC

The

Distance/Amplitude

correction)

of the

front

3-18•

3/4

they

be degree

properties must

be

the

same,

of hot of the similar

impedance. 3-21

FLAT-BOTTOM HOLE (FBH) DIA ....

E(SEE

.....

TABLE)

TARGET--.--_.____

I

I METAL DISTANCE

I --,,,--

(SEE TABLE)

METAL

DISTANCE,

FBH DIA IN 64THS

The field

SPECIAL

1/8

1/4

1/2

3/4

1-1/2

3

3

3

6

6

INCH

5

5

5

5

5

3

5

8

5

8

3-19.

ASTM

Refereace

Blocks,

Basic

Set

BLOCKS

IIW (International calibration

in common

INCH

INCHES

Figure 5.

3/4

Institute

block,

use.

/

For .06 /

shown

of Welding) in Figure

irregularly-shaped

reference 3-20,

are

articles,

HOLE

block, examples

40"

reference

necessary

angle

beam

standards

to make

one

of the

C

'

50"

miniature

it is often

_SURFACE

""'

and the of other

'L

60"

V

2 DIA HOLE

_.09

I "_

I

SURFACE D

POINT SURFACE A L-I_

I lea .

i II

_ J

II I_T,1

._._L._, I, "PLASTIC

I

II

II II II Ii

I I I I

I INSERT

"_''"_

SU RFACE B

ii ¸ iiii

__UlllATURE

F_re 3-22

3-20.

Special

ANGLE BEAM

Reference

Blocks

i

test

articles

into

fiat-bottom tinuities

are

In other

cases,

structive standard.

so that

and then investigation.

standard

by adding

notches,

etc.

they

Several

individual The

the

of the

discontinuities

cases,

these

by subsequent is developed

detection

results

machining

by careful

of discontinuities,

study

then

in the

artificial

of the

study

in the

become

the

basis

form

of

disconarticle.

of an article

article, for

by de-

the

testing

EQUIPMENT

types

of ultrasonic differ

modulation.

testing in the

Figure

an oscilloscope

3-21

display.

frequency

by changing

motor-driven

capacitor.

a limited

thickness

frequencies

and the

use

available

commercially.

and

method

a functional

oscillator the

control

frequencies such

in the

diagram

circuit

or by a motor-driven

At high range,

are

of presentation

shows

The

inductor

is adjusted

equipment

type

electrically-variable

lower

be removed technique

verifying

TESTING

instruments

quency

over

will

artificial

In some

GENERAL

these with

cuts,

a special

RESONANCE

I.

saw

placed

ultrasonically,

306

a reference

holes,

is modulated

Mc,

variable high

as 0. 005 to 0. 035 inch.

of scales

calibrated

for

multiple

by an

tuning

range

inductor

accuracy

Wide

of

or the

is obtained

tuning

harmonic

INDICATION S _.

of fre-

instrument

either The

on the

of 15-30

width

of a typical

capacitor.

current

Primarily, and

ranges lines

at are

?CALES

SWEEP CIRCUIT COAXIAL

VARIABLE OSCILLATOR CABLE,__

$_EP

AMPLIFIER _.

TRANSDUCER

STEEL

MIO

ALUMml,m

THICKIILr!;S

OSCILLOSCOPE

M

THOUSJ_MDTH$

OF" All

IliCH

,._

SCREEN

4; I_Xji I _C_ t,STANDING , ki! _ll

; IJ

V

WAVES

I

TEST

Figure

SPECIMEN

3-21.

Functional

Diagram,

Resonance

Thickness

Tester 3-23

used for coverage of a wide thickness range. Typical wide-scale ranges are 0. 080to 0.640 inch at 0.75 to 1.5 Mc and 0.065 to 0.510 inch at 1 to 2 Mc. 2.

INDUCTANCE-MODULATEDINSTRUMENT (Figure

Inductance-modulated tor

circuit.

instruments

The

control

tuning

range.

tance;

therefore,

eating

measurements

when

scales,

made length

from

the

tend

the

working

3.

3-22.

For

capacitor

Meter-Type

whose

zontal

sweep

change

of the

of the

Thickness

axis

of the

range

resonant frequency

instrument,

as

outer

edge.

rotation

across

the

shown As the

Tester,

screen.

these

Thick-

Coaxial

ranging

oscillator

from

3

is removed

components

Inductance

to ex-

Modulated

trace

rotates

has with

circuit

through

line

Each

cycle

disc

The

with the

the

hori-

change.

If this giving

The

frequency a series

stroboscopic-type

a neon

neon

or wipers.

of capacitance

vertically,

screen.

a motor-

with

range.

is deflected

capacitor,

brushes

frequency

a frequency

a rotating

contains

is synchronized

screen.

oscilloscope the

which

a corresponding

indicates

on the 3-24,

the

circuit

capacit)r

produces

the

in Figure

into

oscilloscope

tube

indications disc

of indi-

harmonic

limited,

between

capaci-

capable

of 0. 004 inch.

oscilloscope

an oscillator

of the

capacitor

cathode-ray

frequencies,

of harmonic

have

is connected

the

motor-driven

horizontal has

trace

are

thickness

If the

the

low oscillator they

is usually

inserted

to change

of interchangeable

the

oscilla-

INSTRUMENT

rotor

display,

are

in the

transducer.

instruments

oscilloscope

over

transducer

cables

of the

by use

at low frequencies.

CAPACITANCE-MODULATED

driven

3-24

to the

extension

Capacitance-modulated

the

placed

to 25 feet

distance

Figure

plastic,

oscillator

frequencies

instrument,

the

directly

inductor

relatively

attained,

at a minimum

be read

3-23)

is adjusted

have

30 Mc are

and

variable

inductor

instruments near

and aluminum

may

of transparent from

at high

an electrically

on the variable

frequencies of steel

up to 3 inches,

feet

current

Inductance-modulated

nesses, cable

have

3-22

lamp

lamp flashes

mounted

on

in phase

V

Figure with

the

upper because

scanned

quadrant

Figure

Oscilloscope-Type

frequency of the

of the

(center knob The thickness

x._j

3-23.

dial,

stroboscopic

of each these effect.

Thickness rotation.

flashes The

Viewed

form operator

Stroboscopic-Type

Thickness

Inductance

through

a pattern

shown) until division lines most nearly indicator then points to the thickness,

3-24.

Tester,

then

the

readout

of apparently rotates

Modulated

the

slot

in the

stationary harmonic

lights scale

disc

coincide with the light pattern. in inches, on the thickness scale.

Tester,

Capacitance

Modulated 3-25

4.

MANUALLY-TUNED

INSTRUMENTS

Manually-tuned

instruments

than

units.

the

larger

system wide

that

is manually

frequency

manually audible

If this tone

indicated

range

is made

in thick

quency

plates:

of 0. 0145

resonance signal

wide for

Mc.

signals.

example,

If the

to 2.0 from

width sweeps

will steel

is 0.1 per

Mc,

in thickness

indication,

in the

of the

pitch

a resonance

either

narrow

of instrument of the

base

the

specimen,

an

resonance

is

conversion on a con-

detect

discontinu-

laminar

with

each

a fundamental

sweep

produces

produces

seven 700-cps

due to a laminar audible

fre-

an audible

discontinuity

sound.

CRYSTAL

TUNABLE R-F OSCILLATOR

lq

is

percent test

or

or is computed plate

second

complicated

for

Frequency/thickness

instrument

thick

less

Simultaneously,

instrument

an 8-inch

decrease

INDICATOR LOADING

to the the

at 100

A decrease

a proportionate

meter.

are with

type

as 0.5

frequency

modulating

Modulating

in a headset.

produces

attached

that

diagram

available

or a headset.

of a panel

rule

are

such

a resonant

modulation,

units

functional

narrow-modulating

range,

in a loudspeaker slide

Using

portable

a typical

instruments

The

narrow

deflection

on a circular table.

These

produces

is produced

small,

shows

ranges.

a very

by increased

version ities

over

usually

3-25

tuned.

modulating

tuned

frequency.

are

Figure

V __COUPLANT

I

I I I

HEADSET

MANUAL TUNING

Figure 5.

bond

of bond

tester

or delamination

played the

transducer

3-26

Manually-Tuned

are

of frequency

thus

shown

is acoustically its

resistance

instrument

structures.

of constant

is proportional

as a function

vibration

vibration,

in bonded current

transducer

tal

Diagram,

is an ultrasonic-impedance

varlable-frequency of the

Functional

Resonance

Tester

TESTER

BOND

The

3-25.

The

system

used

unit

transducer

for

checking

is driven

lack

by a

amplitude.

The

voltage

developed

at the

to the

amplitude

of the

crystal

vibration

and

on the

oscilloscope

as a distinctive coupled

to vibration,

pattern

to a bonded and therefore

screen. on the panel,

Characteristics oscilloscope

information

its physical

screen. regarding

characteristics,

face

is disof crysWhen panel are

V

shown

on the

patterns

oscilloscope.

are

shown

Figure

on the

face

3-26

of each

shows

two types

oscilloscope

@

©

of bond

testers.

Typical

test

screen.

0

0

FOCUS

INTENSITY

TUNING

3

7

i

21 SWEEP50_160 :

@

I

SENSITIVITY3_60i 21

I

BAND HORIZONTAL

VERTICAL

FREQ SHIFT

2JL

3

FOCUS

INTENSITY

POWER

CAL

_

OUTPUT

ON

OFF

r_

Figure 6.

RESONANCE

INSTRUMENT

Resonance

instrument

responses

may

phones,

indicate

cording,

are a.

Audible

resonant

discussed

vertical

transducer. scale b.

displays instrument

v

These

over

Stroboscopic

lator

following

the

face

Indication. thickness contains

arrangement

type

readings

from

or audible.

Visual

by stroboscopic

a loudspeaker

of indication

resonance

on large-screen

which

indications of the

visual

on a meter,

heard

Oscilloscope long,

types;

lights,

or a pair

including

or

of head-

automatic

re-

paragraphs.

peaks

17 to 21 inches

lights,

notes, Each

Indication.

as bright-line base

of two basic

responses. in the

Oscilloscope

are

by warning

screen.

Testers

INDICATIONS

indications

be displayed

on an oscilloscope

Bond

3-26.

cover are

cathode One type with

by placing

presented

tubes,

frequency

of battery-powered a stroboscopic with

ray

are

with range

a time of the

a transparent

tube.

a capacitance-modulated, in conjunction

cathode

the operating

interpreted ray

indications

portable

light

motor-driven, a modified

slide

instrument

presentation. rule

The sweep

of the

oscil-

harmonic

3-27

matching type. A small neon lamp, shownin Figure 3-27, is made to flash at the instant the sweep capacitor sweeps the oscillator through the fundamental frequency or any harmonic frequency. This neon lamp is fastened to a disc that rotates with the sweepcapacitor, and is viewed through an arcshapedwindow under a circular slide rule. The stroboscopic effect of the rotating disc results in a steady light pattern related to the thickness of the test specimen. The slide rule is then rotated until the m_rks on its harmonic scale match up with the light pattern. The thickness of the test specimen is then read on the thickness scale.

/NEON

BULB

/,_CASE

THICKNESS

SCALE

• HARMONIC

ROTATING

°'sc

,.-"

Figure C.

from

or headphones. the

test

headset. holding tinuities

Light

Display

within

pre-set

specimen usually limits are marked

or absence corder, material cuits

lights

The

a "normal" of this

gate

condition gated

are

The

signal

so that

is included a relay,

used,

as they

do not

Interfere

with

which

or discon-

of the range

hand

indications,

resonance of the

test

of the gate. Gating by small, vertical

a strong

within

of the

to detect

thickness

and location oscilloscope

marking device, automatic sorter, Into a number of groups according are

recording

or a

instrument;

variations

instruments

is adjusted

on the

on a finger

thickness

allowable

trips

worn

automatic

frequency

in a loudspeaker

mounted

lamp,

to oscilloscope

limits.

a resonant

is produced

up when

For

For field work, other with meters, warning

produces

lights

determines the width on the screen of the

or markers.

indicating

that

added

tone

to a ring

Indication.

are

instrument

warning

is connected

Recording

circuits

the

an audible units,

the transducer, are encountered.

signals

lines

When

some

a wire

Automatic gating

3-28

Stroboscopic

specimen,

With

in others,

d,

3-27.

Headphone, Meter or Warning Light Indication. battery-powered units are equipped for indication lights,

SCALE

the

resonant

gated

in turn

limits.

A loss

operates

a re-

or alarm system. To sort to thickness, multiple gating each

other.

edge

signal

cir-

7.

TRANSDUCERS

Transducers used

with

The

example, range

is used

with

range.

Figure

specimen shown wedges

shows

TESTING testing

before

the

frequency is most

require

the

test. the

are

carefully

ground

of taper.

in a 3-28. For

a 4 to 8 Mc tuning

of the of the

transducer

is

oscillator

of a 9 Mc transducer

The

tuning

in relation

at its natural

of reference equipment

The

frequency.

standards and

Standard

to predetermined On these

blocks,

_

CONCAVE SPRING

_

Resonance

for

is standardized

thickness

selected.

SWIVEL

3-28.

generally

selected.

reference

of the

thickness

retest

blocks,

thicknesses the

adjusting to the

material

_

STRAIGHT RIGID

are

available

in Figure

with

frequency

FINGERTIP

Figure

shown

frequency sensitive

use

test.

block

degree

are

BLOCKS

reference

fine

resonant

operating

titanate

oscillator

an oscillator

transducer

of each

as to the

maximum

to the

3-30,

a very

applications,

The

than

barium

of transducers

is matched example,

with

and

types

test

For

units

proceeding

is related in Figure

specific

REFERENCE

at the beginning

block

with

the the

ceramic,

Many

transducer

higher

shown,

resonance

instrument

for

of the selected.

3-29

RESONANCE

ference

of quartz,

a 9 Mc transducer.

As

Ultrasonic

TESTING

testing.

sizes

10 to 20 percent

to sensitivity. 8.

and

frequency

an oscillator

normally

made

resonance

of shapes resonant

RESONANCE

crystals

for ultrasonic

variety

the

FOR

in steps at each

or test

PENCIL

RIGID

_

RIGHT

ANGLE

FLAT SPRING

Transducers 3-29

0.5

1.0

2.0 FREQUENCY

Figure point

is clearly

micrometers,

3-29.

9 Mc Resonance

indicated. the test

When

the

specimen

3.0

Transducer test

is used

specimen for

3-30

3-30.

Resonance

6.0

Operating

8.0

Frequency

can be measured

standardizing

STEPPED REFERENCE BLOCK Figure

4.0

10

IN MEGACYCLES

the

Range with

calipers

instrument.

TAPERED REFERENCE BLOCK Testing

Reference

Blocks

or

CHAPTER

4:

TABLE

OF

TECHNIQUES CONTENTS

Page

Paragraph 40O

GENERAL

401

IMMERSION

TECHNIQUES

1.

General

.....................................

2.

Immersed

3. 4.

Bubbler Techniques Wheel-Transducer

402

4-5 ...........................

Techniques

4-5 4-5

...........................

4-5

............................. Techniques .....................

4-7 4-7 4-7

CONTAC T TECHNIQUE S ............................ 1. General ..................................... 2.

Straight-Beam

3. Angle-Beam 4. Surface-Wave PREPARATION

403

1.

General

2. 3.

Frequency Transducer

Techniques Techniques Techniques FOR TESTING

_

Selection Selection

1.

General

2. 3.

Typical Immersion Standardizing the

4.

Typical

406

1.

General

2. 3.

Typical Typical

RESONANCE 1. General 2.

Typical

3. Typical REFERENCE

407 Figure

4-1

Bubbler

Figure

4-2

Water-Path

Figure

4-3

Stationary

4-8

......................... ......................... ........................

4-10 4-11 4-11 4-11

............................ ...........................

4-12 4-12

............................ .............................

4-13 4-13

....................................

Contact

5. Angle-Beam INTERPRETATION

405

4-7

........................

....................................

4. Reference Standards TESTING PROCEDURE

404 r_

......................................

Testing Immersion Testing

4-13 Procedure Testing

Procedure

................. System ............

4-13 4-17

..................

4-19

Contact Testing Procedure ............... OF TEST RESULTS .................. ....................................

Immersion Test Indications Contact Test Indications

.................. ....................

TECHNIQUE ........................... .................................... Resonance

Testing

Resonance TABLES

Test Results .............................

Procedure

and Wheel-Transducer Distance and

Moving

Adjustment Wheel

4-29 4-34 4-41 4-41

.................

....................

Techniques

1-42 4-43 4-46

. ............

.................... Transducers

4-23 4-28 4-28

4-6 4-6

..............

4-7

TABLE OF CONTENTS

{CONT)

Paragraph Figure 4-4 Figure 4-5 Figure 4-6 Figure 4-7 Figure 4-8 Figure 4-9 Figure 4-10 Figure 4-11 Figure 4-12 Figure 4-13 Figure 4-14 Figure 4-15 Figure 4-16 Figure 4-17 Figure 4-18 Figure 4-19 Figure 4-20 Figure 4-21 Figure 4-22 Figure 4-23 Figure 4-24 Figure 4-25 Figure 4-26 Figure 4-27 Figure 4-28 Figure 4-29 Figure 4-30 Figure 4-31 Figure 4-32 Figure 4-33 Figure 4-34 Figure 4-35 Figure 4-36 Figure 4-37 Figure 4-38 Figure 4-39 Figure 4-40 Figure 4-41

Page Wheel

Transducer

Angular

Single-Transducer Double-Transducer

Through-Transmission Shear-Wave Technique Surface-Wave Typical Transducer

4-8 4-9 4-9

..................

4-10 4-10

.........................

System

Adjustment,

Delay

............... .................. .................

Techniques ..........................

Technique

Immersion

Sweep

Capabilities

Echo Technique Echo Technique

Normal

Adjustment

4- 11

....................... to Test

4-14 Surface

.........

4-15

.........................

4-16

Sweep Adjustment ............................. Standardizing Indications .........................

4-17 4-18

Typical

Contact

System

4-19

Contact

Testing

Reference

Reject Control Back-Reflection Marker

......................... Plate

....................

4-20

Effects .......................... Multiples ........................

Adjustment

4-21 4-21

............................

4-22

Sweep Delay Effect ............................ Test Hole Size Comparison ....................... IIW Test IIW

Block,

Test

Basic

Block,

Sweep

Lucite

IIW Test

Block,

Indications

I1W Test

Block,

Checking

Weld

Test

Scanning

Length

Wedge

Adjustment

Sound-Path

from

.........

4-24

Measurement

Increased

Sensitivity

Path

4-23 4-23

Sensitivity

. . . .....

.................

4-25 4-26 4-26

.........................

4-27

Butt-Weld Testing With Angle-Beam Transducer Weld Inspection Calculator ....................... Force-Oriented Discontinuity ...................... Amplitude Range of 1/64 to 8/64 Flat-Bottomed

.........

Holes

4-27 4-28 .....

4-30 4-30

Large Discontinuity Indications .................... Reduced Back Reflections from Porosity .............. Irrelevant Indication from Contoured Surface ...........

4-31 4-31 4-32

Grain

4-33

Size

Dead-Zone Long

and

Indications Interference Short

Pulse

Typical Contact Test Effect of Lamination W4d

Indications

Porosity Surface

Using

.......................... ......................... Effects

on Display

4-34 ..............

4-35

Discontinuity Indications .......... on Back-Reflection Multiples ....... Angle-Beam

Contact

and Slag Indications in Weld Seam Crack Indication Using Angle-Beam

4-35 4-36

Technique

.....

4-36

............ Technique

.....

4-36 4-37

V 4-2

TABLE

OF

CONTENTS

(CONT) Page

Paragraph 4-42

Two-Transducer

Figure

4-43

Figure

4-44

Indication of Near-Surface Coarse Grain Indications

Discontinuity .........................

Figure Figure

4-45 4-46

Irrelevant

Indication

from

Cylindrical

Irrelevant

Indication

from

Figure

4-47

Surface-Wave Surface-Wave Indication Indication

Figure

Indic ations

.......................

Long

4-37 ...............

Specimen

Bar

Specimen

..........

4-38

..........

4-39

Figure

4-48

Irrelevant Irrelevant

Figure Figure

4-49 4-50

Irrelevant Irrelevant

Figure Figure

4-51 4-52

Standing Wave Patterns Resonance Test Blocks

.......................... ..........................

4-41 4-43

Figure

4-53

Typical

Display

4-43

Figure Figure

4-54 4-55

Transparent CRT Display

Figure

4-56

CRT

Displays

4-57

Bond

Tester

Figure

Resonance

Table Table

4-1 4-2

Percentage Acoustic

Table

4-3

Resonance

Edge Reflection Indication with

4-38 4-38

from from

CRT

Plastic Loose

Wedge Transducer

...................... Variables ...............

of Discontinuities

Testing,

....................

............................

of Reflection Properties

.............. Crystal

....................

Thickness Scale of Back-Surface Display

.............. Two Transducers

of Materials

......

4-39 4-39 4-40 4-40

4-44 4-44 4-45 4-46

.........................

Constant

. . .

4-46

...................

K Table

.................

4-47 4-48

v_j

2.

2.

PREGED1,NG

£AGF= BLANK

NOT

CHAPTER 400

contact

of ultrasonic

contact

with units,

face

the

of the

usually

close

tance space

These

initial

path

the

a thin

only plates,

units

are

initial

The

water and

with

In the

coverage

for

appears

front

following

paragraphs,

display

or at a dis-

material

through

as a fairly

because

is

unit

is used

immersion

techniques

soundbeam

superimposed

into the

reflection

over

a contact

transducer on the

surface

mounted

the

from as

transmitted

On some

are when

display

a waterproof

in direct

a couplant.

membranes

reflection

methods:

is used

as contact

surface

distance

of contact

film

The

ultrasound

the

of two basic

transducer

liquid

water.

testing,

pulse

the

considered

front

the

one

or flexibIe

than

the

with

in water.

first,

with wear

and

specimen,

with

testing,

other

pulse

or column.

of sound

accomplished

In immersion

test

IMMERSION

1.

of the

wide reduced

techniques

are

following.

TECHNIQUES

GENERAL

Any

one

where

of three

both

squirter

techniques

the

is used

transducer

technique,

water;

where

transducer tube.

tire

technique

A flexible

surface.

the

transducers

the

soundbeam

2.

immersed

in water.

the

glass).

The

the

through

mounted

end

tube

of the

a further

soundbeam

and

like

light

In the

of the

in the top couples

the

beams

axfe

wheel-

of a water-filled unit

is the

wheel-transducer

or

of flowing

is mounted

refinement

(much

bubbler

bubbler

a column

An adaptation

transducer

lower

technique,

in water;

transducer

surface.

techniques,

concentrate

to the

use

when

test

of focused passed

techniques

are

shown

The

technique

transducers both

the

transducer

is directed

through

for

generating

and the

the

concentrated

usually straightdirection.

used and

water

test

specimen

into

the

waves

are

immersed

material,

or one

using

of the

many

In many automatic scanning discontinuities or to define

either angle-

operations, minute dis-

soundbeam. in immersion

angle-beam The

the

longitudinal

for generating shear waves. are used to detect near-surface

with

soundbeam

both

soundbeam

a straight-beam

continuities

TECHNIQUES technique,

beam techniques focused-beams

complTsh

test

immersed

immersed

4-1.

IMMERSED

In the

of these

method:

are

is transmitted

the

on the

immersion

specimen where

on the

is a unit with

a magnifying

in Figure

rolls

membrane

that

test

technique,

that

In all three

through

in the

and

and wheel-transducer

of a liquid-filled

the

TECHNIQUES

In contact

a substance

the

the

discussed 401

wedges,

crystal.

between

velocity

specimen,

together.

from

a water

test

through shows

are

testing.

plastic

transmitted very

testing

or immersion

contact

The

4:

GENERAL

Techniques

the

_ILMED.

water-path

testing testing

are

through

distance

must

straight-beam manipulation be considered

units and

that

ac-

control

of

in immersion 4-5

WATER-FILLED TEST

SPECIMEN

[

0 ,

This

This distance

through

specimen.

pear

on the

tions.

is the

distance

When

metal

path

of the

part,

when

the

in steel. plus

test

area

recording

area shows

of unwanted the

will

water

1/4

velocity appear

front

the

sound

surface

1/4

of aluminum

for

the

water-path

setting confusion

and

screen

setting

oscilloscope

cause

that

oscilloscope

correct

Careful

water

and

is gated distance

4-2.

Water-Path

back or

equal

for is done

Adjustment

surface. through

the

will not surface

steel;

ap-

reflec-

therefore,

to four

one

inches

is 1/4

is particularly

misinterpretation.

Distance

test

soundbeam

to travel

distance,

distance

screen of this

as

the

the

reflection

first

relationship.

Figure

4-6

for

and

to send

is about

The

that

required second

transducer

required

front

on the

on the

of the

ttme

the first

inch.

signals

time the

of thumb

operations.

face the

TECHNIQUE

Techniques

between

A rule shown

path

the

properly,

screen

sound

path

the

so that

than

done

and Wheel-Transducer

between

is greater

In water, of water

Bubbler

adjusted

oscilloscope

inch

and

4-1.

the water

test

WHEEL-TRANSDUCER

Figure

is usually

T .NSO, C

SUPPLY

BUBBLER TECHNIQUE

testing.

TIRE

automatic to clear Figure

of

thickness important signalling the

test 4-2

V

3. The

BUBBLER bubbler

TECHNIQUES

technique

soundbeam

is projected

is usually

used

with

strip,

cylindrical

jected

into

4. The

the

surface

WHEEL-TRANSDUCER wheel-transducer mounted rotate

across

the

is moved

past

ducer.

The

constructed beams 402 i.

it.

shown

of flowing

test

The

of plate,

The and

waves

where

specimen.

scanning

water,

longitudinal

bubbler sheet,

soundbeam

is pro-

is directed

or is adjusted

the

normal at an angle

waves.

of the

through

a water-filled

tire

in the

wheel

axle,

The

wheel

may

4-3

and

is held

illustrates of the

immersion into

test

the

stationary

position,

straight-beams,as

and the

shown

while

in Figure

the wheel

where

moving

on the 4-3,

the

The

apparatus

fixture,

mounting

in that

specimen.

on a mobile

on a stationary

transducer

method

the

in a fixed

be mounted

be mounted

angle

in Figure

CONTACT

for

is an aspect

Figure

to project

as

a column

or it may

position

the

parts.

technique

freely.

material,

high-speed

method,

TECHNIQUES

is projected

and tire

into

for

immersion

regularly-shaped

surface shear

of the

column

system

through test

to produce

transducer,

a water

and other

material to the

soundbeam

that

runs

the

material

wheel

wheel

trans-

axle

may

or to project

be

angled

4-4.

TECHNIQUES

GENERAL

Contact

techniques

soundbeam waves

through

a variation

an automated

forms,

(perpendicular) to the

is essentially

in the

surface-wave

are

wave

mode

test

divided desired:

specimen,

technique

into

for

three

categories,

straight-beam angle-beam

producing

.WATER-FILLED

which

technique

technique Rayleigh

for or Lamb

for

determined

by the

transmitting

generating

shear

waves.

WATER-FILLED

TIRE

are

longitudinal waves,

Transducers

TIRE

TRANSDUCER.

_

/_/TRANSDUCER

,;_ jWHEEL

/

OVER MATERIAL

_--J

MATER,AL MOVESI

Figure

4-3.

Stationary

and

Moving

Wheel

Transducers

--

and used

in

SOUND

BEAM

DIRECTED

SOUND

BEAM

DIRECTED

SOUND

BEAM

ANGLED

IN FORWARD

TO THE

TO THE

DIRECTION

SIDE

SIDE

i

SOUND

PROPAGATED

ANGLE

OF PROPAGATION

=,,,,"

MATERIAL

AT 45 ° ANGLE

90"

AND

FORWARD

ADJUSTING

Figure

INTO

\

4-4.

Wheel

Transducer

POSITION

Angular

MAY

BE VARIED

OF WHEEL

BY

MOUNTING

YOKE

Capabilities

v these for

techniques

are

a eouplant.

The

surface during fer to Chapter couplant 2. The

held

in direct

couplant

contact

selected

the test. For 3: Equipment,

with

is high

the

material

enough

most contact testing, for more information

using

in viscosity the eouplant on contact

a thin,

liquid

to remain

film

on the

is relatively transducers

test

thin; and

re-

s. STRAIGHT-BEAM

straight-beam

specimen

is accomplished

to the

test

surface)

by projecting to obtain

or from intermediate discontinuities. transmission with two transducers,

the a.

technique

(perpendicular

back surface for through interrupt

TECHNIQUES

soundbeam,

Echo

Techniques.

beam ducer and

causing Echo

transducers. in use. With receiver,

surface

is rough

reflections

in the are

received

produced

a beam

of longitudinal

into the

reflections

This technique the internal

test

from

is also used discontinuities

the

to test

signal.

with single

Figure 4-5 shows the single the single unit, the transducer

projecting

receiving echoes lying in the beam

a reduction

where

a soundbeam

pulse-echo

or double,straight-

unit, straight-beam transacts as both transmitter waves

into

the

specimen

and

reflected from the back surface and from any discontinuity path. The double transducer unit is useful when the test or when

the

specimen

shape

is irregular

and

the

back

sur-

TRANSDUCER

I

t I I

Figure face the

is not parallel other

receives,

Is receiving mitter b,

back

unit

shown the

beam

ties

energy

..J

with

the

as

shown

surface

4-7.

transmitter

travels

through

reaching

surface.

in Figure

and

the

Technique

One 4-6.

transducer

In this

discontinuity

over

One

The

path

front

Echo

case,

echoes,

even

the

unit the

opposite

of the the

acts

unit

as a transmitter

projects

receiver

though

material surface

receiving

to the by the

soundbeam

cause unit.

and

a soundbeam

For

best

the

into

opposite

the

other

the

unit

trans-

Any

in the

amount

in this

as a

and the

unit.

results

of sound

technique,

UNIT

// /

/ /

_..-SOUND

\__/

\-

4-6.

Double-Transducer

REFLECTED TO

RECEIVING

Echo

Technique

UNIT

sound

discontinui-

UNIT,_

\\

as

material;

surface;

receiving

a reduction

/

Figure

and

reflectors.

RECEIVING TRANSMITTING

tzansmits

Techniques. Two transducers are used in the technique, one on each side of the test specimen

up at the

in the

..J

is not directly

in Figure

is picked

I I

Single-Transducer

Throu_h-Transmission through-transmission receiver.

I

I

4-5.

SOUND REFLECTED BACK TO TRANSDUCER FROM DISCONTINUITY AND BACK SURFACE

the

TRANSMITTING

UNIT

UNIT

i _DISCONTINUITY

REDUCES AMOUNT

OF ENERGY TO RECEIVING

Figure

4-7.

transmitter unit and the receiver energy. lithium 3. The

predetermined modes

angle

a barium unit.

is used

available generaLor of acoustic energy, best available receiver of acoustic

titanate

to the

in the

test

test

to transmit

surface.

material

Usually,

may

or surface

modes.

Figure fusion

shows an angle-beam unit dead-zone and near-zone

4-8 from

Technique

transmitter

unit

is used

with

a

TECHNIQUES

technique

produced

selected, Is the best unit selected, is the

For example, sulfate receiver

ANGLE-BEAM angle-beam

Through-Transmission

UNIT

shear-wave

sound

waves

into

According

to the

angle

be mixed

longitudinal

transducers

are

used

the

test

selected, and

shear,

in angle-beam

TRANSDUCER

/

Figure

4-8.

at a

the

wave

shear

only,

testing.

scanning plate and pipe material. To avoid coneffects encountered with strai_ht-beam trans-

TRANSDUCER

/

material

\

/ \

Shear-Wave

/

Technique

ducers, this

parts

with

a thickness

less

technique,

the

soundbeam

enters

by successive

zig-zag

deflections

rupted

by a discontinuity

flected

back

unit,

to account

zig-zag

path

welds,

pipe

where

for

are

indicate

taken

by the

angle

surface-wave the

reflected.

For

test

test

403

PREPARATION

1.

test

mine

the

ment

to perform

the test

specimen

requires

that

when

until

all

shear

In

proceeds

it is interand

the

is re-

angle-beam

is reduced are

units.

and

direction

techniques for

angle

placing

which

and

show

for

special

because

used

for

of the

testing

specimens

of irregular

shape

surface.

Angle-beam

trans-

of the

soundbeam

direction

by an arrow

and

waves.

where

angle

are

transducers

where

near-surface

surface-wave

FOR

angle-beam

at a grazing

transducers

or

used

almost

surface

to generate

technique

that all

beam

discontinuities RayIeigh

is shown

project

of the

in Figure

the is

are

surface

waves

4-9.

TESTING

L preparations

begin

technique; the

test.

may the

with

then,

Many unit

an examination components

variables

be too large testing

Figure i

reverses

made

to contact

in steel

specimen

The

appropriate

structures,

unable

specimens

material.

GENERA

Ultrasonic

test

surface-wave

in the

the beam are

material,

angle-beam

boundaries,

Angle-beam

plate

with

at an acute

TECHNIQUES

technique

into

tested

of penetration

markings

of refraction

soundbeam encountered,

are

are

material

specimen

where

length

and

by case

SURFACE-WAVE

the

soundbeam.

sheet units

inch

test

Allowances

effective

or tubing, identified

the

4.

fixed

or boundary

the

5/8

the

from

transducer.

straight-beam

ducers

The

to the

than

4-9.

are

affect

to fit in the is moved

of the

the

selected choice

immersion

to the

Surface-Wave

test

test

specimen

from

available

of technique. tank.

site.

This

In the may

to deterFor

equipexample,

case

of large,

require

portable

Technique 4-11

testing the

equipment.

test

Other

material,

riveted, number

test

etc.), and of identical

technique odd-lot

with jobs

some

study

When

setting

determine

as to the

plate the

common

men

standard

usually

2.

common

defect

test

sonic

plate

are

depth

in the

material,

A sample

test

until

several

a lower

frequency

back

reflections

be necessary

to turn may

In immersion

testing,

other

high-speed

transducer

for

greater

diameter

(no deeper

4-12

than

decreases

rolling

If possible,

in

direction;

a sample

speci-

analysis.

testing.

but

may

specimen

In contact

permit cause

is used

Successively

are

obtained.

testing,

penetration

a loss

10

of ultra-

of near-surface

to evaluate

part

over

lower

If near-surface

and

temporarily,

retest

soundbeam

frequencies

are

resolution

from

following

governed

test

considerations scanning

applied

is required,

the opposite

side,

the low-frequency

by the

2 inches). one

In contact material.

include

to detect

sensitivity as the

transducers,

more directive. relatively thin

in the

in forgings,

discontinuities

transducer (10 to 25 Mc for immersion and 5 to 10 total number of back reflections. If there is no

is largely

for

spreading

etc.

lines;

to

it

or a high-

scan.

optimum

frequency

as determined

paragraph.

transducer areas

elongated

studied

SELECTION

selection

previous

the

be used,

TRANSDUCER transducer

require

is chosen,

example;

flow

Low frequencies

is required.

The

or

will

is carefully For

in immersion

echo,

in the

and crack,

frequency.

back

3.

case

a transducer

specimen

to the forging

to metallurgical

an advantage

sensitivity.

unit

bonded,

One-of-a-Mnd Each

is selected, test

surface

the

frequency

units.

of

covers a large an immersion

suitable.

discontinuities.

penetration with a high-frequency Mc for contact) and observing

may

be

testing

The

parallel

(welded,

testing program is desirable,

may

the nature

technique.

is a longitudinal

maximum

to greater and

to be tested,

SELECTION

the

waves

to the

subjected

frequencies

resolution

found

in pipe and

Mc is usually

of joining

If the record

frequency

or probable

are

FREQUENCY

High

methods

efficient

is established.

parallel

is sectioned

of parts

contact

an operating

discontinuities are

number

recording

portable

practical,

test,

most

and

with

most

up any its

the

roughness,

scanning

be tested

and a reference laminar

surface

are:

the shape of the specimen. parts and a permanent test

automatic

may

factors

in detecting Note

that

with

is raised.

10 Mc and

the

other

angle-beam

possibility

of using

discontinuities;

small

frequency testing,

the

gross

discontinuities

a given For

or,

diameter,

are

used

beam-

of two 3/8-inch

15 Mc frequency, units

a focused

in near-surface

transducer example,

a paintbrush

using

the for

15 Mc unit

testing

welds

is and

4.

REFERENCE

Commercial

ultrasonic

Equipment. acoustic

These

to differ

from

sample

test

determine

the

these

a sensible

for

the

an acceptance

test

its

block

probable

level

is determined in the

test

is determined

by careful

testing

program

is established

by an intelligent

GENERA

this

likely

reason, and

In some

introduced

into

in other

which

establishes

to

cases,

the

sample

specimens.

In all

of the

a

studied

the

number

cases,

sample

the

true

specimen

application

of basic

and

theory.

PROCEDURES L

following

procedures

operator

For

test

are

analysis,

found

study

the

and the

specimen

hole.

specimen.

material

1.

test

are

3:

provided

specimen

discontinuities.

or notches

discontinuities

allowed

test

in the

test

in Chapter

situations,

to metallurgical

of holes with

in detail

in the

discontinuities

and

comparison

many

test

TESTING

with

for

basic

manufacturer

equipment

for

from

form

described

matched

subjected

material

of discontinuities

404

specific

from

in the

studies,

of the

adequate

received

of the

are

or nearly

is sectioned,

as a basis

nature

the

indications

nature

magnitude

are

responses

discontinuities

to serve

standards

matched

cases,

specimen the

artificial

The

standards are

In most

From

reference

properties

block.

and

STANDARDS

immersion

and contact

operating

procedures

Vs operating

manuals

nomenclature

and

used

testing

are

in ultrasonic

is recommended

intended

to familiarize

testing.

Reference

to clarify

variations

to in

design.

r

2. The

TYPICAL following

IMMERSION immersion

of the required assembled

block

simulated

at the

Figure with test

4-10

a 3-inch

a typical

the new

transducer

Connect

the

coaxial

c.

Connect

the

other

Turn

shows

on the for

is adequate operator

end

to the

of the

these

use

for

in this with

equipment

as a

operating

char-

be repeated

scanner

tube.

between

the

to the

procedure

the

procedures

end of the cable

all are

system.

end of the

upper

that system

Equipment,

for

connection

coaxial

assumption testing

is familiar

that

lower

the

3:

immersion

a watertight

cable

with

immersion

to Chapter

it is recommended

b.

d.

Refer

Until

O-ring is in place transducer.

instrument

begins for the

tank.

distance

system,

the

procedure

metal

specimen.

Install

PROCEDURE

of equipment

immersion

acteristics of the several times. a.

testing

components

requirements. A test

TESTING

scanner

Make tube

sure

the

and

tube.

"R"

receptacle

a few

minutes.

on the

panel.

instrument

on and

allow

it to warm

up for

4-13

e,

f.

g.

Place

test

block

in tank

on underwater

Lower scanner tube, by adjusting transducer face is about 2 inches Position

instrument

panel

the manipulator, above the test

controls

(1)

Frequency

- Set to transducer

(2)

Sensitivity

- Low,

(3)

Pulse

Length-

(4)

Pulse

Tuning

(5)

Sweep

- Adjust

(6)

Reject-

Off.

(7)

Sweep

support. into the water block surface.

so that

the

as follows: frequency.

20% of range.

Minimum. - Tune

Delay

for

for

maximum

2-inch

division.

- Set initial

pulse

signal

at first

amplitude.

index

mark

on left

side

of

sc r e e n.

(8) Markers(9) Test

Off.

(Normal

or Through

(io) If required, These (a)

screwdriver

controls Intensity. left

end

nently

if a high screen TANK WITH MOTORIZED

controls

display

require

Adjust

for

long

on the

frequent

minimum

Use

a line

level for

- Normal.

do not

of trace. burn

Transmission)

or

care spot

of brilliant

intensity

may

be adjusted.

adjustment. visible

trace

in adjusting, on the

unit

inner

with

no bright

as it is possible face

of the

is allowed

to remain

at

to perma-

cathode-ray

tube

on the

periods.

BRIDGE

_....._...--SCANNER

.._..__

<_

)! j>_

TEST

Figure 4-10. 4-14

spot

SPECIMEN

Typical Immersion

TRANSDUCER

;ANIPULATOR

SUPPORT

System

TUBE

FOR TEST

SPECIMEN

h°

(b)

Horizontal screen.

(c)

Vertical

Positioning.

(d)

Focus vertical

and Astigmatism. and horizontal

Move

the

is not

transducer

io

the

by the (normal)

top

Observe

from

is used

4-11,

the

surface

j.

pulse

measured

distance

sured

distance

of the

test

left

Observe

the

so that

(FBH).

Adjust

block,

oscilloscope

of the

visible initial

between

the

(2 inches)

on the

screen

the

transducer

of the

line.

the

on both

soundbeam

the

transducer

amplitude shown

unless As

signals

in Figure

screen.

screen.

applicable,

between

as

edge

trace

maximum

(where

of 2 inches

pips

fast-moving

INITIAL

block

test

left

scribe

sharpest

test

off the

right

at zero for

is always and

to the

right

of the

move the scanner distance between

4-11.

This

is the

indi-

more

sweep

de-

shown

in Figure

pulse

is the

first

two pips

is the

water-travel

switch

dial

is the

to Preset) same

face

pips

are

reflections).

PULSE

called

and

front-surface

Some of the as fast as the

water

Adjust

first

frontso that

as the

mea-

the

surface

top

reflection.

tube slightly up and the first front-surface

back reflection remains constant. across the screen at a rate twice

surface

each

at the

block.

manipulator, Note that the __=

of the

distance

sweep

ltne

hole

which

start

to obtain

of the

pip to the The

Adjust

of the

surface

side

tt to the

reflection.

distance. the

the

large

trace

Adjust lines.

surfaces

initial

sweep

flat-bottomed

left

next

Place

an area

pip at the to move

Place

to the

and bottom

the

cation lay

over

interrupted

perpendicular from

Positioning.

the

multiples

down over reflection

and

distance

the

the test block. and the first

observed pips will other indications.

(second

water-travel

Using

subsequent by vertical

move These frontmovement

BACK SURFACE

m

J

L.) L..)

%

I

/TEST

TRANSDUCER

[J r1 . OSCILLOSCOPE

Figure

SCREEN,

4-11.

Transducer

Adjustment,

Normal

to Test

Surface 4-15

of the scanner tube first front and first

so that the back-surface

Adjust SWEEP DELAY and off the oscilloscope

k,

tioned

under

shown

In Figure

the first

to move screen. vertical

the initial The first grid

line

does

not appear

between

pulse and the water path front-surface reflection

at the left

side

of the

the

to the left is posi-

screen,

as

4-12.

INITIAL PULSE

water multiple reflections.

__ -,_

_

TOP

_._-_----'--

]_

SURFACE

SURFACE

OSCILLOSCOPE

Figure ,

Adjust

SWEEP

4-12.

to move

Sweep

the first

first back reflection under screen, as shown in Figure the entire MARKERS. front-surface

TOP SURFACE

width

of the

Align

the

reflection.

Delay back

the last 4-13.

screen. square The

SCREEN

Adjustment

reflection

to the

vertical grid The material

If measurement wave

markers

markers

may

right.

the

is desired,

leading

be expanded

___

edge

SURFACE

PE =

4-16

4-13.

Sweep

Adjustment

turn

on

of the first

or contracted

BACK

Figure

the

line at the right side of the depth is presented across of depth

with

Position

as

V

desired

to represent

Move

m,

the

the test

transducer block

signal

with

acoustic

and the Select tested.

c.

test

specimen.

those

of the

sensitivity

and turn

being

tested

and

case, the

for the

the

the test

from

the

FBH

actual

test has

system

testing

is

may

of material

allow

the

desired and

block

the

type

and

for

reference

Once

on instrument,

two Hitt (distance/amplitude) blocks of the same material a metal

properly,

over

standard

specimen.

frequency

Place Select

have

In this

test

is set

up.

begin.

being

equipment

to

test blocks in the immersion tank. as the material in the test specimen.

distance

nearest

a 3/64-inch

to the

diameter

thickness

of the

flat-bottomed

hole

(FBH).

(Note: If the metal distance of the longest available test block than the thickness of the test specimen, refer to step f.) The

is shorter second block

should

that

match

the first

distance

should

Position

the

off-center, from

the

tiple the

(second the first are

that

the

ducer

of back-surface

instrument

of one

full-height the

the as

For

shown

Adjust

the

water

except

will

FBH

in Figure

top

serve

the

block,

metal

slightly

distance

so that

up and pips

the

same

to produce plus

if the

measured for

the

block.

water

one

height a combined

observing screen

transducer assures

A maximum Move

from

a minimum

at least

the

indication

purpose.

is received

FBH,

pip is 1 inch,

This

of the

and

across

Manipulate

surface the

down

move

pip.

response

sensitivity

example:

surface

reflections.

to the

the

longest

the water-travel

transducer multiple

front-surface

maximum or

of the

to the block

other

pips the

gain

second

3 FBH,

reflection) indication or pip does not appear first back-surface reflections. Water mul-

height

pip from

FBH.

2 inches, inches,

as the

is normal

until

No.

surface

surface.

The

maximum

laterally

upper

by moving

as fast

the

the

transducer

screen.

Adjust from

of the

soundbeam

number

to the

identified

twice

to produce

the

front-surface front and the

oscilloscope

at a rate

over

normal face

including

inch.

transducer

front

pips

block,

be 1/2

and

multiple between

d.

the

is received

sensitivity

forth

from

warm

material

and

of responses

matching

transducer

should

back

SYSTEM

Set up equipment,

One block

the

TESTING

or

a suitable

transducer

material.

response

Increase

IMMERSION

match

gain

maximum

(FBH).

screen.

from

which

in the

oscilloscope

responses

the

the

the

depth

on the

as the

standardized,

b.

THE

until

hole

Move

is defined

properties

a.

bottom

indications

STANDARDIZING

Standardizing block

the

or centimeters

laterally

fiat

amplitude.

observe 3.

inches

the signal

the

trans-

FBH. strength

half-height

second

of the

FBH

first

pip height

pip pip is

of 3

4-14.

L_

4-17

e,

Without

changing

has

1/2-inch

one

and

to the sure

metal

one-half

height previous less

than

)

If the

of the

instrument

setting

specimen,

which

blocks. f.

This

step

test

block

rial

being

is not required

unless

3/64-inch

the d.

observe over

of attenuation. or sensitivity,

ASTM

the

c.

the b.) this,

set

the

height

test

specimen

If there lower

the

frequency,

both

the

test The

drilled

block

in the

over

the

tested.

observe

base,

are

or lengthen

the

mateof

and

With

longest

the

machined this

in

block,

worthwhile,

to make

available

Perform pips.

block

steps Move

the back-surface reflection,

available of the

is manufactured

of back-surface

of back

test

testing.

longest

E 127-64.

being

test

in the

dimensions,

If it is not considered equipment

to detect

thickness

block

Practice

with

blocks,

of the

hole

of the

than

a special

and number and

distance

com-

a matching

area

proceed

in the example:

from be able

material

is a loss

to obtain

Mea-

combined the

(for

thickest

hole

up the

as the

than

step

of the flat-bottomed

Recommended

same

is less

he will

length.

e.

the

that

metal

Due

produced

received

and

of

(Note:

full height.

and in the (f.),

(which

display

step.

pips

pips

block

minimum

previous

are

is shorter

required

test

and compare

sensitivity

operator

step

through

block, the

or

size

flat-bottomed

steps

test

material

ducer

to the

with with

special and

To remedy

diameter

accordance

with

to in step

the

not reach

of both in the

second

previous

of the

signals

to the

following

tested.

height

gain

the

the

material

continue

the proper

equal

(referred

matching

pips

in the near-zone

are

Disregard

may

height

assures

both

pip

displayed

the

whether

FBH

combined

pips

When

discontinuities,

FBH

combined

the

as in the

second

increase

height.

observe

first

and the

FBH

3 inches),

combined

the

with

check

is produced,

of first

pips

and

pips

effect,

step. height

settings,

distance),

height

of these

bined

instrument

FBH

near-zone actual

the

the

pips

c.

the trans-

for

either

increase

pulse

duration,

and

evidence the

gain

until

B FRONT-SURFACE FLAT-BOTTOM BACK-SURFACE

E

FLAT-BOTTOM

WATER-MULTIPLE

.: OSCILLOSCOPE

SCREEN

Figure 4-18

4-14.

JJl

°

IL.

Standardizing

Indications

PIP HOLE PIP PIP HOLE

PIP

PIP

V

several back-surface pips are obtained. Proceed with testing. 4. The

TYPICAL following

required test

contact

area. the

procedure

4-15

shows

is adequate

new

operator

is recommended

that

a.

Connect

b.

Install

PROCEDURE

of equipment

Figure Plate

TESTING

testing

components

Reference Until

CONTACT

use

is familiar

the

the

a typical for

these

begins

for

with

the

cable

a 5 Mc straight-beam,

coaxial

An ASME

several

all

the

assembled Standard test

characteristics

in the Ultrasonic

specimen.

of the

system,

it

times.

receptacle

contact

are

as a simulated

be repeated "R"

that

system

system.

procedure operating

to the

assumption

testing

contact

in this

procedures

coaxial

with the

contact

on the

transducer

instrument

on the

panel.

opposite

end

of the

cable.

c.

Turn

the

d.

Position

instrument

on and

instrument

panel

allow control

(1)

Frequency

- Set to transducer

(2)

Sensitivity

- Low,

(3)

Pulse

Length

- Quarter

(4)

Pulse

Tuning

- Tune

(5)

Sweep

- Adjust

(6)

Reject

- Off.

(7)

Sweep

Delay

it to warm sas

up for

a few minutes.

follows:

frequency

(5 Mc).

10% of range,

for

turn for

1-inch

- Set initial

from

minimum.

maximum

signal

amplitude.

division.

pulse

at first

index

mark

on left

side

of

screen.

/TESTSPECIMEN

COUPLANT__----_'_'_

Figure x_,-

4-15.

Typical

t

II

I1

Contact

II

I

System 4-19

(8) Markers - Off. (9) Test (Normal or Through Transmission) - Normal. e.

Place a few drops of couplant (oil) on edge surface of test plate opposite large test hole. Hold transducer in contact with test block at oiled surface as shownin Figure 4-16. Observe indications or pips appearing on the oscilloscope screen. Move the transducer back and forth over the oiled surface and observe the changes shown on the screen.

f.

Position the transducer over the large hole in the test block and vary the amplitude of the indications by adjusting the SENSITIVITY control. Set control so that the back-surface pip is 3 inches high.

g.

Vary the PULSE LENGTH control and study the action displayed on the screen. Short pulse increases resolution, and long pulse increases penetration.

h.

Turn on the REJECT control and observe the effects on the display. Note that the smallest pips disappear completely when enoughreject is applied. REJECT is used to clip off "grass" or unwantedsignals as shownin Figure 4-17. Turn REJECT OFF for remainder of test.

i.

Move transducer to area of test block where hole reflection pips are eliminated. Only the initial pulse and the back reflection are shownon the screen. Vary SWEEPcontrols to causethe back reflection to move to the left toward the initial pulse. Observe that more pips appear and move in from the right side of the screen, as shownin Figure 4-18. The new pips are multiples of the first back reflection and are equally spaced on the trace. The SWEEP controls may be adjusted to enable the operator to see more time, or more depth in the material. In other words, if the metal distance from top to TRAN_;DUCER _.A..I

O ASME ULTRASONIC REFERENCE PLATE

O

O

II II Figure

4-20

4-16.

Contact

Testing

iI II Reference

II Ii II Plate

COUPLANT

REJECT OFF

ON

Figure bottom

is

6 inches,

of soundbeam j.

Remove serve the (1)

the main Turn

Adjust

as

transducer

trace

Reject

of the

the

is

reflected

test

block

of

line.

beam the

square-wave

Adjust

MARKER

Control

multiples

from

appearance

marker (2)

ten

travel

the

4-17.

FINE

back

reflection back and

markers

markers and

Effects

as

VERNIER

represents

and

turn on

on the

60

inches

forth. the

MARKER.

alternate

Ob-

trace,

below

follows: controls

clockwise

and

observe

widening. the

ALTERNATE

screwdriver, line.

DISPLAY

to position

INITIAL _

the

marker

SHIFT

VERTICAL

trace

just

/BACK

/1/PULSE/

_

" /,_ /SURFACE

control,

below

the

_/FIRST

PULsEINITIA[\f

main

with

a

trace

BACK

_",_ACE

PiP

SWEEP

Figure _-J

4-18.

Back-Reflection

Multiples 4-21

(3)

Adjust

the

ALTERNATE

screwdriver, start (4)

Replace

initial

the

initial

and

of screen,

just

marker

4-19,

appear

transducer

the

for ko

Vary

SWEEP

side the

of the screen

the back sweep more

leading

test

block

the

index

mark

index

mark

on left

waves,

,

sweep

length step

or

I

J

,

area

transducer

UP

' I

4-20.

over

back

initial

pulse

Only

a small

to understand

of the

in Figure the

leading

length

Sweep

delay

material.

the

largest

hole

hole

area

the

in the

signal,

has

I

at

the

area

As to see

viewed

pulse

block,

to be

back

and

in Figure

onto

set

BACK

I

i

Adjustment

the

4-21.

\//_SUR FACE

.....

off

with

screen.

operator

,

Marker

left

material

on the

initial

OFF.

moved

familiar

as shown

PULSE<

switch

the

test

block,

to the

of the

display

by

example,

test

reflection

enables

Move

for

MARKER

reflection

permits

of hole

inch,

to become

the

sweep

a 2 1/2-inch

Figure 4-19. 4-22

Ad-

measurement

and the

Turn

It is important

"i. ",

to the

waves,

I FULL SQUARE

right

side.

and

depth other

waves

the first

i

I

Adjust

shown

pulse

measure

understood.

the

material.

to obtain

I

the

on the

INITIAL _/FIRST

I

a

the

screen.

as

initial

several

square

to move that

and

square

marks,

is visible.

in previous

SENSITIVITY

only

at last

of the

hole

full

controls in Figure

shown

time

edge

where

on the

square

Try

is fully

as

and

full

block

index

Observe

or less

Position

the

distance

limited to a specific the screen. I.

three

screen.

delay

discussed

with

with

shown

at first

of markers.

of scale

DELAY

of the

to coincide

at an area

reflection

until

over

measuring

block are

pulse

two or more

use

marker

control,

reflection.

the number

combinations;

test

back

initial

between

Move

HORIZONTAL

first

reflection

first

controls

of the back

of the

on the

with

edge

counting

start

the back

to position

side

until

the

SHIFT

pulse.

transducer

pulse

SWEEP

(5)

to set

of the

DISPLAY

i

PIP

BACK

SURFACE

PIP MOVED TO LEFT SIDE OF REEN SC _

T A INII L PULSE

/ /

_J!____ ..,__TIM

INCREASED

Figure Move the

the

height

height m,

Turn ject

of signal

affect its

INITIAL

contact

signals,

signal use from

CONTACT testing

Sweep

Delay

smallest

hole

and

make the

to the

repeat

is used,

TESTING procedure

block

and

observe

size

step

lineartty.

test

/

Effect

in Figure

"1. "

of the the

in

that

the

discontinuity.

Observe

that

control

use

of re-

is used

of a discontinuity

to leave test

difference

Observe

reject size

it is best and

the

4-21. of the

The

evaluation

If reject both

shown

is related

amplitude

may

,,,..

EXPOSEDwEEPDELAY _

as

control

it on while

with diffi-

checking

specimen.

PROCEDURE is similar

to the

previous

procedure

used

/HOLE

_

SENSITIVITY

the

amplitude

or impossible. responses

ANGLE-BEAM angle-beam

hole

---_

4-20.

over

on the REJECT may

the

The

of the

discretion; cult

5.

transducer

S

E SEGMENT.

ADJUSTED

FOR 2-1/2-INCH

_,

COMPARABLE

SIZE OF SIGNAL

HOLE

Figure MJ

4-21.

Test

Hole

Size

Comparision 4-23

for straight-beam testing, except that the soundbeamenters the test material at an angle to the surface contacted. An I.I.W. (International Institute of Welding) test block is recommended for use in this procedure as a simulated test specimen. a.

Select a 5 Mc straight-beam transducer and connect it to the instrument coaxial

b.

c.

cable.

Turn on instrument instrument controls (1)

Frequency

- Set to transducer

(2)

Sensitivity

- Low,

(3)

Pulse

Length

- Quarter

(4)

Pulse

Tuning

- Tune

(5)

Sweep

- Adjust

(6)

Reject

- Off.

(7)

Sweep screen.

Delay

(8)

Markers-

(9)

Test

Place

for

up for

frequency

a few

minutes.

Set the

(5 Mc).

20% of range. turn

from

for

maximum

2-inch

division.

- Set initial

pulse

minimum. signal

at first

amplitude.

index

mark

on left

side

of

Off.

(Normal

a few

drops

straight-beam d.

and allow it to warm as follows:

or Through

Transmission)

of couplant

(oil)

transducer

Adjust

SWEEP

across

the

LENGTH

screen

on the so that

as shown

on edge

oiled five

in Figure

©

- Normal. surface

surface reflections

block.

Hold

in Figure

4-22.

of test

as

shown appear

at equal

the

intervals

4-22.

m

m

-

O

_L O--..--------

0

2

"7-4

6

TRANSVERSE

Figure 4-24

4-22.

IIW Test

Block,

Basic

Sweep

Length

WAVES, A

Adjustment

8 IN.

10

e.

Remove the straight-beam transducer and replace it with a 2.25 Mc anglebeam transducer. Reset frequency control on instrument panel.

f.

Place the angle-beam transducer on the test block as shown in Figure 4-23. Note that with the angle-beam unit, the initial pulse is broadened and small signals appear close behind it. This is a result of reverberations within the plastic wedge on the transducer. These signals are normal and shouldnot be confused with signals from discontinuities or the back reflection.

g.

Observe the location of the back reflection received from the test block arc. Note the distance betweenthe 4-inch mark andthe back reflection pip. This is the distance represented by soundtravel in the Lucite wedge on the transducer.

h.

Adjust SWEEP LENGTH so that the reflection from the arc occurs at the 4inch mark. Distance on the screen now accurately represents distance of soundtravel in the test block.

I.

Increase the instrument sensitivity to sucha level that reflections from the 0. 060-inch hole andthe 90° groove in the test block can be recognized.

J.

These

reflections

occur

adjust

instrument

as necessary

in Figure

4-24.

Place

the

angle-beam

block

test

the

8- and

9-inch

to obtain

transducer

in each

4-25.

reflection

ts obtained

to a test

specification,

adjust

the

sensitivity

that

given

In the

Now that

the

Is exactly sweep

and

the

the

of the

in Figure

reflection

Move

marks

similar

positions

transducer,

for

each

sensitivity

on the

indications

maximum the k.

near

until

to those

shown

on the

position,

shown.

control

Re-

indicated

at each

indication

screen.

until

When the

the

working

amplitude

of

specification.

of the

instrument

is standardized

to

m

m

i

4

I

--J

O

"III 0

'III 2

III

II 4

_[I-I 6

1 Ill 8

it11 I0

----I A A = SOUND PATH LENGTH IN LUCITE B

Figure _'_

4-23.

IIW Test

Block,

Lucite

Wedge

Sound-Path

Measurement 4-25

-.

1

k 0

1

2

.3

4

5

6

t'".

7

8

tt

C

Figure the

4-24.

acoustic

may

be

Draw

distance

and of the chalk

along

the

test

the

scanning

along

at

full

specimen

between

the

to the

the

skip

as

transducer

move

scan the

in the

test

scanning

one

center

of the

the

unit

by

at

on 1/2

the

seam.

4-26,

weld.

Contact, must

the skip With

in a zig-zag

Figure

surface until

plate

indications

seam,

the

plate

steel

soundbeam

reduced

weld

from

shown

and

Continue

of the

the

in a steel

butt-welded

distance

to the

to completely

path.

on the

transducer,

other,

Sensitivity

a butt-weld

observing

distance

10

Increased

block, unit

parallel skip

on

mark

test

the and

marks

the

from

angle-beam

plate

centerline

one

steel

Determine

2 chalk

from

couplant,

the

on the

one

Indications

of the

weld.

a finger

screen.

aid

Block,

Place

the

touching

Test

properties

tested.

alongside

the

IIW

9

path

progressing with remain

a discontinuity

a good uniform

is

located.

/ © --

..

L

_.

L

=-

7

Illilll 8

,]-

9

I0

o

1

2

8

9

10

D Figure

4-25.

IIW

Test

Block,

Checking

Sensitivity

V 4-26

_CHALK

Figure I.

The

soundbeam

curately using

path

locate

the

Figure

4-28

tration

shows

The

center

would

shows

Test

in butt-weld

by using

shows

Scanning

testing

a sliding

weld,

The

slider

has

calculator

calculator weld

area

a plan

view

of the

adjusted

time that

works.

of the

been

in Figure

by making

considerable

for

the

4-27.

a scale and

bottom

position

calculator.

To acsketch

unnecessary

is mounted

The

and

is shown at the top. The calculator has of the soundbeam, under the transducer, rule.

Path

is shown

in the

require

how the

a section

area

Weld

discontinuity

trigonometry,

This is avoided duc er. m.

4-26.

MARKS

over

part of the

The

or by effort.

the

trans-

of the

illus-

soundbeam.

instrument

screen

been adjusted so that the entry point coincides with the 0 point on the the

exact

thickness

of the

plate

E - THE ENTRY POINT OF THE SO'UND BEAM. - THE EXACT ANGLE OF THE BEAM. E

i

Figure

T - THE THICKNESS

_

4-27.

__.._

Butt-Weld

Testing

I

with

OF THE PLATE.

_

Angle--Beam

I

Transducer 4-27

OSCILLOSCOPE

SCREEN

_

...DISCONTIN UITY ECHO

,NIT,AL

1t11111

PULSE---__

B I I nl _ " .t

J I

J'

I

, \

I

._

,

I

/

I i

(30mm)

rule.

the same thickness

The

angles

changeable,

4-28.

I

,

"

,I i

I IL •

i

I I''%

I

l_\x

/

DEPTH OF DISCONTINUITY

35MM

I

I ,IDISCONTINUITY

,_ I

,

I

LOCATION

I

/

I '1

Weld with

position

TEST SPECIMEN

Inspection the

of the

in standard e.g.,

INTERPRETATION

Calculator

sloping

line,

discontinuity

representing

is read

the beam

off the

screen,

path, and

at

angle-beam

a 45 ° angle-beam OF

TEST

transducers. transducer

They requires

are

re-

not inter-

a 45 ° calculator.

RESULTS

GENERAL

Ultrasonic

test

usually

bottomed for

indications

related holes

themselves, interpret.

Test

from

the

This

indications

to the

probable

Impedance

of the

material,

of incidence

are

such the may

all considered

type

discontinuities from

standard

or diameters.

shape,

sometimes difficulty

to those

depths

size,

conditions, are

subsurface

or compared

of varying

evaluating

nuities.

4-28

o,,../r_uL._

_----.

OF SHEET

point on the rule, the depth of the discontinuity is read on the scale. These calculators are available for each of the various

fracted

rate

SCALE

I cil_ _

15MM,,.<._/

at Its intersection

on the

are

1 41 ,

I

"

Figure

i.

.

I

I

•

405

_

I_ BEAM PATH ',

/

/

lllJ_"-I

.3_.5/- f

_" TRANSDUCER

r---

I

_I "

"_,.

I

I

as contact cause

used

roughness, evaluating

blocks

and field,

and

phenomena

by experience

of discontinuity when

in the

of ultrasonic with

the

the

to the

contour,

the

and

size

are

in relating

reference

specimen flatfairly

impedance which

surface

test

having

comparisons

orientation,

be resolved

surface

test

These

position,

within

discontinuities are the

difficult

to

ultrasonic

test

attenuation,

location

accu-

of disconti-

conditions. and

of an unknown

angle

discontinuity i

nuity

by its

with

a test

men.

The

from

actual

echo

block

amplitude. similar

experienced

The

in alloy,

operator

defects

and

simplest shape,

also

those

method

is to compare

and back

learns

reflections,

to discriminate

of no interest,

which

are

disconti-

to the

between

called

the

the

false

test

speci-

indications

or irrelevant

indications. 2.

TYPICAL

IMMERSION

Immersion

test

interpreted

by analysis

loss

of back

indications,

reflection,

and

discontinuities

eter,

usually

evaluated

test-block

echoes.

with

the

discontinuity bottom

within

hole

smaller

than

eter,

are

the

distance

small,

As

block,

actual

size.

by the

the

the

is still

meaning;

length

of time

the

in one

plane.

A loss

the

transmitted turned

sound crystal.

nuity

as well

as the

With

relatively

rate

the

the a.

with

Small

discontinuities plane

and

its

during of the

continuity

with

in the

since

from

the

a bit diam-

specimen

while

no quantitative the

extent

the

energy

the

size

of the

that

the

is not reof the

disconti-

discontinuities. the

discontinuity

soundbeam

east

ingot

and

a range

are

its

forces

shown block

rolled,

to the

is not

to the

number are

may

satu-

transmitted

used

in fabricating

4-29.

test

block

The

into

wafer-thin

to orient

Such

the

a discontinuity

relationship

indications

hole

Foreign

tend

part.

discontinuities

small.

or extruded

of the

flat-bottomed

of the

relatively

forged,

surface

in Figure

amplitude

of test

aluminum

are

The

parallel

indication

A significant

of wrought

fabrication.

b. Large Discontinuity with the crystal size, in Figure the

discontinuity while

indication

flat-

the

of the

dis-

is determined

reflections,

as shown

by in

4- 30.

as shown energy,

the

of a

and

is evidence

so that

small

surface

crystal

indicate

not determine

with

Indications.

testing

discontinuity

indication

comparison

pared

used

reflection,

Discontinuity

ultrasonic

Figure

no back

does

the test

has

does

diamechoes

is generally

the

reflection

or reflected loss

method

discontinuities,

in ultrasonic or porosity

fiat

this

the

block

than

over

amplitude

of back

crystal

discontinuity

is maintained

or absence

test

larger

article.

test-specimen and

of the

are

the

transducer

specimen

is moved

case,

of the

discontinuity.

encountered materials

that

refracted,

comparison

test

are

a discontinuity,

surfaces

of the

of the

crystal

amplitude

the

surface

size

In this

Evaluating

large

display

through

maintained.

is absorbed,

to the

of the

Discontinuities

distance

with

units,

from

the

amplitudes

as the

estimated

an indication discontinuity

surface

as smooth the

from

compared the

pulse-echo

of reflection

of discontinuity

are

not

on A-scan

amplitude

by comparing

test

evaluated

displayed

factors:

that

it are

in the

INDICATIONS

generally of three

Individual are

TEST

still

partial may receiving

4-31. or total

Indications. usually produce Since loss

be determined an indication.

the

Discontinuities an indication

discontinuity

of back If the

reflects

reflection

by measuring

that are large, when comthat saturates the display, nearly

is typical. the

discontinuity

distance

all The

the

of the dimensions

transducer

is not fiat,

sound of the is moved

but is three4-29

!

FRONT SURFACE

BACK SURFACE

_DISCONTINUITY

/

\

DISCONTINUITY

_o_ _r-_'_\ Figure dimensional, over close

and

the scanning

together,

from

of the the

is suspected,

Force-Oriented

Discontinuity

third

may

back

dimension

side.

the

article

__o_c_

Indication

be determined

If the

possibility

may

be tested

by turning

of two discontinuities, from

all four

2/64

3/64

4/64

5/64

6/64

7/64

8/64

4-30.

Amplitude

Range

of 1/64

to 8/64

Flat-Bottomed

the

article lying

sides.

1/64

Figure 4-30

extent

4-29.

_

Holes

BACK

FRONT SURFACE

SURFACE

FRONT SURFACE

DISCONTINUITY

I

llll

/I I

FAE

A

Figure c. portant case,

Loss when

it occurs

among

porosity, indications

of Back

the

4-31.

Large

Reflection. in the

causes

Evaluating

absence

of very a sound

or loss

Indication

loss

of significant

of reduction

and a dispersion received from

Discontinuity

of back individual

of back

fine precipitate test specimen,

reflection,

reflection

is most

discontinuities. are:

particles. Figure and the indications

large

imIn this

grain

size,

4-32 shows the displayed from a

FRONT SURFACE

---J

I,---

SOUND

TEST

SPECIMEN

•

j

FRONT SURFACE

\

BACK

SURFACE

/

POROUS TEST

Figure v

4-32.

Reduced

SPECIMEN

Back

Reflection

from

Porosity 4-31

similar specimen with porosity. are reduced considerably. d.

Irrelevant

it is a good

rule

Note that the back reflections from the porous plate

Indications.

When

to be suspicious appearance

of all

amplitude

and

Reflections tween the

from fillets and concave surfaces front and back surfaces which are

discontinuities.

while

These

is the

same

as the

given

distance

time

within

indications

required

for

the

test

surface,

the

amplitude

moved

over

flat

area

the

flat

indication toured

from surface

suspected

signal

in localized

be shielded

piece

of sheet

sharp

spike

edges

of rectangular

within times

machined from

are

a discontinuity, was

increase.

a reflection

edge

moved

edge

finish, located over

SURFACE IRREVELANT

the

from

indication soundbeam

with

with

no loss

usually

occurs

part.

Articles For

spurious about

with

example,

indications 1/3

the

surface

BACK

SURFACE

which

article

depth,

plate,

the

object

pips, of back

the

shiny

were

4-32

4-33.

Irrelevant

Indication

from

as a the

are

surfaces

aluminum

is will

some-

plate

to be reflections received. remained

As the rela-

AT POINT A TO ELIMINATE

__CONTOUR

A Contoured

Near

transducer

TRANSDUCER /

Figure

surto a

reflection,

when

m

A

con-

of the

such

surface.

indication

//"'_'_

the

as contrasted

POINT A

[

over

a contoured

a foreign

METAL SPOON IS INSERTED IRRELEVANT INDICATION

,.

of the

as the

/

v

is

amplitude

around

appeared

of the

a con-

to be consistent

a thick

of the

from

is strong

smooth,

with

which

at a

amplitude

back

a contoured

reflections,

at a time

discontinuity

Broad-based from

befrom

transducer the

as the

an actual

of indication

of the

as the

Reflections

4-33.

displayed reflections

results

time,

tend

in

specimen.

received

transducer

will

surface. the

indications.

test

indication same

be irrelevant,

consistent

a discontinuity

to decrease

to be reflections type

may

the

sound

diminish

Moving indication

in Figure

likely This

to false

to a smooth

shown

shapes,

of the

rise

transducer FRONT

as

observed.

1/2-inch give

At the

off by interrupting

metal, or pip,

sometimes

will

contoured

over

from

If a suspected

or false

the

from

to return

surface.

Where

along

result sound

flat-area

that

unusually

may result in responses sometimes mistaken for

indication

will

the

are

is passing

front

an irrelevant

is moved

may

area

indications that

of the

of the

cause

the

specimen.

increases.

areas,

transducer face

will

transducer

spurious

toured

the

the

considering indications

Surface

tively

uniform

surface nearby thin

film

by coating

case,

the

type

of indication

surface,

the

fiat,

smooth

base

line

angled-plane of the

f.

principal

surface

of the

produce

but lie

display

possibly

surface

with

results

reflecting

wax

discontinuities.

to cause

crayon

from

from

a

or a very

surface,

fit this

gain

transducer

to strike

is manipu-

the

the that

indication

because

of the

category,

and

In this

discontinuity

have

a relatively

moves change

tend

their and

setting

its magnitude.

discontinuities

is moved

forgings

The

soundbeam

large

to the

transducer

high

to evaluate

the

With

at an angle

in large

at a comparatively

discontinuity,

plane.

as the

Bursts

along

the

in distance

to lie

at an angle

surface.

Grain

illustration,

area

is intended

to the

travel.

initially

the

manipulation angles

to scan

to detect

around

of 45 ° to the

©

it is best

sensitivity),

of sound

eliminated

this

smooth

jelly.

Usually, later,

fine

are

Apparently

extremely

Angled-Plane Discontinuity Indications. Discontinuities oriented with plane at an angle to the front surface _ire sometimes difficult to detect

lated,

may

They

magnitude.

on the

of petroleum

evaluate.

at right

and

generated

edge.

e. principal (high

in shape

waves

Size

"hash" note

Indications. or noise

the

grain.

In some

FRONT SURFACE

_

clear cases,

Unusually indications,

indications

large as shown

received

abnormally

grain

large

size

in Figure

from grain-size

the

same results

in the 4-34. type

test

specimen

In the

same

of material

in a total

loss

with of back

BACK SURFACE

FINE-GRAIN STEEL

FRONT SURFACE

(FROM PHOTOMICROGRAPHS)

__"HASH"

SURFACE

/

COARSE-GRAIN STEEL

Figure 4-34.

Grain Size Indications 4-33

reflection. These conditions are usually brought about by prolonged or improper forging temperatures, or high temperature during hot working and subsequentimproper annealing of the test specimen. 3.

TYPICAL

Contact

test

cussed

CONTACT

indications,

in the

discussion

to recognize reflection,

major

factors

after

plastic

testing.

As

in immersion

of the

the

test

material,

initial

can

separation

may

"tail"

of the

the

With

be effective

to the

initial test

Typical

water

of these initial

to those Little

to immersion

when

pulse.

dead which

indications.

path.

near-surface where

Discontinuity

is the

the

length

testing, Only

the

loss

of the

of

article

are

front

displayed pulse

all

in contact

near-surface are is near

INITIAL PULSE

such

obscured of long and the

of as a

testing.

indications,

Shortening

a comparison

Typical

because

In as shown

discontinuities

interference.

discontinuity

path,

is separated

a standoff,

surface

discontinuities

soundbeam

are

by inserting

the

shows

Indications.

of the

initial

be achieved

obscures

4-36

and variadifficult

amplitude,

surfaces

no reflections

initial-pulse

Figure

specimen

zone

transducers,

of the

signal

the

dis-

additional

display.

responses

pulse

straight-beam

because

from

In immersion

pip by the

testing,

pulse

during

pulse.

testing,

discontinuity

The

4-35.

b.

similar

Indications.

to detect,

applied

are

Dead-Zone

contact

difficult

indications

contact

distance

front-surface

in Figure

indications.

of the

block,

most

or identical

test

in evaluation

by the

the

similar

the initial pulse at the front surface of the test specimen of coupling, produce irrelevant effects that are sometimes and

entering

are

on immersion

used

obstruction from

when

in contact

back

instances,

paragraphs

be given

Interference from tions in efficiency

INDICATIONS

in many

previous

will

a.

TEST

the

may

be

initial

by the ringing short

pulses

surface.

indications

encountered

in ultra-

_IBACK \/"

_/,.SU RFACE

TRANSDUCER_ f /_II DEAD

FRONT

SURFACE_

_

I

ZONE

.r

r

\

Ir

TEST SPECIMEN

Figure

4-35.

Dead-Zone

Interference _

4-34

I

i -

_BABLE RESONANCE LONG

PULSE

,SCONT,NU,TY TEST SPEC,MEN

IITY

SHORT PULSE

Figure sonic

testing

ure

4-37,

include

such

Laminations

4-36. those

from

as shown

and

Short

inclusions,

sheet

and

in Figure

Pulse

discontinuities

as nonmetallic

in rolled

multiples

Long

plate

4-38.

found seams,

are

in forgtngs,

the

plate and view B shows a reduction in the distance when the transducer is moved over the lamination.

welds,

a satisfactory

as shown zones,

in view

commonly

tions

as shown

shear

A of Figure

but in this

seam

wave

case, has

4-39.

discontinuities 4-40.

PULSE

with the

View

weld

B shows

such

as porosity cracks

transducer,

are Figure

from

slag

which

the

weld.

fusion

The

produce

detected

shows

indicated,

for

of the

a

reflections testing of

clearly

reflections

sometimes 4-41

reflection

received

zones

center

and

in Figand flaking.

between the back In angle-beam

O

D

in back

same

in the

shown

cracks,

display

fusion

the

is located

Surface

an angle-beam

I

INITIAL

is shown

a discontinuity

in Figure

with

area

as

bursts,

by a reduction

A illustrates

normal received

weld

on Display

forging

shown

View

Effects

indica-

when

using

a surface-wave

I

B

weld a

indi-

D

B

REFLECTION DISCONTINUITY

1-11 NON-METALLIC INCLU$1ON

Figure

4-37.

17K] _., #1 CRACK

SEAM

Typical

Contact

Test

Discontinuity

FLAKING

Indications 4-35

kj

VIEW A

Figure

4-38.

Effect

VIEW B

of Lamination

on Back-Reflection

WELD

Multiples

NEAR EDGE

DISCONTINUITY FAR EDGE

A

Figure

4-39.

SEAM

Weld

POROSITY

B

Indications

Using

Angle-Beam

Contact

Techniques

SLAG

\ \

Figure 4-36

4-40.

Porosity

and

Slag Indications

in Weld

Seam

cation

from

a crack

in the

surface

using

two transducers,

the

tion,

as with

transducer.

the

a relatively ducers beam initial

single

thin

are when

test

used

immersion

testing.

inch

the

below c.

across

Figure

surface

width

4-42

does

shows

the

in the

4-43

shows

wedge

gives

same

way

pitch-and-catch

not interfere indications

Paired

resolution.

Lucite

The

time

water-path

an indication

from

recep-

received

angle-beam

transit

an additional the

testing, with

from

trans-

of the

sound-

advantage

in that

separation

occurs

a discontinuity

only

the in

0.02

material.

Indications. of the

With

pulse

two transducers.

left

of the

Irrelevant the

using

the

to the

specimen.

Figure

near-surface

through

is moved

test

or transmitted

specimen,

to improve

passing

pulse

of the

initial

Coarse-grain

display,

as shown

material

in Figure

causes

4-44,

when

INITIAL

reflections the

test

or

"hash"

is attempted

PULSE

CRACK

IRFACE WAVE INDICATION

g

Figure

4-41.

Surface

/TRANSMITTING

Crack

Indication

Using

Angle-Beam

Technique

/RECEIVING TRANSMITTED

PULSE

TRANSDUCER_TRANSDUCER DISCONTINUITY //?,',

/ ,,_-__

ECHOES

/ ',,;,, / II

_\

/ /

\

ENTRANT

I

"-..

I

\_

,BACK SURFACE REFLECTION

II \

/ \/

ULTRASONIC TRANSDUCER TO ENTRANT

BEAM

REFLECTED

BY A SURFACE

AWAY NOT

FROM

PARALLEL

SURFACE.

Figure r

TO SURFACE

RETURN TO TRANSDUCER,

',-Y- / I I

FROM

SURFACES PARALLEL

4-42.

Two-Transducer

Indications

•

kj

4-37

DISCONTINUITY

0.02"

BELOW SURFACE

BACK REFLECTION TRANSMITTED

TEST

Figure

SURFACE

4-43.

Indication

Figure at a high lower

frequency. When

transducer surface conversion turning

To eliminate

the frequency

transducer.

4-44.

and

change

testing

of Near-Surface

Coarse or reduce

the

cylindrical

curved

to fit the

test

appear

as shown

in Figure

occurs

from

straight

soundbeam

ducer.

Surface

the

shear will

waves

soundbeam waves,

lessen generated

effect

of the

surface,

problem

during

of these

additional

when pips

In testing

the

sides

in Figure by changing

face

test

to a larger also

of the

the

back-

specimens,

A more

testing INITIAL

the

an angle-beam

following long

of the

4-46.

reflections,

by using

especially

straight-beam

unwanted

soundbeam

4-45.

striking

as shown this

Indications

specimens,

will

as reflected

the

direction

is not echo

Grain

Discontinuity

specimen diameter cause

4-38

Irrelevant

Indication

from

Cylindrical

Specimen

trans-

unwanted

PULSE

ADDITIONAL (SPURIOUS) REFLECTION

4-45.

and re-

directive,

DIRECT REFLECTION

Figure

mode

INITIAL PULSE BACK

REFLECTION

LONGITUDINAL

S H ER____,..__ A

Figure irrelevant Figure face

indications 4-47.

wave

to move

with

wave

component 4-48.

Irrelevant

when

Movement

testing Figure

4-46.

they

of the

across

the

This

reflect

display

from

from

the

will

with

the

transducers,

soundbeam

type

Indication

transducer

two straight-beam of the

:TED SHEAR WAVE INDICATIONS

_.,_

edge

Bar

of the

cause

the

movement to the

reflection INITIAL

test

of the

specimen

as shown

caused

by the

transducer.

to have

receiving

is easily

Specimen

indication

it is possible

transmitted

of unwanted

Long

unit

a small as

recognized

in

sur-

When surface-

shown

in

by varying

the

dis-

PULSE SURFACE WAVE

REFLECTION

Figure

4-47.

Irrelevant

Surface-Wave

Edge

Reflection

INITIAL

TRANSMITTER.

....

PULSE

IRFACE WAVE INDICATION

_ RECEIVER ..___=_-__ .

i Figure

4-48.

Irrelevant

Surface-Wave

Indication

with

Two

Transducers 4-39

tance between the transducers and watching the indication; when the distance is increased, the apparent discontinuity indication moves away from the initial pulse. Using angle-beam transducers, a certain amount of unwantedreflections are received from the wedge. These indications are shown immediately following the initial pulse in Figure 4-49. Whenthe transducer is lifted off the test specimen, the reflections from within the wedgeare identified becausethey are still present on the display. With continued use, the crystal in the transducer may come loose or fracture. When this happens, the indication is characterized by a prolonged ringing which addsa "tail" to the initial pulse as shown in Figure 4-50. As the prolonged ringing effect results

in a reduced

is discarded

capability

of the

system

to detect

discontinuities,

the

or repaired.

INITIAL

WEDGE REFLECTI(

I

I Figure

4-49.

Irrelevant

Indication

from

A

Figure 4-40

4-50.

Irrelevant

Plastic

Wedge

B

Indication

from

Loose

Transducer

Crystal

transducer

406

RESONANCE

1.

TECHNIQUE

GENERAL

The

resonance

two

sides

plane

technique

smooth

as the

and

test

surface.

or fundamental

resonant

as

beam

a continuous

surge

of increased

thickness, men;

frequencies;

length resonant

and

As

amplitude

the

frequency frequency

when

in the

is varied occurs frequency

at some for

the

to the from

(or its

and

standing

frequencies

are

the wavelength

thickness

of the

waves

cause

over are

test

speci-

a range set

shown

of

up within

in Figure Since

the

a

material

into the

decreases.

material,

is applied

checking

to vibrate

same

a characteristic waves

transmitted

with

in the

multiples)

When

are

transducer

point,

has

standing

indications.

several

of material lying

material

specimen,

waves

is increased,

related

measuring discontinuities

frequency test

received

is determined TEST

this

to the

by causing

thickness detect

of a given

of longitudinal

patterns

are

for also

thickness

energy

beam

Standing-wave when

each

frequency,

resonance

specimen.

primarily but it will

of sound

a continuous

the wavelength

As shown,

is used parallel,

the

4-51. wave-

fundamental

the formula:

SPECIMEN

REFLECTED

TR SDUCER

WAVE

/

1 MEGACYCLE

INCIDENT WAVE

F

(FUNDAMENTAL

FREQUENCY)

L_-----------_.-------_""'" THICKNESS

= 1/2 WAVELENGTH

(2ND HARMONIC) 2 MEGACYCLES

-----,,--

(3RD HARMONIC) 3 MEGACYCLES

THICKNESS

------..

__

THICKNESS

4 MEGACYCLES (4TH HARMONIC)

= 1 WAVELENGTH

[_

= 1-1/2

,,x..s,

WAVELENGTHS

_,,x,.7,_1 I

-,------

L

--

Figure

4-51.

THICKNESS

Standing

= 2 WAVELENGTHS

Wave

Patterns 4-41

/ i

V F

---

m

2T

Where:

With its

instruments harmonics

difference

ments,

the

actual

CRT display, ments require

V

=

velocity

T

=

thickness

material

(CRT)

in the

display,

as pips.

any

frequency

off.

The

two adjacent

the

fundamental

The

chart

or K table

frequency

velocity

material

into

the

K factors

of each

given

readout

any

from

is also

and

used

frequency

is

instruover

the

Other instruTo use these harmonics

the

is

corresponding

for frequency-thickness

K factor

table

and

a scale

two adjacent

or table;

frequency On most

light display. the thicknesses.

constant

in the type

resonant or pips.

a direct

between

on the

A constants the

given

fundamental

harmonics

are

difference

is located

in inches. wave

waves

or a scale over a stroboscopic of charts or tables to compute

by dividing

longitudinal

resonance

of the material.

measurements

frequency

is read

for

of longitudinal

screen

between

the

the

conversion

on the

thickness

or tables,

frequency

an oscilloscope

a meter, the use

determined;

of the

fundamental

appear

the

thickness

____

using

always

charts

F

are

to obtain

derived

of material,

the

thickness

by dividing

in million

inches

the per

second,

by2. 2.

TYPICAL

In the

following

operator 3:

has

RESONANCE resonance assembled

Equipment, a.

for

Turn

TESTING testing

the

requirements and

a suitable

display. c.

Adjust nesses

d.

Place For

e.

f.

oscillator

4-52

transducer example,

the

transducer

the display,

difference

Assuming

the

and

between fundamental

determine

any

resonant

compute the thickness by using the the following values for K and F: 4-42

on test test

indications

the

block

and

the

opposite

observe

blocks.

selected

Of steel

fundamental

the known

for

this

thick-

exercise.

plate. resonant

frequency

harmonics).

Zrequency formula

on the

match

or plate

thickness

two adjacent

Connect

transducer

reference

of sheet

1/4-inch

the to Chapter

equipment.

and

install

that

Refer

up a few minutes.

typical

on a section a standard

is made area.

it to warm

place

shows

of the

instrument until the thickness marked on the test block.

Observe (the

allow

assumption at the test

description

couplant,

Figure

the

equipment

and

on instrument

Using

procedure,

necessary

coaxial cable to the end of the cable. b.

PROCEDURE

tobe T

0. 461 megacycles K = T and substituting V

_'_/

REFERENCE BLOCK

Figure

BLOCK

4-52.

K

=

0. 116

(steel

F

=

0.461

megacycles

Resonance

constant

obtained

from

(fundamental

3.

TYPICAL

Resonance frequency display.

Two

(fundamental

T

0.25

=

RESONANCE

instruments and

0. 461

its

TEST

using

harmonics

resonance

an on

indications

K table) frequency)

(constant

K)

resonant

frequency)

RESULTS

oscilloscope the

Blocks

resonant

0. 116 T (thickness)

Test

screen are

as shown

(CRT)

display,

pips.

Figure

projecting

show 4-53 above

the shows the

fundamental a typical

horizontal

CRT sweep

7 RESONANCE INDICATIONS

/-

CRT SCREEN--_..

HORIZONTAL SWEEP

,w/

Figure *.-_

4-53.

Typical

Resonsnce

CRT

Display 4-43

line.

Their

height

represents

signal

strength

the base

line

is a function

of frequency.

designed

for

the

under

test,

scale

shown

readout made

material

is obtained. for

The

aluminum

and

covers

or amplitude,

By placing over

the

their

a transparent

face

of the

superimposed

a range

and

the

along

thickness

CRT,

over

position

a direct CRT

of 0. 090 to 0. 180 inch.

scale, thickness

in Figure

The

2nd,

4-54,

3rd,

is

and

.133

CRT SCREEN-. .. I

.140

150

.160

170

Y

180

ill II'lllllJllllJlllir I _!_J_L-JJ 3RD HARMONIC

090

,ll_0

_L.LJ._L LL [__LI I

,Ii0

120

,130

2ND HARMONIC HORIZONTAL

ALUMINUM

Figure are

right

indication

since

it appears

for

detecting

by reduced various

4-54.

shown.

is read once

The as

for

corrosion,

_J_LL_L.LLU_LI

[-J--[--[_ .090

each

thickness.

back-surface

THICKNESS

Transparent

].I ,0

.II0

.120

left

indication

indication.

is read

conditions.

as 0. 100 or 0. 133 inch,

CATHODE-RAY

thickness

thickness

shows

smooth

j,

Scale

correct

by a decrease 4-55

Where

TUBE

The

Resonance

is indicated Figure

IN INCHES

Thickness

0. 100 or 0. 148 inch.

which

material

CATHODE-RAY

. 160 .170

150

SWEEP ,,_

4th harmonics

.1,LO

llfilJl llJJJlIIlJ Illlll,lltJlJillIl

I I i il

three

surface

and

testers

are

also

in signal

amplitude

different

CRT

displays

sharp,

strong

produce

TUBE

the

is 0. 100 inch,

CATHODE-RAY

used

caused from indiTUBE

TRANSDUCER /

SPECI_/../

/

SPECIMEN \

[_

TRANSOUCER

H SMOOTH SURFACE

Figure 4-44

4-55.

CRT

VARIABLE

SURFACE

Display

of Back-Surface

PITTED

Variables

OR CORRODED SURFACE

cations,

variable

duced

surfaces

amplitude.

resonant

frequencies. instruments

resonance

indications.

from

a plate

direct

screen. by

honeycomb

Usually

is

it is

CRT

ing

the

tester

size

are

test,

of the function

is below

Lack empty an

is

the

good. minimum

simulate

ultrasonic

as

four

detecting

bond

testers

and

has

to

represent

obtained

high is

from

over

or

Indications mean

the

test

disappearance

the

areas

in

quality

or

By

size,

the

test.

made

The

a given

material

characteristics

adjustpattern

under within

the

A typ-

4-57.

specimen

standards,

physical

along

for the

mismatch.

of known

size,

up on

discontinuity.

impedance

a bonded

set

bond

indicating

a void gage.

moved

appearance

in Figure

reference

the

is appearing

shown

a given

The possible

instrument

to a laminar

a very

of the obtained

substandard for

re-

of

ultrasonic

locations

is

the or

used

similar

tester

requirements.

by

and range

indications

transducer

or

bond

Indications

as

or

The

are

is

with

indications

voids

to a "GO-NO-GO"

closely

strength

the

a wide

detected

resonance as

frequency

over

resonance

indications

pattern, responses

similar

in the

For

of bond

space

resonance with

considered

must

or from

compared

bond

tested

a void

or

of the

structures,

material.

pattern size

then

bonded

of the

also

several

indicated,

indications.

signals

of discontinuities.

three

are shifting

of the

or

soundness

ical

a sudden

some

types

with

are

shows

of varying

weak

changes

4-56

various

Discontinuities

specimen, or

observing

measuring

indications

produce

discontinuities

Figure

containing

thickness

of all

by

several

surfaces

Gross

resonance

CRT

produce

Corroded

being up

for

of the

each

bonded

i ! CONDITION TRANSDUCER

TEST

CATHODE-RAY SOUNDPLATE L

SPECIMEN

TRANSDUCER STRADDLING EDGE OF DISCONTINUITY

lie [UJ_

DISCONTINUITY AT 1/2 THICKNESS

NJ

DISCONTINUITY AT .3/4 THICKNESS DISCONTINUITY AT A SHARP ANGLE DISCONTINUITY AT 1/4 THICKNESS DISCONTINUITY CLOSE TO THE SURFACE

Figure

! R_

i

4-56.

CRT

Displays

of

Discontinuities 4-45

SCREEN RESONANCE

Figure specimens

being

tested

and

also

4-57.

Bond

must

have

Tester

clearly

Display marked

"void"

and

"non-void"

areas. 407

REFERENCE

In the

follo_ing

TABLES reference

is an indication

of high

density,

and

Constant

K values

acoustic

tables,

a high

impedance impedance

of various

are

4-1.

of acoustic

Longitudinal

given

materials

Table

percentage

mismatch.

in Table

are

given

Percentage

4-2

and for

in Table

reflection,

Table

shear

velocities,

a number

wave

4-3,

of materials.

for

resonance

of Reflection L_J

FIRST MEDIUM

ALUMINUM STEEL NICKEL COPPER BRASS LEAD MERCURY GLASS QUARTZ POLYSTYRENE BAKELITE WATER OIL (TRANSFORMER)

4-46

z _J o,:,

z

21

24

18

0.2

0.3

0

0.8

O

(..)

0

14

3

1

2

0.3

50

42

72

74

1

9

16

31

27

77

76

88

89

2

12

19

34

29

79

75

89

90

0,2

7

13

19

22

75

71

87

88

O

5

I0

23

16

73

68

86

87

0

1

9

8

62

55

79

80

0

4

1

8

6

75

76

0

0.8

40

32

65

67

O

46

17

O

4-1,

68

71

1

12

17

0

18

23

0

0.6

testing.

Table 4-2. Acoustic Properties of Materials

LONGITUDINAL

MATERIAL

DENSITY VELOCITY P=GM/CM 3 VL=CM/_SEC.

WAVES

IMPEDANCE ZL=GMX1000/ CM 2 - SEC.

SHEAR WAVES VELOCITY VT=CM/,uSEC.

SURFACE

IMPEDANCE i ZT--GMX1000/ CM 2 -- SEC.

VELOCITY VR=CM.bSEC.

WAVES IMPEDANCE ZR=GMX1000/ CM z - SEC.

i

AIR ALUMINUM 2S0 ALUMINUM 17ST BARIUM TITANATE BERYLLIUM BRASS (NAVAL) BRONZE (P-57o) CAST IRON COPPER CORK GLASS, PLATE GLASS, PYREX GLYCERINE GOLD ICE LEAD, PURE MAGNESIUM, AM 35 MOLYBDENUM NICKEL OIL, TRANSFORMER PLASTIC (ACRYLIC RESIN-PLEXIGLASS) POLYETHYLENE QUARTZ, FUSED SILVER STEEL STAINLESS 302 STAINLESS 410 TIN TITANIUM (TI 150A) TUNGSTEN WATER ZINC

.033 .635 .625 .550 1.280 .443 .353 .450 .466 .051 .577 .557 .192 .324 .398

.033 1,720 1,750 310 2,330 3,610 3,120 2,960 4,180 12 1,450 1,240 242 6,260 400

11.4 1.74 10.09 8.3 .92 1.18

.216 .579 .629 .563 .138 .267

2,460 1,010 6,350 4,950 127 320

2.20 10.5 7.8 8.03 7.67 7.3 4.54 19.25 1. O0 7.1

.153 .593 .360 .585 .566 .759 .332 .610 .518 .149 .417

1,300 3,800 4,560 4,550 5,670 2,420 2,770 9,980 149 2,960

.001 2.71 2.80 .56 1.82 8.1 8.86 7.7 8.9 .24 2.51 2.25 1.261 19.3 1.00

.290 .279

788 780

•310 .310

840 868

.871 .212 223 .240 .226

1,600 1,720 1,980 1,850 2,010

.787 • 195 .201

1,420 1,580 1,780

• 193

1,720

.343 .344

865 765

.314 .313

765 698

.063 .287 .311 .264

717 499 339 2,320

.339

745

.279 .312 .216

2,180 2,500 2,290

.279 .265

1,420 5, i00

.120 • 199 .070 .310 .335 .296

2,320 199 798 539 3,650 2,610

.i12

I32

.375 .159 .323 .312 .299 •167 .512 .287

825 1,670 2,530 2,500 2,290 1,235 1,420 5,520

.241

1,710

-

°

E

i

4-47

Table

4-3.

Resonance

MATERIAL

QUARTZ SILVER STEEL, CAST STEEL, STAINLESS STEEL TEFLON TIN TITANIUM TUNGSTEN TUNGSTEN-SILVER URANIUM WATER (FRESH) ZINC ZIRCONIUM

Constant

CONSTANT

K Table

K(1,000,

O00 IN./SEC.)

0.121 - 0.131 0.188 - 0.193 0.252 0.086 - 0.092 0.0695 0.087 - 0. 110 0.092 - 0.093 0.010 0.114 0.Iii 0.064 0.078 0.047 0.049 0.114 0.116 O. 124 0.106 0.108 0.113 0.115 0.026 (APPROXIMATELY)

ALUMINUM ALUMINUM OXIDE BERYLLIUM BRASS BRONZE (P-5%) CAST IRON COPPER CORK GLASS, PLATE GLASS, PYREX GOLD ICE LEAD MAGNESIUM MOLYBDENUM MONEL NICKEL PETROLEUM PLASTIC(ACRYLIC RESIN, POLYETHYLENE PHENOLIC LAMINATE(PAPER RUBBER

Testing,

PLEXIGLASS) BASE)

0.0525 0.036 0.052 0.0205 0.I14 0.071 0.II0 0.116 0.I12 0.114 0.i15 0.I18 0.0245 - 0.0335 0.065 0.121 0.126 0.102 O.076(APPROXIMATELY) 0.066 0.070 O.028(APPROXIMATELY) 0.082 0.093 0.102

=

4-48

V

=

CHAPTER

5:

C

CALIBRATING

TABLE

OF

TESTING

UNITS

CONTENTS

Page

Paragraph 500

GENERAL

501

STANDARD

L

C

REFERENCE

1.

General

2.

Materials

3.

Shapes

TYPICAL

502

.........................................

5-3

BLOCKS

........................

5-3

.......................................

5-3

......................................

5-4

........................................ CALIBRATION

1.

General

2.

Area/Amplitude

3.

Distance/Amplitude

4.

Transducer

5-4

PROCEDURE

.....................

5-6

....................................... Check

.............................

Check

Check

...........................

5-1

Standard

Reference

Blocks

Figure

5-2

Standard

Reference

Block

Figure

5-3

Typical

Figure

5-4

Steel

Figure

5-5

Typical

Figure

5-6

Figure

5-7

Transducer Transducer

Area/Amplitude Area/Amplitude

Distance/Amplitude Axial Beam

5-7 5-8

................................

Figure

Bail

5-6

5-10

.......................... Design

Response

5-3

......................

5-5

Curve

5-8

Response Response

.................

Curve Curve

................

5-9

..............

Distance/Amplitude Characteristics Pattern ..........................

5-10 ........

5-12 5-12

!PRECEDING

PAGE

BLANK.

CHAPTER 500

calibration

Iinearity

of dispIayed

rant

effects

within

to reference operator

size

calibrated

Techniques)

of material

sample

whmh

as nearly

unit

Once

testing

standard,

ment

system

and

501

STANDARD

the

adjust

TESTING

UNITS

proper

the

unit

of discontinuities to values reference

the

dimensions

When

of the BLOCKS

test

blocks, and

of the

instrument (Figure

performance. the

to the

test

sample

test

system

standards,

the

of the

is done

properties sample

to sample

test

sample.

mateStan-

(refer

in a specific

to calibration

IrreIe-

instrument

values

the

made

physical

is given

to establish

to known

within

of the

acceptance attention

to standardizing

instrument

is calibrated

special

considerable

required

by calibrating

or standardize

matches

REFERENCE

is frequently

eliminated

equipment

instrument with

units

to ensure

are

display

as possible.

rigid

and

testing

an accurate

the 4:

testing

indications the

confidently

expect

dardizing

For

CALIBRATING

of ultrasonic

standards. may

and

Chapter

1.

[:ILI_ED.

GENERAL

Periodic

rial

5:

NOT

to

shape of the

is based of the

and

test on a

instru-

variables.

5-1)

GENERAL the

purpose

of equipment

Figure

calibration,

5-1.

Standard

ultrasonic

Reference

standard

Blocks

reference

blocks

are

manufactured hole

drilled

Alcoa,

into

one

Automation

dards. and

in various

shapes

end.

for

tude

checking

Distance/amplitude

consists

for

sources

instrument

such

blocks

performance

of the

same

of the

lengths.

steel

calibrating.

in the bottom For

Area/amplisize,

shape,

of each

block.

same

further

as

stan-

of varying-diameter when

of blocks

varying E127-64.

from

checking

diameter

flat-bottomed

to as off-the-shelf

of a series

in a series

size

available referred

of eight

but with Practice

a standard

in couplant

of varying made

diameter flat-bottomed holes, refer to ASTM Recommended 2.

readily used

of a series are

with

and are

and immersed

holes

blocks

are

standard,

consist

flat-bottomed

each

etc,

blocks, pins

blocks

with

blocks

reference

on steel

reference

sizes,

Inc.,

reference

mounted

length,

These

Industries,

A fundamental

balls,

and

shape,

and

same

information,

MATERIALS

Ultrasonic standard reference blocks are made

of carefully selected aluminum

alloy

bar stock (refer to ASTM Recommended Practice E127-64). Various other types of blocks are made from plastic, steel, magnesium, carbon, etc. When

testing materials, sensitivitycorrections and adjustments for metal distance

are most reliable when nearly matches

made

on special reference blocks of a material which most

the material of the test specimen.

When

of the reference block used for checking performance

calibrating, the material

of the equipment

ent than the material found in subsequent test samples.

may be differ-

In such cases, the equipment

is standardized to the variables of the material under test, as described in Chapter 4, Techniques. 3.

SHAPES

(Figure

Standard

reference

shapes.

Commonly,

rection both

and area

accuracy

one

and

blocks

aw

are

usually

two sets

set

for

responses diameter,

which

for

Area/Amplitude

blocks

are

usually

to a depth hole

inch

increments;

hole

bottom

or 5-4

The

cutter.

for

The

inch,

hole

which

1/64, bottom

pins

flat

cor-

which are

consists

on steel

combines

checked

for

of a series and

immersed

standard

or cylindrical

of in

reference

blocks

with

shape as the others in the set. The drilled in the bottom center of each

perpendicular set

set

blocks

Area/amplitude and hole

or cylindrical

area/amplitude

A basic

of rectangular

is made

for

Reference

mounted

in each

example: block

finished

are

same size of the one

diameters

in each

set

standard,

in sets

the size

of 3/4

one

Standards.

made

each block as nearly only variable is the

in rectangular

used;

be used.

reference

Shapes

block.

are

correction.

may

a fundamental

of varying

block

manufactured

of blocks

distance/amplitude

distance

by using

steel bails, the couplant.

5-2)

to the vary

2/64,

in a progression 3/64,

by final is made

longitudinal etc.,

drilling as smooth

axis

of 1/64th

to 8/64 with

of the

inch.

a flat-end

as possibIe

The driI1 and

is

HOLE PERPENDICULAR TO TOP SURFACE (A). HOLE BOTTOM (C) PARALLEL WITH TOP SURFACE (A).

f-

--,-----2"

TO 2-1/4 DIAMETER

A = ULTRASONIC ENTRY SURFACE. B = METAL DISTANCE. 3 INCHES FOR AREA/AMPLITUDE BLOCKS, VARYING DIMENSION FOR DISTANCE/AMPLITUDE BLOCKS. C = FLAT-BOTTOM HOLE SURFACE. D = BACK SURFACE. PARALLEL WITH TOP SURFACE. E = HOLE DIAMETER. VARYING DIMENSION FOR AREA/AMPLITUDE BLOCKS IN ]./64-INCH INCREMENTS, 5/64-INCH DIAMETER FOR ALL DISTANCE/AMPLITUDE BLOCKS. ]./4-INCH FLAT COUflTERBORE FOR PLUGGING HOLE.

w-----" A

1 1fc

B(SEE

NOTE)

3/4"

'_''E (SEE NOTE)

Figure

v,j

Standard

parallel

to the

top surface

the

bottom,

when

hole

lated

to the

height

at a constant bottom. tude fiat

ends

made

are

corporations

protrude

2 inches

diameter

The

same holes

diameter, sized distance

surface

shape

as the

drilled

With

blocks,

others

fiat-bottomed,

to a constant

diameter,

of the

bottom

one 1/16

the

block

of the

press-fit

each

standard pins

of the block. the

set,

3/4

of each

inch

oscilloscope the

except in depth. pip

The

diameter,

tops

the

with pins

that block As

block are each

are

installed

of the pins

parallel

instrument

of the eight

size

hole

as an area/ampli-

area/amplitude

inch

of

is located

size

used

immersed,

over

center:

from

with

area is re-

bottom

to area

by eight side

the

is

pin tops.

Standards. Rectangular or cylindrical are made in sets with eachblock

in the

and

hole

also

to 1/2

block,

transducer

in the bottom

hole

from rod,

later,

oscilIoscope,

an unusual

pierced

of the

the

for Distance/Amplitude to area/amplitude

use

block,

drill

of the block.

the

each

related

steel

by centering

As

diameters,

to the

Shapes similar

or amplitude,

be seen

on the

is directly

to the

calibrated

As will

displayed

pip size

perpendicular surface

Design

of varying

Various

which

and

of a long

of standard

Block

of the block.

of the pip

bails,

consists

Reference

reflected

distance,

Steel

standard.

which

b,

5-2.

height

blocks, as nearly

is varied.

usually

5/64

hoie

bottom

is

related

to the

is directly

inch

top surface. 5-5

502

TYPICAL

i.

GENERAL

In the

following

conditions

and

a.

Test

CALIBRATION

paragraphs,

a typical

equipment

Any

testing

b.

Test

c.

Transducer.

of several

The

test

will

commercially

frequency

An immersion

operational

procedure

be covered,

assuming"

available

pulse-echo

instruments.

Frequency.

Power

ealibl_ation

as follows:

Instrument.

ultrasonic

d.

PROCEDURE

frequency

Source.

shall

transducer

be 15 Mc.

of 3/8

inch

diameter

quartz;

with

an

of 15 Mc.

Line

voltage

with

regulation

ensured

by a voltage

regulating

transformer. e.

Immersion large block.

f.

Tank.

enough

Couplant. the

fine

Blocks. area

hold

transducer

the

couplant and the

as a couplant.

comparing

and

area

distance

and

Test

are

containing

diameter blocks

The

and

Reference an alternate

balls,

quality,

ranging

free

device, tank.

a 3 inch length

from

for

water,

from

at

differing

set

for

example,

metal

When and

as a tee pin,

which

5/64

blocks

diameter

is necessary

ASTM

dis-

inch

set

-,

both basic

are

3/64

compared

5/64

are

set

-,

and

compared

diameter

holes.

area/amplitude

re-

described marks

other.

and

combines

the

and

calibrating

surface

to 1 inch

distance

relations

contain

to each

relations

distance

which

normal

an area/amplitude

A basic

Area/amplitude

and provides

metal

by using

set.

reference 1/8

are

be used;

Standard. to the

such

that

Distance/amplitude

of corrosion

in size

planes

is the

and to hold

ASTM

set

of bali-bearing

in 1/16

inch

each

increments. ball

is

reference

same

responses

transducer

corrections

blocks.

holes.

of varying

15 steel

may

reference

the

accomplished

responses

blocks

Fundamental

sensitivity

a distance/amplitude

of ten

8/64-inch

supports

in two vertical

responses

of blocks

A suitable immersion

is used when

adequately

adjustment

continuity

sponses,

of the

will

The bridge is strong enough to support the maniputo allow smooth, accurate positioning of the trans-

manipulator

Reference

consisting

i.

water

is used

that

blocks.

angular

between

positioning

deaerated

temperature,

The

between

is satisfactory

accurate

Bridge and Manipulator. lator and rigid enough ducer.

h.

to allow

Clean

same

reference g.

Any container

in the

of

2. The

AREA/AMPLITUDE linear

from

each

alternate

range

of the instrument

of the

area/amplitude-type

for a.

CHECK

the

reference

Place

a No.

inch

the

is adjusted gage b.

sIightIy

the

crystal

proves

block.

ultrasonic may

responses

be used

as an

A maximum

the

transducer

at a water

surface

a 5/64 over

distance

of the block.

of 3 inches

This

of 1/32

inch,

of the

block,

the

distance

by using

a

crystal.

the

the

Position

containing

to the

front

surface

soundbeam

number

surface

reflection

is perpendicular

of back

surface

to obtain

of the

block.

to the

top surface

reflection

pips

a

This of

serves

the

purpose.

Move

the

hole

transducer

laterally

the

instrument

gain

obtainable

on the

cathode

remaining

blocks

in the

Replace

the b.

reference

and

distance which

c.

for

a water of the

shown,

straight

line

plotted

below of the

cation

above

to the

ideal from

The

point

per

cent

response

the limit

is received

from

The

height

(AH) is the

same

difference

height

height

this

other

blocks

in the

are

maximum

step

for the

the

set.

Repeat

Maintain

No.

7 and

in the

No.

a water 8 blocks

the the

factor

the

corrected

of indication

the

example}

corrected (CF). the

corrected

and

curve

are

different

factor

(CF)

is not constant. indication

height

increased line

up-

is intercepted. (CI-I) in

instrument

(CH) and

each

linear of indi-

of indication

the

a

in the

a vertical

ideal

height For

correction

deviation

range

height that

are

Amplitudes

by projecting until

In the from

Amplitudes

is required.

is done

5-3.

deviates

instrument.

(in this

of indication

curve

in Figure

of responses

in the non-linear

This

range,

is displayed,

the

as shown curve

response

defines between

indications.

for

of linearity

amplitude

correction

because

except

the

point

in the non-linear way,

repeat

the

and no correction

of interception

play.

indication

where

curve.

actual

is 31% of the

Do not

of 6 inches.

of linear

the limiting the

block,

limit

instrument linearity

pip height

of the

record

indications

point

of maximum

indication

each

the

each

and

distance

defines

the

screen.

with

block

recorded

the

until

tube

block

of 3 inches

a curve

ward

maximum

set.

each

example

range

the

control ray

for

require

Plot

until

bottom.

Adjust

the

the balls

(a block

off-center, the

normal

from

block

a + or - tolerance

and the

that

(steel

tank.

and

within

transducer,

pip height

steps

f.

block,

of the

indication

the

e.

of the

maximum

same

d.

immersion

the block

Manipulate

the

c.

in the

accurately,

between

reference

hole} face

blocks

as follows:

5 area/amplitude

surface

between

by obtaining

reference

blocks}

diameter

upper

is determined

can

the

dis-

actual

amplitude is plotted When

the

in actual

is computed

100

(,,,

I

z o

I

i

AH = ACTUAL HEIGHT CF = CORRECTION FACTOR

IDEAL LINEARITY_

F--

/

< CH = CORRECTED HEIGHT ----- 80 -ADD CORRECTION FACTOR z__ TO ACTUAL HEIGHT TO uJ OBTAIN CORRECTED HEIGHT -J m AH + CF = CH

8/64"

°

o<

60

_lw,./

DIA-CHJ

--

f

t

/

I

7/64"

CF

DIA- CHm/_

,v

...eA-cg

.---

AH

6/64"_ 40 '< _;

5/64,,mA

t._

z

,,DIA

4/64

20

/

/

_,_,"

"_LIMIT

OF LINEAR RESPONSE

_ POINT OF STANDARDIZATION

J"

I

3/

I

l

NOTE:

LU n,-

,,, o_

" .._'2/64" DIA 0 4"1/64" DIA 0 10

IN THIS EXAMPLE, INDICATIONS WITHIN +5% OF IDEAL ARE CONSIDERED LINEAR. I I I I 30 40 50 60

20

RELATIVE (RATIO:

by adding follows:

5-3. the

AH The

linear

is used,

gain

control

constant

steel

instrument

may

steps

a.

is adjusted screen

ball.

For inch

ball. 5-4.

indication

height,

as

also

be determined

through until

except

the pip height

wtth each

f., the

bail,

and

the

The

recorded

transducer the water

transducer

by recording

ranging in size The immersion that

in step

is 50% of the positioned distance

is positioned

indications

are

the from method

d.

the

maximum over

the

is mainfor plotted

maxion a

CHECK

characteristics

on a curve,

actual

each of fifteen steel balls, in 1/16 inch increments.

at 3 + 1/32

from a 5/64

to the

Curve

CH

response from each as shown in Figure

distance/amplitude

Response

directly

oscilloscope

diameter

the ultrasonic responses ing metal distance with recorded

=

previous

DISTANCE/AMPLITUDE

are

factor

of the

following

inch

Area/Amplitude

responses from inch in diameter

on the

mum curve

tions

CF

obtainable tained

The

+

instrument 1/2

Typical

correction

range

ultrasonic 1/8 to 1.0

3.

AREA UNITS

1/64TH = 1, 2/64TH =4, 3/64TH = 9, 4/64TH = 16, 5/64TH = 25, 6/64TH = 36, 7/64TH =49, AND 8/64TH =64. DYNAMIC RANGE: 64 TO 1, INTERMEDIATE PIP HEIGHTS IN PROPORTION)

Figure

gi

70

each inch

of the

instrument

are

determined

by obtaining

of the reference blocks in a set of blocks diameter hole in each block. The resultant

in the

following

procedure:

of varyindica-

1:: LLI AH = ACTUAL HEIGHT CF CORRECTION FACTOR CH = CORRECTED HEIGHT ADD CORRECTION FACTOR

80_ 70 --

O9 Z O w }-<

IDEAL LINEARITYn_

CH I_ CF

_)

/9

."'-

_CSy P.....

TO ACTUAL HEIGHT TO OBTAIN CORRECTED HEIGHT , AH + CF = CH

/ /

I

6O

m Z

/

LINEAR

S

5O

RESPONSE

h3 .-J

OF STANDARDIZATION J

4O

C* < t_ ,v

/

,f/7

/.

3O

f.-

NOTE: IN THIS EXAMPLE, INDICATIONS Wl [HIN +5% OF IDEAL ARE CONSIDERED LINEAR,

#

2O

I0

-_

i/8

1/4

3116

5/16

3/8

7/16

1/2

9/16

BALL DIAMETER,

Figure a.

Place

distance immersion

block,

slightly

from the

Position

off-center, and

the

the

of the

of 1/32

inch

7/8

15/16

1

block.

Curve

tothe

over

distance

inch,

13/16

flat-bottomed

top surface

transducer

at a water

surface

Response

a 5/64

tank.

a + or - tolerance the

containing

3/4

INCHES

Area/Amplltude

of 3. 000 inches

crystal

the

hole

upper

of 3 inches Adjust

by using

hole

with

bottom,

in

surface

between

this

distance

a gage

between

a

of the the

face

accurately, the

block

crystal.

Manipulate

the transducer,

maximum

pip height

indication

proves

block. purpose.

Move

the

hole

Replace steps b. distance

bottom.

the

the

Adjust

reference

and c. for of 3 inches

to the

front

number

the

block

the

instrument on the with

of the

reflection

is perpendicular of back

until

obtainable

surface

surface

soundbeam

laterally

maximum

the

from

that

transducer

25% of the

normal

A maximum

same

the

d.

bIock,

of the

of the

c.

Bail

within and b.

Steel

a reference

metal the

5-4.

5/8 11/16

each

surface

maximum gain cathode of the

block,

of the

block.

to the

top surface

reflections

response

control ray other

to obtain This

serves

is received

until tube

the pip

a

height

the

from is

screen.

blocks

each block and record the indications. for each block, except when the basic

in the

set.

Repeat

Maintain water set is used, which

requires diameter Plot

e,

a water distance of 6 inches for one block containing hole with a metal distance of 3. 000 inches.

a curve

example

4.

of the

shown,

indication

to the

increases,

the

TRANSDUCER

To improve of the

accuracy

A beam

testing ducer

than

in this

be calibrated

with

Transducers.

In the

lOO

i TEST

90 Z O

m r_ Z

t FREQUENCY:

from

can

also

zone

in Figure

extends

or decrease

5-5.

from

As the distance

the

beyond

In the

0.5

inch

2.0

inches

in height.

not valid the

the

characteristics

instrument,

are

determined

a 1/2

inch

if the

one used

I 15 MC

from

steel the

that

the

ball

and

the

used

commercial for

with

for

the 6:

transCali-

checking

i

TRANSDUCER: .?,/8-1NCH - DIAMETER QUARTZ WATER

80

1

DISTANCE: I

3 + 1/3,2 INCH 1

[

/

70--

W .J rn 60

....

W r_

50

40 h O W "i b-Z

rw W

30

F

/_

20-

IO

POINTOF

/

STANDARDIZATION

/ 0.5

1.0

1.5

2.0

---..,

/ -

2.5

3.0

METAL (INSTRUMENT

Figure 5-10

5-5.

Typical

3.5

4.0

DISTANCE,

CORRECTED

4.5

5.0

5.5

6.0

INCHES FOR

Distance/Amplitude

NON-LINEARITY)

Response

of

ultrasonic

in Chapter used

plot

analysis

accuracy,

apparatus

at a

beam

A complete

maximum called

procedure,

curve

by

immersed

steel

is subsequently

with

equipment

ball

same

the

procedure.

To ensure

special

diameter

transducer

in this

be accomplished

following

i

calibration,

test

to remember

procedure. the

equipment by the

be obtained

It is well

cannot

used

test

or distorted

are

other

characteristics

brating

ultrasonic

or plot

procedure

equipment may

(fresnel)

attenuate

of 3 inches.

instrument

transducer

indication.

curve

pattern

distance in this

test

field

inch

during

a distance/amplitude

any

near

2.0

as modified

in water. recorded

the

as shown

inch

CHECK

transducer,

water

indications

indications

recording fixed

recorded

an 8/64

Curve

6.5

7.0

the

transducer is the same as that prescribed in the previous paragraphs for calibrating the instrument with reference blocks. The maniuplator is set to allow a range in water distance of 0 to at least 6 inches from the face of the transducer to the ball surface. a°

Adjust

the

instrument

obtainable water

on the

distance

surface this b.

point

After

control

ball.

the

until

screen

of 3 + 1/32

of the

by locating

gain

oscilloscope inch

Exercise

transducer

from

the

care beam

the pip

with

the

height

face

of the

in producing

center

transducer

a true

on the

center

maximum

positioned

at a

to the

maximum of the

top

indication

ball.

Record

of standardization.

standardizing

the

instrument,

set

the

water

Again, exercise care in using the manipulator beam center on the center of the bail. Record Do not

is 50% of the

transducer

readjust

the

instrument

gain

control

distance

at 1/4

to locate the the maximum

in this

inch.

transducer indication.

or succeeding

steps

of

the procedure. c.

Vary the water inches. Record tance, center

d.

As

distance in 1/8 inch increments through a range of 1/4 to 6 the maximum indication for each increment of water dis-

using care each remains centered shown

in Figure

non-Iinearity) sponse The

e.

plot

5-6.

tances

of 1.25,

and

an acceptable

distance

for

and

the

recorded

the particular that

occurence

axial test

peaks as

beam

for

in the

curve

The

curve

dis-

deviation

in

inch.

Determine the transducer beam pattern by relocating the manipulator obtain a 3 ± 1/32 inch water distance from the 1/2 inch diameter steel to the

face

travel,

of the

the

height

ducer

passes

The

symmetry

scan

transducer. of the

over

by rotating

should

not

vary

soundbeam. profile

which

30 per

cent

the

of the

indication

ball.

the

transducer than

has

side

lobes

magnitude transducer

from

the

distinct

is checked

more

of the

scanning

Three

beam

An acceptable

of an acceptable

While

laterally, bail lobes

45 degrees.

10 per

cent

transducer with

will

the

is shown

center

in Figure

The 5-7.

beam

the

are

trans-

observed.

displacing of the

perimeter than

to bali

total

while

a symmetrical

no less lobe.

scans;

magnitude entire

produce

magnitudes

of the

inch

or maximums four

The

about

3/8

is observed

by making

test. in

at water

allowable

is 1/16

in the shown

occur

any re-

used

to the

peaks

the

(corrected

instrument

shown.

of these

that

distance/amplitude

is similar

the

3 inches

back

indications the

transducer

It is important 1.75,

the

is moved

to demonstrate

transducer

for

Figure water

5-6,

on a curve

of the

curve

time the transducer on the bail.

20 nor pattern

side

each lobes

of the beam more

than

or plot

8O

7O

V

60 POINT OF z O I h<

J

STANDARDIZATION

50

z i LLJ .J

40

,¢ t-_ .¢ hi P/

30

2O

10

illllll

A -

0

I

2

3 WATER DISTANCE,

Figure

5-6.

Transducer

Axial

.......

5

6

INCHES

Distance/Amplitude

110

O I

4

Characteristics

C/L (CRITICAL

POINT)

101

t,I f_ U.z i_e," -rn,-

w

J

BO

\ IMERSlON TRANSDUCER - 3/8-INCH DIAMETER QUARTZ, WITH OPERATIONAL FREQUENCY OF 15 MC.

70 60 50

TARGET - 1/2-INCH DIAMETER STEEL BALL AT A WATER DISTANCE OF 3 ±1/32 INCH.

w_ e_- z

40 ZI.W<

..30

SIDE LOBE MAGNITUDE SHOULD BE 20%-30% OF CENTER LOBE.

AJ

'22 1/16

\ 1/8

3/16

1/4

5/16

3/8

(INCH) TRAVERSE ACROSS FACE OF CRYSTAL

Figure 5-12

5-7,

Transducer

Beam

Pattern V

CHAPTER

6:

CALIBRATING

TABLE

OF

TRANSDUCERS

CONTENTS

Page

Paragraph 600

GENERAL

.........................................

601

GENERAL

EQUIPMENT

602

GENERAL

CALIBRATING

603

TRANSDUCER

6O5

QUALIFICATIONS TECHNIQUE

CALIBRATING

1.

General

2.

Test

3.

Function

4.

Recording

6-3

.....................

EQUIPMENT

6-3

..................

6-3 6-3

Setup ......................................

6-4

....................................... Method

6-4

.................................

5.

Manipulative

Reflector Targets ................................. Pulser ........................................

6-6 6-6

8.

Wideband

6-6

1.

General

2.

Flat-Disc

3.

Focused

Equipment

6-4

6. 7.

Receiver

.............................

6-5

................................

System .................................. OF TRANSDUCER BEAM

PROFILES

..............

....................................... Transducer Transducer

Measurements

.................... .....................

4. Cylindrically-Focused Transducer ANALYSIS OF TRANSDUCER DATA

Measurements .......................

1.

General

2.

Waveform

6-6 6-7 6-7

Measurements

6-7 6-7 ...........

.......................................

6-7 6-9 6-9

......................................

6-10

......................................

6-10

3.

Frequency

4.

Damping

5.

Sensitivity

6.

Focal

Length

7.

Beam

Amplitude

Profiles

8.

Beam

Width

Symmetry

Factor

..................................

6-10

.....................................

6-11

.................................... and

6-1

Equipment

Figure

6-2

Camera

Recording

Figure

6-3

Figure

6-4

Typical Flat-Disc

Transducer Transducer

Figure

6-5

Focused

Transducer

Figure

6-6

Cylindrically-Focused

Figure

...................

.......................................

9. Display RECORDING

604

6-3

Functional

6-11

............................ ...........................

Diagram Method

6-11 6-12

.......................

6-4

...........................

6-5

Data Sheet ....................... Measurements ....................

6-8 6-9

Measurements Transducer

.................... Measurements

6-9 ...........

6-10

V

-PRECEDING PAGE BLANK CHAPTER 600

transducers,

specification, because

601

Specialized is excited

and and

beam

GENERAL

In general, tank;

a ball

bearing,

the

transducer

of the

formation

relating

transducer

moving

tiometers,

and

produced

by use

these

be used 603

for

1.

exist

or backing,

and

is required

for

accurately

characteristics,

not distort are

the

natural

amplified

manner

the

distortion, a perma-

instrumentation

recording

factor,

of

provide

special

and

damping

will

crystal

mode

without

which

describe

or caltbrating

the

transducer

beam

size,

beam

sym-

TECHNIQUE consists

post,

over the

RF

to the

frequency,

over

related

the

signal

camera.

materials

or articles.

More

ampli-

recorded

test

for

With

equipment,

of the beam

uniform

on the

is analyzed

manipulative

in specifying

beam.

At the highest

of the unit.

recording

immer-

ultrasonic

is photographically

sensitivity

precision

used

in profile.

in the is produced

RF waveform

and

a dynamic are

response

waveform

unrectified

using

circuits,

CALIBRATING

by the

beam

of the

measurements

inspecting

is scanned

plot

damping,

of an open-shutter

reflector

a changing

The

target,

delay

a smalI

reflector,

return

stationary.

of using

or a thin wire

the

held

TRANSDUCER

pages

sensitivity,

a flat

beam,

recorded

will

in some

following

as a distance/amplitude

portion

may

anomalies

to lens

equipment

transducer

measuring,

technique

is moved

with

same

distance.

calibrating

tude

when

The

as frequency,

the

oscilloscope

bond

transducer

that

by the

CALIBRATING

transducer

receiving

is displayed for

focal

of poor

To analyze in a fashion

record. such

Acoustic

to the

assembly.

and

received

techniques

characteristics

As the

spike

received

photographic

areas

manufactured

QUALIFICATIONS

variables.

signals

and

characteristics.

cutting,

transmitting

by a voltage

equipment

in-

the

data

poten-

symmetry

resuIts

may

or selecting

is

be expected

transducers

to

EQUIPMENT

GENERAL

Equipment sonic

used

transducer

screen, the

TRANSDUCERS

in appearance

transducer

wideband

information

metry,

in the

EQUIPMENT

The

the

individual

transducer

operation.

identical

in crystal

of parts

measuring

602

have

of variations

GENERAL

nent

though

usually

misalignment

sion

CALIBRATING

GENERAL

Ultrasonic

and

6:

NOT FILMED.

of the

transducer

distance/amplitude An open-shutter

to accurately is capable signals over

sent the

plot camera

measure

the

of reproducing and

received

reflector. of the is then

an exact by the

With soundbeam used

send-receive

characteristics indication,

potentiometers is produced

to record

on the

transducer.

the

The coupled

on the beam

of an ultraoscilloscope

system to the

also motion,

oscilloscope

profile

moves

on Polaroid

a

screen. film. 6-3

2.

TEST

The

SETUP

transducer

is placed

Lucite

or

glass

so

plant.

A reflector

the is

in a couplant immersed

placed

transducer

ensured

by

crossfeeds

convert

motion

position tance are

controls

produced

3.

by

6-1

a timer,

transducer

simply

and

soundbeam

of milling

data

into

The

in inches.

switching

to a small reflector

with

table

accurate

motion

which

horizontal

viewed

of the

are

fed

oscilloscope

X or

made through

into

the

the

horizontal

shows

of crystal

V cou-

scanning on

display

Y directions

of the

Potentiometers

signals

Either

aquarium)

are

crossfeeds.

electrical

oscilloscope.

an 4.

Figure

shows

a functional

delay

unit,

with

crystal. at

in the use

traverse

(similar

dis-

movement

potentiometers.

FUNCTION

Figure of

of the

of transducer

the

tank

transducer

a sharp

In operation, adjustable RECORDING 6-2

shows

and

spike the

time,

diagram

pulser,

later

and

timer triggers

of the wideband

then

instrumentation receiver.

amplifies

triggers the

return

both

the

equipment, The

unit

signals

delay

unit

fed and

which

repeatedly

the

consists

pulses

back

the

through

pulser

tube

the which,

oscilloscope.

METHOD how

the

response

curve

is

recorded

with

an

open-shutter

camera.

I DATA

SWEEP DELAY

[

PLATES HORIZONTAL

I
:0 _

TIMER

I

SCOPE

I 1PULSER I

VERTICAL PLATES

RECEIVER WIDEBAND

TRANSDUCER

Figure

6-1.

Equipment

Functional

Diagram

I

The

data

potentiometers,

oscilloscope

screen.

produced, beam.

as variations

a lock-open

Precision

length

screws

are

of data

trace

has

per

division

transverse across

fitted

the

or disturbing

with

slides,

the

and

and

port

table

the

across

response

of the

use

while

soundsuch

dimensional

is a scope-mounted

for

is

transducer,

and

the

curve

uniformity in the

chain

drives

then,

non-

Polaroid,

photographing.

required

for

precise

are

used,

which

that

of an inch.

develop

micrometer

screen;

the The

movements,

recording

two data are

to the

other

one,

of the

beam

profile

soundbeam consist

Two

delay

sweep distance

is calibrated

a plot are

of the

to the

potentiometers,

mounted

recordings

of the

the

reading

by switching

Two

mounting

the

oscilloscope.

longitudinal

are crossfeeds

in thousandths

oscilloscope

of the

on the

is obtained. the

of the

composition,

system

mechanisms

By relating

bezel

one

target

a viewing

calibrated

sprocket

across

on the

record

lens this

Milling

potentiometers.

and

plot,

and

RF presentation

abnormalities

thickness, for

the

describing

to specific

and transversing screw

moved

a permanent

camera

measurements.

micrometer

to delay

EQUIPMENT

elevating

and focal

first

crystal

shutter

used

of an inch

is related

MANIPULATIVE

heavy

method,

A recommended

featuring

are

in thousandths

information in damping,

uniformity.

use

By this

calibrated This

5.

as shown,

so that rotated made

one

slide

by the the

in inches one

on the

plot

is made

90 ° from without

of

the

turning

transducer.

UTTER

TRAVERSE ACROSS TARGET

SCOPE

POT _ii_l _

DATA

DELAY ACROSS SCREEN

Figure

6-2.

Camera

Recording

Method 6-5

6.

REFLECTOR

Unless

reflector

targets

signal

and

used,

particularly

selected

will

of the

This

will

ment

of the

produce

post,

ball

as small

of ball

reflectors

varies

the

with the

ducer large

they

transducer geometry size

to the crystal

diameter

is adequate

for testing

much

smaller

size

is small.

reflector the

soundbeam

experienced Selection

in size

to actual

flat-disc

than

those

In one

traversed

produced

reflectors reflectors compared the

transthe

to detect very

ball

fairly small

areas,

transducers.

performed

diameter

use

of one-eighth

to detect

by unfocused

experiment,

a 29-mii

used

used

per-

the

discontinuities

transducers

transducers,

flat

small

reflector

may

is held from

of ultrasonic are

circular

measuretarget

a flat-topped

with

Reflectors

a flat,

Spherically-focused

sotmdbeams

obtained

surface.

on the

case,

transducer

sur-

frequency.

a ball

are

flat equal

target

transducers, the

difficulty

are

ball

reflecting

results

the

balls

transducer

In this

the

of the

effective

of the

provided

Best

example,

steel

diameter

of the

flat

and lens.

about

of the

influence

is used,

of each or

size

distort

precision

recording.

testing.

normal

For

undue

seriously

The

wavelength

profile

eliminate

measured,

imperfections.

Laboratories,

while

cases,

diameter

as possible,

to detect.

proportion,

by the

from

In

AEC

a fine-line

Hanford ball-

pen.

7.

PULSER test

quency

requires of the

pulse

a pulse

resonant

the

short

the

damping

not drive

as short

of the

pulse

For

(A microsecond

To analyze

characteristics,

the

crystal

as possible,

crystal. pulse

capability.

analysis

duration

abnormal less

than

second

and

This

one period

of high-frequency

fre-

is excited

oscillation.

is 0. 025 microseconds

is one-millionth

natural

the transducer

into much

the

of the

(5 to 25 Mc) with

a rise

a nanosecond

natural trans-

time

of 10

is one-billionth

)

8.

WIDEBAND

To prevent

the

RF amplifier 60 Mc,

rise

RECEIVER received

is used. time

DISPLAY

An effective without

and

recommended

nanoseconds. second.

with

thaf_ will

duration

frequency

ducers,

9.

a pulser

transducer

a voltage

demands

6-6

for

surface

in that

the

beam

produce

Type

amplitude

is expected

crystal

with

post

and larger

in diameter

to the

in holding

This

signal

The

one-quarter

analyzing

can

transducers.

as possible. than

target

In most

focused

distortion

When

a bad

information.

to less

frequency

adequate

chosen,

calibrating as small

is held

beam.

pendicular

carefully

invalid

when

prevent

not offer

point

are

is maintained

face

with

TARGETS

L vertical

from

becoming

A recommended

response

distorted,

receiver

of I0 nanoseconds,

a receiver

is one and

with

a gain

with

a bandwidth

of about

a wideband of 1.5

to

40 db.

SYSTEM

system

distortion.

signal

has

sufficient

A recommended amplifier

plug-in.

bandwidth

and

oscilloscope Bandwidth

rise

time

is the

to present

Tektronix

is dc to 30 Mc with

the Type a rise

information 547 with time

a

capability

of 0.010

microsecond.

expansion

features

that

are

This

desirable

scope for

combination

recording

offers

transducer

delay beam

and time

base

profiles.

J

604

RE_ORDING

i.

BEAM

PROFILES

GENERAL

Transducer

data

graphic

are

prepared,

and recording

various

2.

sheets

records

scribe

! !

OF TRANSDUCER

methods

FLAT-DISC

as shown

of transducer

used

to obtain

in Figure

analysis.

transducer

The

beam

TRANSDUCER

MEASUREMENTS

shows

a beam

plot

in water

over

6-3,

for

mounting

following

of photo-

paragraphs

de-

profiles.

i Figure

6-4

positioned been lel

cut

and

polished

while

the

transducer

These

four-beam

signal

waveform

provide

a reflector

fiat.

The

scans

amplitude taken

a permanent

3.

profile

FOCUSED

of responses made

flat

end

over

the

profiles,

from record

picked

from

the

of the

drill

reflector

taken

end

with

the

a moving

transducer,

of individual

transducer

of a metal

and the

along

a stationary

TRANSDUCER

butt

up by a fiat-disc crystal four

drill

face

parallel

has

held

paral-

paths plus

recorded

which

are

transducer,

are

transducer

shown. a return

on a photograph

to

characteristics.

MEASUREMENTS

Figure 6-5 shows the basic transducer

measurements

for a focused transducer.

With

the reflector stationary, a waveform is obtained and two beam amplitude profile plots are taken with the transducer traversed in the X-axis and the Y-axis. If the depth of field for a focused transducer is required, the beam

profile may

be taken at points

inside and outside the focal point. 4.

CYLINDRICALLY-FOCUSED

A wedge-shaped duced

soundbeam,

by the

is used

for

reflector

TRANSDUCER focused

cylindrically-focused measuring

across

beam

the

transducer width

length

in width

of the

MEASUREMENTS

and

which

by traversing beam

unfocused the

as shown

Since

beam

traversing the

signal

ball,

levels

width along

and

for

wire

length,

lens.

A steel

transducer 6-6.

over

Correct

radii of the transducer as possible which will

is pro-

ball

ball the

diameter

being tested. still produce

profiling.

is usually the

the

a concave

immersed

in Figure

depends on the frequency, crystal size, and lens A rule of thumb is to select as small a reflector adequate

has

along

beam

diameter

selection,

i.e.,

frequency,

Two

amplitude

profiles

and then

translating

narrow, length,

the may

depends

problem be avoided

on the

crystal

of maintaining

size,

same

by substituting factors

and lens

ball

that

alignment

a piece determine

while

of wire ball

for

diameter

radii.

|

the

beam wire,

are

produced

across

the

by translating beam

width

along over

the

the ball

beam

length

over

reflector.

6-7

TRANSDUCER

FREQUENCY

SERIAL

DAMPING

FACTOR,

ACOUSTICAL

BEAM

WIDTH/DIAMETER,

NO-,,.,

FOCAL

LENGTH,

FOCUSED

15 MC

FREQUENCY

LITHIUM

CRYSTAL

SULFATE

HOUSING

STYLE

CRYSTAL

SIZE.

SYMMETRY

3/16 1/4

LENS

RAD.

INSPECTOR

USED:

A.;

0.039

DIA.

STEEL

BALL

DRIVER

B.

0.039

DIA.

STEEL

BALL

DURATION,

o. 065

C.

0.039

DIA.

STEEL

BALL

AMPLITUDE

15o

CONNECTING

BEAM

DATE

TYPE

REFLECTORS

ANALYSIS

PULSE:

,MICROSECONDS VOLTS

CABLES: TYPE

LENGTH

DRIVER PULSER

TO CRYSTAL

RECEIVER

TO SCOPE

,

5'

RO 62

5'

RG 62

TIME

PULSE:

RECEIVED

A

,_

MEASURED TRACE

TRACE A.

SIGNAL TRACE DBDOWN

17'__._._SMCS

FREQUENCY A

(WAVEFORM)

2. o

B.

-'

MICROSEC/CM

.1

FOCAL

V

VOLTS/CM

LENGTH

20

0.558

INCHES

MICROSEC WATER PATH (ROUND TRIP TIME)

(Y DIRECTION) 2

/.\-

MICROSEC/cM

•5

VOLTS/CM

• 004

INCH/DIV

BEAM

..... /_\

WIDTH

-)

OR DIA..

INCHES TRACE

C.

3.0

DAMPING FACTOR TRACE A

3DB

0.007 AMP.

POINTS

B

(X DIRECTION) BEAM 2 •5

• 004

SYMMETRY:

MICROSEC/CM VOLTS

'CM

INCH/'DIV

AF:

.......

_//\

'/
18o.-36o.

i --_

TRACE TRACE

B C

COURTESY AUTOMATION INDUSTRIES,INC. Figure

6-3.

Typical

Transducer

Data

Sheet

PI BEAM

PROFILES

BEAM PROFILES

RETURN SIGNAL WAVEFORM

REFLECT(

FLAT-DISC CRYSTAL

PATH

Figure

6-4.

Fiat-Disc

Transducer

Measurements

BALL REFLECTOR

RETURN SIGNAL WAVEFORM

X-BEAM

PROFILE

FOCUSED TRANSDUCER Y-BIEAM PROFILES

Figure

6-5.

Focused

Transducer

Measurements 6-9

RETURN SIGNAL WAVEFORM

BALL REFLECTOR P_ATH WIDTH PROFILE

REFLECTOR

PATH

I

Figure

The

point

6-6.

selected

measurement

for

at the

area,

the

beam

is required,

the

(by moving

and beyond

the

i.

GENERAL

In the

following

are

focal

2.

beam

profile

the

transducer,

is taken

is determined With

If the

depth with

actually)

Measurements

the

ball

of field

for the

the

reflector

which

are

by the

stationary focused

moved nearer

beam-length in this area

of the

to points

than

beam

the

in the

focal

point

point.

each

DATA

each

of the

transducer

main

headings

tested,

the

on the

waveform

transducer

and beam

data profile

sheet plots

are

as follows.

highest

amplitude

portion

return signal waveform This record is calibrated scale,

permitting

3.

of the

beam,

as determined

is recorded photographically in millivolts on the vertical

a determination

of crystal

by the profile

shots,

the

with the transducer stationary. scale and time on the horizontal

frequency,

damping

factor,

and

sensitivity.

FREQUENCY

in this test, the actual the desigu frequency. in the water

material,

6-10

measurement amplitude.

recorded.

paragraphs, For

Transducer

PROFILE

WAVEFORM

At the

wave

beam-width of highest

OF TRANSDUCER

discussed.

analyzed

the

is also

soundbeam

ANALYSIS

Cylindrically-Focused

point

waveform

605

LENGTH

this

frequency The actual

medium.

is the

frequency

of transducer operation frequency measurement

As this that

is the frequency is recorded.

is measured is a measure

of the To record

and compared to of the acoustic

energy

used

the

acoustical

when

testing

frequency

of

the

transducer,

Figure

the

6-3

base) 4.

illustrates number

DAMPING

FACTOR

of crystal

damping

number

of positive in amplitude.

to return

to a quiescent

is measured cycles

within

the

A in Figure

factor

that state

after

reacting transducer

the

damping

arriving

unit

RF pulse

very

of time

that

this of the

reflected

the better

close

together

of the

transducer

which

than

the number

first

half method

the

crystal

of cycles

a measure related

ability

(time-

as the

This for

pulse, the

the

required

is directly

in a given

period

is defined

measurement. time

A in

frequency.

greater

By counting to resolve

factor,

are

Trace

if the

equal

factor

indicates

to the

is analyzed.

be calculated

damping

excitation.

when

smaller

per

6-3

target

may

is a measurement

of the

The

the bail

by the

ability

two signals

of damping to the

of the

damping

transducer

to re-

time.

SENSITIVITY

Sensitivity energy

refers

to the

reflected

for

from

sensitivity,

reflector

defects

ducers,

the

a flat,

ability

a relatively vary

is small,

actual

with

circular

steel

balls

diameter, also

used

units

are

culties

from

the

have

been

for

to the

a small bali.

is calibrated duration known

of the and

FOCAL

wire per

width

known, with

the

ball

be laid

of the

in size

from

the

pulse

equal

0.030

as

the

Beam

to 0.050 tiny

inch balls

in are

transducers.

These

beam

If diffi-

length.

beam

path

length

direction,

as a substitute

With

the

for

A of Figure amplitude

of the wideband

is recorded

to

are much small. The

shc_ccn in trace

sensitivity. factor

in size trans-

These

in the

lengthwise

received,

of sensitivity

to the

along

in a the

is adequate.

units.

traversing

used,

straight-beam

diameter

focused

amplification

measure

respect

along

signal

the

crystal

unfocused while

to measure

plus

or roughly flat,

of sound

In general,

small discontinuities, The reflector is also

testing

and

the

reflectors

of cylindrically-focused

dimension

may

the

amount

and lens.

For

ranging

for

centimeter

constant, down

pens,

ultrasonic

measured,

to detect.

successfully

amplitude

pulse

held

or in decibels

focal

of ballpoint

in aligning

in volts

size

the minute

crystal

to detect very transducers.

the beam

fine

vertical

beam

of one-eighth

used of fiat

in the width

The

of the

is expected

used

experienced

diameter The

tips

to detect

target.

geometry

reflector

measuring

focused

are

small

the

compared transducer

sizes of focused transducers, smaller than the beam sizes

The

cycles

crystal

solve

6.

frequency

The

factor.

test

The

by the

is reached.

5.

from

signal.

Trace

a damping

signal

of complete

half

produces generated

reflected

this

is known:

Extent cycle

first

in volts

the 6-3,

and

receiver peak-to-peak

voltage.

LENGTH

length

length

at which

length

is recorded

information a maximum manually

is not photographed return by the

signal time

but is recorded

is obtained base

on focused

measurement

as the water transducers.

on the

oscilloscope

path Focal screen

6-11

betweenthe excitation pulse and the water path position at the point of maximum amplitude response. The transducer is held over the center of the ball target and moved toward or away from the ball until the maximum reflected signal is received. 7.

BEAM

The

beam

cycle

amplitude

with

the

horizontal of the

open,

The

highest

symmetry

curves

8. The

BEAM beam

calibrated soundbeam. abnormal

variations, in electrodes

6-12

next

of these

records

return

of transducer

travel.

from

curves

with

each respect

modes

which

With for

the

and

major

so on.

the

each

individual

cycle

to one

another

crystal

shutter

envelope, This

with

recording

highest

to each

is indicative The

lens

ampli-

produces other.

of uniformity

symmetry

thickness,

the

is pro-

of recording respect

the

motion

delays

of the next

half

and

The

cycle

the

system

signal

in turn

individual

of the transducer.

in damping,

of each

of transducer

screen.

curve,

envelopes

of these

thickness,

or

components.

AND SYMMETRY

is read

horizontal

directly

axis,

And through conditions centering bonding

from

or at the

is recognized

and

amplitude

potentiometer

recording

cycle

send-receive

WIDTH

lens

a data

oscilloscope

lower

by variations

width

in millivolts drives

curves

transducer

Non-symmetry and

amplitude

in the

of the

the

show

or centimeters,

target

across

the

is affected

bonding

the

response

of operation

calibrated

a distance/amplitude

records

superimposed

photographs

in mils,

across

held cycle

The

scale

RF signal

duced.

on the

calibrated

transducer

camera

PROFILES

profiles

vertical

scale

composite

tude

AMPLITUDE

the width 3-db

as variations critical

analysis

can be identified.

down

also

been

profile

points

on each

in the

profile

of these Porosity linked

envelope side

patterns

beam

Non-symmetry

or misalignment. have

of the

envelope may

in lenses

to distortion

displayed

of the of the

profile

variations, and

peak.

propagated

be caused

in beam

on the

normal by backing

small profiles.

imperfections

kM

CHAPTER

7:

COMPARISON

AND

TABLE

SELECTION

OF

OF

NDT

PROCESSES

CONTENTS Page

Paragraph 700

GENERAL

701

METHOD

7O2

NDT

7O3

DISCONTINUITY

CATEGORIES

7O4

DISCONTINUITY

CHARACTERISTICS

ANA

..................................... IDENTIFICATION

DISCONTINUITY

LYSIS

7-3

......................... SELECTION

7-3

.....................

7-3

........................ AND

7-3 METALLURGICAL

.....................................

METHODS

7- 6

705

NDT

APPLICATION

AND

LIMITATIONS

..........

7-6

706

BURST

707

COLD

708

FILLET

709

GRINDING

710

CONVOLUTION

711

HEAT-AFFECTED

712

HEAT

713

SURFACE

714

THREAD

715

TUBING

716

HYDROGEN

FLAKE

717

HYDROGEN

EMBRITTLEMENT

718

INCLUSIONS

719

INCLUSIONS

720

LACK

721

LAMINATIONS

722

LAPS

AND

SEAMS

...............................

7-40

723

LAPS

AND

SEAMS

...............................

7-42

724

MICRO-SHRINKAGE

...............................

7-44

725

GAS

726

UNFUSED

727

STRESS

728

HYDRAULIC

729

MANDREL

730

SEMICONDUCTORS

731

HOT

732

INTERGRANULAR

........................................ SHUTS

7-8

....................................

CRACKS

(BOLTS)

CRACKS

..........................

7-10

...............................

CRACKS

CRACKS

SHRINK

CRACKING

_ ...................

.............................

CRACKS

CRACKS

7-14

............................

ZONE

TREAT

7-10

.........................

................................

CRACKS

(rNCONEL

"X")

......................

............................... .......................

CORROSION

DRAG

TEARS

7-36

7-46

..............................

7-48 7-50

..............................

.................................

7-52 7-54

...............................

7-56

.................................... CORROSION

7-30

7-38

...............................

TUBING

7-26

7-34 ..........................

..................................

POROSITY

7-22

7-32

...................................

POROSITY

7-20

7-28

.................................... PENETRATION

7-18

7-24

....................................

OF

7-16

7-58 .......................

7-60

7-1 V

TABLE

OF

CONTENTS

(CONT)

Page ..........................

7-4

Particle Test .......................... Test ...............................

7-4

Figure

7-1

Liquid

Figure

7-2

Figure

7-3

Magnetic Ultrasonic

Figure

7-4

Eddy

Figure

7-5

Figure

7-6

Radiographic Test Burst Discontinuities

Figure

7-7

Cold

Figure

7-8

Fillet

Figure

7-9

Grinding

Figure

7-10

Convolution

Figure

7-11

Heat-Affected

Figure

7-12

Heat

Figure

7-13

Surface

Shrink

Figure

7-14

Thread

Crack

Discontinuity

.......................

7-25

Figure

7-15

Tubing

Crack

Discontinuity

.......................

7-27

Figure

7-16

Hydrogen

Flake

Figure

7-17

Hydrogen

Embrittlement

Figure

7-18

Weldment

Inclusion

Figure

7-19

Wrought

Figure

7-20

Figure

7-21

Lack of Penetration Discontinuity ................... Lamination Discontinuity .........................

Figure

7-22

Laps

and

Seams

Discontinuity

in Rolled

Figure

7-23

Laps

and

Seams

Discontinuity

in Wrought

Figure

7-24

Micro-Shrinkage

Figure

7-25

Gas

Figure

7-26

Unfused

Figure

7-27

Stress

Figure

7-28

Hydraulic

Figure

7-29

Mandrel

Figure

7-30

Semiconductor

Figure

7-31

Hot

Figure

7-32

Intergranular

7-2

Penetrant

Current

Shuts

Test

Test

.............................

7-6

............................. ...........................

7-6

Discontinuity

Crack

Treat

Cracking

Cracks

Porosity

Discontinuity

Discontinuity

7-21 7-23

7-29

......................

Discontinuity.

Discontinuity

7-19

.............

..................

Discontinuity

Discontinuity

7-17

....................

Discontinuity

Discontinuity

Inclusion

7-15

...................

Discontinuity

Crack

7-13

......................

Discontinuity

Zone

7-11

........................

Discontinuity

Cracks

7-9

.........................

Discontinuity

Crack

7-4

7-31

................

7-33

...................

7-35

....................

Threads Material

.....................

7-37 7-39 ......... ........

7-41 7-43 7-45 7-47

........................

Porosity

Discontinuity

.....................

7-49

Corrosion

Discontinuity

.....................

7-51

Discontinuity

.....................

7-53

Tear

Tubing Drag

Discontinuity Dis continuity

Discontinuity Corrosion

7-55

....................... ......................

7-59

.......................... Discontinuity

7-57

................

7-61

CHAPTER

700

7: COMPARISON

AND

SELECTION

OF

NDT

PROCESSES

GENERAL

The

purpose

of this

discontinuities,

chapter

is to summarize

and to list

the

NDT

the

methods

characteristics

which

may

of various

be employed

types

to detect

of

each

type

of discontinuity. The

relationship

when

applied

as type (heat

between to the

the

detection

of discontinuity

treating,

various

NDT

of a specific

(inherent,

machining,

METHOD

will

or service),

and the

and their

discontinuity

process,

or plating),

processing) all will help determine one test method over another. 701

methods

and

be shown.

and the

variables

processes

(metallurgical,

of testing

limitations

Such

manufacturing

limitations

sequence

capabilities

structural, ultimate

or

selection

of

IDENTIFICATION

Figures 7-1 through 7-5 illustratefive NDT methods. Each illustrationshows the three elements involved in all five tests, the differentmethods in each test category, and tasks that may 702

NDT

The

be accomplished

DISCONTINUITY

discontinuities

part

of the

space

that

many

industry.

only

a few

ent

conditions

During

Each

of the

specific

specific

1.

of the

discontinuities

the

various

of discontinuities which

configuration,

would

for

products

inclusion

not be radically

standards,

732 are

of the tn this

changed

and environment

only

aero-

section,

under

were

a

differ-

chosen.

CATEGORIES

and

are

service.

divided

Each and

into

of these

is associated

configuration,

are There

Wrought. which

with

706 through

with

the

three

general

categories ferrous

categories:

is further

classified

or nonferrous

manufacturing

processes

materials, if applicable.

DISCONTINUITIES

molten:metal. a.

in paragraphs

associated

selection

the discontinuity material

INHERENT

Inherent

the

are

discontinuities

processing,

to whether

the

be reviewed

that

of design,

DISCONTINUITY

as

will

discontinuities

703

inherent,

SELECTION

hundreds

of those

with a specific method.

are

Inherent related

those are

discontinuities

that

are

related

to the

solidification

two types. wrought

to the

discontinuities

melting

and

original

cover

those

solidification

discontinuities of the metal

or ingot.

_-

7-3

ELEMENT

TASK

PROCEDURE

VISIBLE DYE PENETRATE TESTING

PERSONNEL

DETECT SURFACE DISCONTINUITIES

TECHNIQUES_-'-

SPECIALIZED APPLICATIONS

FLUORESCENT PENETRANT TESTING

I EQUIPMENT _--

Figure

7-1.

ELEMENT

Liquid

Penetrant

Test

TASK

PROCEDURE

TESTING DRY VISIBLE

LOCATE DISCONTINUITY

I PERSONNEL_

TEC.NIQUESI I

TESTING WET VISIBLE SPECIALIZED APPLICATIONS

I EQUIPMENT

TESTING __WET FLUORESCENT

Figure

7-2.

ELEMENT

Magnetic

Particle

Test

PROCEDURE

TASK LOCATE DISCONTINUITY

PERSONNEL_-

DETERMINE BOND

TESTING

TECHNIQUES I MEASURE THICKNESS

SPECIALIZED APPLICATIONS

EQUIPMENT ]-_

I V

Figure 7-4

7-3.

Ultrasonic

Test

PROCEDURE

TASK

MANUAL CONDUCTIVITY TESTING

CONDUCTIVITY MEASURE

I

HARDNESS DETERMINE

I

ELEMENT

---I

i

MANUAL DISCONTINUITY

PERSONNELI-'_

TESTING

DETECT DISCONTINUITIES

MANUAL COATING AND PLATING THICKNESS TESTING

TECHNIQUES

MEASURE PLATING THICKNESS

MANUAL OR AUTOMATIC PHASE ANALYSIS TESTING DIMENSIONAL DETECT CHANGES

I

APPLICATIONS SPECIALIZED

I

EQUIPMENTI-----

AUTOMATIC MODULATION ANALYSIS TESTING

Figure

7-4.

Eddy

Current

Test

C ELEMENT

PROCEDURE

PERSONNEL

TASK OBSERVE FUNCTION

m

TESTING FILMLESS

__

DISCONTINUITY LOCATE TECHNIQUES

I

__

J

X-RAY FILM

"I

TESTING

DETERMINE BOND

TESTING GAMMA RAY FILM

Figure

7-5.

I

Radiographic

APPLICATIONS SPECIALIZED

I

Test

7-5

b.

Cast.

Inherent

related

to the melting,

includes

those

variables

discontinuities

heat

and plating.

SERVICE

discontinuities

service

conditions

such

cover such

those

will

are

article.

It

to manufacturing

excessively

high pouring

and stacking.

discontinuities

that are

forming,

actual

discontinuities corrosion,

related

extruding,

to the various rolling,

related

welding,

to the various

and errosion.

AND METALLURGICAL

encompasses

photos

that are fatigue,

CHARACTERISTICS

characteristics

and reference cussion

which

of the cast

be inherent

gating,

handling,

as machining,

as stress

DISCONTINUITY

Discontinuity

discontinuities

DISCONTINUITIES

Service

704

would

feeding,

gases,

are those

processes

3.

those

and solidification that

as inadequate entrapped

manufacturing treating,

casting,

are

DISCONTINUITIES

PROCESSING

Processing

discontinuities

discontinuities

such

temperature, 2.

cast

an analysis

that illustrate

examples

ANALYSIS

of the specific

discontinuity

of the discontinuity.

The dis-

cover:

a.

Origin and location of discontinuity (surface, near surface, or internal).

b.

Orientation

(parallel

c.

Shape

(flat,

irregularly

d.

Photo

(micrograph

Metallurgical

e.

or normal

to the grain).

shaped,

and/or

analysis

or spiral).

typical

overall

view

(how the discontinuity

of the

discontinuity).

is produced

and at what

stage

of manufacture). 705 I. The the may

NDT

METHODS

APPLICATION

LIMITATIONS

GENERAL technological level

accomplishments

of test

reliability

now selectively

zone

application

of the

the

Ioading

characteristics

end

reliability

otherwise

7-6

AND

would

and the

end product

of the have

in the field reproducibility

specific

of the

article.

product,

but

been

acceptable.

to a point

article.

and takes it does

of nondestructive

into

This

where

zoning

consideration Such

reduce

an evaluation needless

testing the

design

is based

upon

the

environment in no way

rejection

have

brought

engineer the

structural

as well reduces

of material

the that

as

b

Just

as the

size

will

a die

structural

vary

forging

that

not require zoned

for

the rigid

The

nondestructive

control

design

produce

kept

the

in mind

methods over

NDT

another

Material

c.

Accessibility

d.

Level

e.

Equipment

f.

Cost

order and

new

3. The

assume

would

can be

zoned

for

discontinuities.

method

which

that

NDT

all

will

satisfy

methods

can

of discontinuity.

evaluation

may

of a specific

supplement the

variabies

each

same

such

discontinuity

other

task.

and

The

that

it should

several

selection

be

NDT

of one

method

as:

processes

of article desired

available

for

knowledge each

listed

for

for

chapter

that

in paragraphs

in mind

order

a planned

that

of test

analysts

of the

testing.

discontinuity.

be kept the

variables,

NDT

discontinuity

particular

alter

above

requiring

each

it should may

of the

article

706 through

However,

when

rapidly

developing

the

732 are

in

reviewing

that

NDT

field

preference.

LIMITATIONS limitations the

NDT

applicable but

For

also

be applicable

rial

or

and

in many

these

associated made

and

the cases

reasons,

various the

capability

with

a specific

aware

of the

the

structural

are

under many

discontinuity. factors

will

of the

listed

for

slightly

intent

influence

with test

different

conditions

of environment,

of this

applicable affect

ai'ticle

discontinuity

all

the

the

not only

one

combinations mentioning

The that

vary

Limitations

reliability

that

do not permit

many

methods

environment.

discontinuities

In addition,

test

NDT

service

limitations

to other

environment.

material,

to the

material,

test,

affected.

are

type

and

larger

the

sections

forging

higher,

example,

of discontinuity

develop

techniques

standard, the

the

of acceptability

methods

are

For

web

The

permit

and not

same

thin

forging.

select

discontinuity

METHOD

manufacturing

be made

of the

article

of performing

origin

of preference

portion

methods upon

and

To satisfactorily

NDT

for

is based

b.

The

method

NDT

Type

must

NDT

be capable

a.

task

THE

also

allowable

configuration.

extremely

whole

requirements

the

the

and

applications

must

specific

varies,

and the

structural

structural

for

article

for

specialist

of the

that

may

the

OF

the

of manufacture

of material

the

reliability

SELECTION

In selecting

masses

testing

same

method

of acceptance

where

where

objective the

2.

large level

control

rigid

within

on the

has

same

less

the

application

depending

is may of matelocation,

limitations

that

chapter

is fulfilled

selection

of a valid

may

be if you

NDT test.

7-7

_.L.-q

706

BURST

1.

CATEGORY.

Processing

2.

MATERIAL.

Ferrous

3.

DISCONTINUITY

Surface

or

faces

or very required

4.

Straight

tight.

Forging

D

bursts during

Bursts

are

d_

in size

Found

or internal

with

used

Bursts

are

material

Ultrasonic

testing

article

the

extruding

seldom

attributed

operation.

and, therefore, center.

healed

during

is distinguishable

subsequent

breaks

of internal

in the

material

and

on the

scope.

reflection

of detecting

by other

NDT

areas,

tool

raised

produce

MAGNETIC

PARTICLE

(1)

Usually internal

used on wrought burst.

(2)

Results

are

tested, cleaning

penetrant

working.

bursts. they

varying

resemble

of burst

material,

gas

tears,

foreign

ultrasonic

test

to surface

material

and

near

METHOD.

is to be applied

all traces of dye penetrant in applicable solvent.

bubbles

results. Testing diameter.

is

METHOD

ferrous

TESTING

which

methods.

adverse

TESTING

a crack,

degrees

EDDY CURRENT TESTING METHOD. Not normally used. restricted to wire, rod, and other articles under 0. 250 inch

PENETRANT

move-

V

is capable

limited

to

or metal

L_

detection

sharp

may

are

working

AND LIMITATIONS

not be detected gouges,

which

METHOD

definite a very

fluorescent

inter-

7-6.)

or excessive

or

and very

for

producing

LIQUID

large

in wrought

Figure

ruptures

temperature,

APPLICATION

Normally

on the

grain. (See

rolling,

large

(1)

Nicks,

the

varying

not have a spongy appearance even if it should occur at the

TESTING

could

C_

surface

ULTRASONIC

(4)

with

forging,

often

METHODS

(3)

b.

are the

c.

(2)

cavities

or extruding.

at an incorrect

A burst does from a pipe,

a.

Material

ANALYSIS

b.

NDT

parallel

rolling,

processing ment

or irregular

Usually

forging,

METALLURGICAL a.

Wrought

CHARACTERISTICS

internal.

which

and Nonferrous

that

surface

surface

first

or exposed

evaluation.

Not normally

to an article should

has

previously

be removed

used.

When

dye penetrant by prolonged

So

RADIOGRAPHIC as the size,

TESTING

direction

of the burst,

and material

thickness

A

FORGING EXTERNAL

C

ROLLED BAR INTERNAL

METHOD. close restrict

Not normally interfaces, the

capability

BURST

B

D

BURST

Figure

7-6.

Burst

used.

wrought

Such

variables

material,

discontinuity

of radiography.

BOLT INTERNAL BURST

FORGED BAR INTERNAL

BURST

Discontinuities 7-9

707

C OLD

SHUTS

1.

CATEGORY.

Inherent

2.

MATERIAL.

Ferrous

3.

DISCONTINUITY

v,j

and Nonferrous

Cold

METALLURGIC shuts

surging,

are

produced

during

prevent

a fusion

prevalent NDT a.

where

two

LIQUID

(2)

(4)

(5)

meet

formed

appear

Liquid

surface

resembling

InconeI

"X,"

Certain

castings

may

removal

of the

excessive

Geometric

Rene

of wet

coming

from

different

metal

flQws

over

or any

factor

that

shuts.

several

splashing,

They

sprues

are

it,

the

will

more

or gates.

cold

shuts

in both

ferrous

and nonv

regular, cross

have

continuous, section

testing

41) should

not

surfaces

thereby

of nickel

may

area

may

indication,

in which alloys

percent

it occurs.

(such

as

sulfur.

be blind

and

from

which

be difficult.

orifices, masking

intermittent

base

0.5

which

(recesses,

or

of the

exceed

penetrants

developer

cold

with

from

LIMITATIONS

for the

configuration

result

other

metal,

produce

surface

to the used

may

METHOD.

as a smooth,

penetrant

buildup

cast

of metal the

sluggish

will

TESTING

parallel

streams

in a mold AND

They

before

on cold,

used to evaluate materials.

reasonably (3)

are

PENETRANT

Will

surface

films

APPLICATION

Normally ferrous

on the

metal.

of two

of one

surfaces

which

METHODS

indentations

molten

or meeting

surface

in castings

(1)

casting

solidification

of interposing

smooth

ANALYSIS

pouring,

Also,

presence

.

AL

interrupted

directions.

Material

CHARACTERISTICS

Surface and subsurface. Generally a forging lap. (See Figure 7-7.) 4.

Cast

and flanges) any detection

may

permit

of a dis-

continuity. be

MAGNETIC

PARTICLE

(1)

Normally

(2)

The

used

TESTING

for

metallurgical

some

cases

not result

the

cations

arise

portion

exhibits

screening

nature

magnetic from

testing

or other

a duplex

strong

of ferrous

materials.

of 431 corrosion-resistant

particle

a crack from

METHOD

magnetic

Indications

harmful

structure

steel are

obtained

discontinuities. within

retentivity

the and

other

that

which

These

material, the

is such

do

indi-

wherein does

in

one

not.

V 7-I0

e.

RADIOGRAPHIC

TESTING

(1)

Normally continuities.

(2)

Appear definite

(3)

Casting

detectable

a distinct dark smooth outline. configuration

line

may

while

or band

have

testing

of variable

inaccessible

for

other

length

areas

casting

dis-

and width,

which

can

and

only be

by radiography.

ULTRASONIC article

by radiography

as

detected d.

METHOD

TESTING

configuration

METHOD.

do not

Not

recommended.

as a general

rule

METHOD.

Not

lend

Cast

themselves

structure

and

to ultrasonic

testing. e.

EDDY

CURRENT

figuration

and

TESTING

inherent

material

A

B

INTERNAL

COLD

Figure

variables

SURFACE

COLD

SHUT

7-7.

restrict

Shuts

Article

the

use

COLD

SHUT

of this

conmethod.

SHUT

C

Cold

recommended.

SURFACE

MICROGRAPH

Discontinuity 7-11

708

FILLET

CRACKS

(BOLTS)

1.

CATEGORY.

Service

2.

MATERIAL.

Ferrous

3.

DISCONTINUITY

Surface.

Located

inward. 4.

(See

cracks

this

bolt

Figure

due

failure,

failure,

which

.

NDT a.

where

where

to the

stress

operation

starting

at the

is surface

change

shank

of the point

of the bolt

and

progressing

TESTING

Used

(2)

A wide selection of transducers evaluation for fillet crack.

(3)

Being

a definite

sharp

reflection.

application Ioad

These

tensile

risers

are

built

at the

surface

and

propagates

of

fluctuates

loads

can

in.

cause

Fatigue inward.

LIMITATIONS

for

service

break

associated

discontinuities

and

equipment

in the material,

(Actual

the

propagation

of this

enable

scope

on the

pattern

type. spot

V

will be a very

can be monitored

by using

)

Ultrasonic

equipment

be used

(1)

Normally

(2)

May be used

has

to give

PENETRANT used

confined

the

tensile

the

METHOD

(1)

should

the

as between

stress

the

AND

such

During

whereby

mechanism. starts

occurs,

created.

place,

where

APPLICATION

extensively

are

takes

phenomenon,

ULTRASONIC

LIQUID

with the

in diameter

risers

loading

ultrasonics.

b.

of the fillet

a marked

repeated

METHODS

(4)

Material

ANALYSIS

Junction

fatigue

Wrought

7-8.)

in service

in magnitude

Nonferrous

at the Junction

occur

head-to-shank

and

CHARACTERISTICS

METALLURGICAL

Fillet

kJ

extreme

TESTING during

for both

sensitivity,

reproducible

and

established

standards

results.

METHOD

in-service ferrous

and

reliable

overhaul

or troubleshooting.

and nonferrous

bolts,

although

usually

to the nonferrous.

(3)

Will

appear

(4)

Structural to paint

as a sharp damage

strippers,

clear

may

indication.

result

alkaline

from coating

exposure removers,

of high

strength

deoxidizer

steels solutions,

etc. (5)

Entrapment areas

may

under cause

fasteners, corrosion

in holes, due

to the

under penetrant's

splices,

and

affinity

in similar for

moisture.

V 7-12

c.

MAGNETIC

(2)

Will

(3)

Sharp

(4)

17.7 pH is only slightly magnetic becomes strongly magnetic after

fillet this e.

appear fillet

areas

particle

cracks.

cracks.

evaluate

bolts.

sharp

may

indication

produce

with

a heavy

non-relevant

buildup.

magnetic

in the annealed heat treatment,

indications.

condition, but when it may be mag-

tested. TESTING

Other

NDT

METHOD. methods

Not normally

are

more

used

compatible

for detection to the

of

detection

of

of discontinuity.

RADIOGRAPHIC fillet

as clear

CURRENT

type

on ferrous

METHOD

Normally

EDDY

used

TESTING

(1)

netic d.

PARTICLE

TESTING Surface

due to size

METHOD.

Not normally

discontinuities of crack

of this

in relation

to the

type

used

would

thickness

for detection

be difficult

of

to

of material.

C

A

B

%.J

FRACTURE AREA OF(A) POINT OF FAILURE

SHOWING

Figure

FILLET

TANGENCY

7-8.

Fillet

FATIGUE

FAILURE

C

Crack

CROSS-SECTIONAL FILLET SHOWING

AREA OF FATIGUE CRACK TANGENCY POINT IN RADIUS

iN

Discontinuity 7-13

709

GRINDING

CRACKS

k.J 1.

CATEGORY.

Processing

2.

MATERIAL.

Ferrous

3.

DISCONTINUITY

Surface.

Very

but not always, direction case Figure 4.

shallow

and

occur and

They

at the

root.

Grinding

are

ceramic

found

Similar

cracks

in highly

materials

METALLURGICAL

that

heat

are

to heat

are

treat

generally

treated

subjected

cracks

at right

articles,

and usually, angles

to the

chrome

to grinding

plated,

operations.

(See

ANALYSIS

of hardened

caused

usually

by local

caused

rapid

feed,

6.

NDT a.

surfaces

frequently

overheating

of the

by lack

of or poor

or too heavy METHODS LIQUID (1)

(2)

Normally

(4)

b.

penetrant

The

thermal

cracks

overheating

ground

is

wheel,

too

pattern are

longest

penetration

Articles

the

that

the

discontinuity to the

most

and

materials

for

the

detec-

appear

as irregular,

checked,

or

lines. discontinuity

degreased

should

application

TESTING

(2)

Grinding

cracks

although

in extreme

in which

case

to indicate

and require

the

still

have

sufficient

solvent time

entrapped for

evaporation

penetrant. METHOD

materials.

are they

may

be allowed

of the

to ferrous

generally cases may

sensitivity depth

will

difficult

been

Restricted

as its

and nonferrous

time.

PARTICLE

Magnetic

ferrous

of fine

have

prior

METHOD

indication

Cracks

and

These

ground.

cracks.

(1)

(3)

cracks.

AND LIMITATIONS

on both

of grinding

MAGNETIC

being

a dull or improperly

TESTING

used

shattered (3)

coolant,

APPLICATION

Liquid

introduces surface

cut.

PENETRANT

tion

7-14

sharp

in groups.

7-9. )

Grinding are

CHARACTERISTICS

of grinding.

hardened

and Nonferrous

below

at right

a complete

be parallel

decreases the

surface

angles

to grinding

network

of cracks

to the

as the

size

increases.

magnetic

direction, may

appear,

field.

of grinding

crack

decreases

in

c.

EDDY

CURRENT

grinding

cracks.

developed d.

better e.

for

ULTRASONIC grinding

TESTING

Eddy current

nonferrous

TESTING

METHOD.

Other to this

RADIOGRAPHIC grinding

cracks.

methods

are

forms

type

TESTING Grinding

more

suitable

Not normally

equipment

a specific

cracks. adapted

METHOD.

has

the capability

Not normally

or NDT

are

METHOD. for

for detection

of

and can be

application.

of discontinuity

cracks

used

used

more

for detection

economical,

of

faster,

and

than ultrasonics. Not recommended

are too tight

detection

and

for detection

small.

of grinding

Other

of

NDT

cracks.

m

A

.

TYPICAL

CHECKED GRINDING CRACK PATTERN

r [

........

t

•

B GRINDING CRACK PATTERN NORMAL TO GRINDING

Figure

7-9.

Grinding

Crack

C

.

T.

MICROGRAPH OF GRINDING CRACK

Discontinuity

7-15

710

CONVOLUTION

CRACKS

I.

CATEGORY.

Processing

2.

MATERIAL.

Nonferrous

3.

DISCONTINUITY

Surface.

Range

periphery Figure 4. The

from

which

treatment.

The

Subsequent on these

a.

extend

to open

fissures.

longitudinally

Situated

in direction

on the

of rolling.

(See

ANALYSIS

peel'

effect

stretches

the

roughened

service pits

NDT

and

fractures

)

'orange

operation

micro

convolutions

METALLURGICAL rough

.

in size

of the 7-10.

CHARACTERISTICS

and

of convolution material

surface

application form

METHODS

or from contains

(vibration

fatigue

cracks

and

AND

TESTING

is the

chemical

small

pits

flexing)

as shown

APPLICATION

RADIOGRAPHIC

cracks

result attack

which may

in the

of either such

form

a forming

as pickling

stress

introduce

risers.

stresses

accompanying

that

act

photograph.

LIMITATIONS

METHOD

(1) Used extensively for this type of failure. (2) Configuration of article and location of discontinuitylimits detection almost exclusively to radiography. (3) Orientation of convolutions to X-ray

source is very criticalsince

those discontinuitieswhich are not normal

to X-ray

may not register

on the film due to the lack of difference in density. (4)

Liquid

penetrant

replace (5)

The

radiographic

type

ULTRASONIC convolution and internal

the

area

TESTING cracks. micro

particle

and ultrasonic

of marking

to identify article. b.

and magnetic

material

METHOD.

Configuration fractures are

may

supplement

but not

testing.

(e.g,,

of discontinuities

testing

grease may

pencil affect

Not normally

on titanium)

the

used

structure

for

the

of the article (double-walled all factors which restrict the

used of the

detection

of

convolutions) use of ultra-

sonics.

Co

EDDY

CURRENT

of convolution tion

does

TESTING

cracks.

not lend

itself

As

METHOD. in the

to this

case

method

Not normally of ultrasonic

used testing,

for the

the

detection

configura-

of testing.

V 7-16

d.

LIQUID detection they creates

e.

A

C

are

PENETRANT of convolution internal

and are

a serious

problem

MAGNETIC

TYPICAL

HIGHER ORANGE

TESTING cracks.

TESTING

CONVOLUTION

MAGNIFICATION

superimposed

Not recommended the discontinuities over

METHOD.

Not applicable.

B

SHOWING

PEEL

CROSS-SECTION

MICROGRAPH CRACKING

Figure

7-10.

an exterior

shell

for the are surface, which

of entrapment.

DUCTING

OF CRACK

METHOD. Although

Convolution

Cracks

Material

is nonferrous.

OF CRACKED

CONVOLUTION

OF CONVOLUTION

WITH

PARTIAL

ON SIDES

Discontinuity

7-17

711

HEAT-AFFECTED

ZONE

CRACKING

%J 1.

CATEGORY.

Processing

2.

MATERIAL.

Ferrous

3.

DISCONTINUITY

Surface. affect 4.

Often zone

quite

deep

content.

failure

and require NDT a.

and

very (See

Steels

Figure

zones

that

Usually

parallel

with

the

weld

in the

heat-

7-11.)

of weldments

contain

preheating

METHODS

tight.

ANALYSIS

of heat-affected

carbon

Nonferrous

CHARACTERISTICS

METALLURGICAL

.

and

of the weldment.

Hot cracking

(Weldments)

more

prior

PARTICLE

(I) Normally

increases 0.30%

carbon

in severity are

prone

with to this

increasing type

of

to welding.

APPLICATION

MAGNETIC

than

AND TESTING

LIMITATIONS METHOD

used for ferrous weldments.

(2) Prod burns are very detrimental, especially on highly heat treated articles. May contribute to structural failure of article. (3) Demagnetization

of highly heat treated articles can be very difficult

due to metallurgical structure. b.

LIQUID

PENETRANT

(1) Normally

TESTING

METHOD

used for nonferrous weldments.

(2) Material that has had its surface obliterated, blurred, or blended due to manufacturing processes should not be penetrant tested until the smeared surface has been removed. (3) Liquid penetrant testing after the application of certain types of chemical film coatings may

be invalid due to the covering or filling

of the discontinuities. c.

d.

RADIOGRAPHIC

TESTING

METHOD.

Not normally used for the detection

of heat-affected zone cracking.

Discontinuity orientation and surface

origin make

more

ULTRASONIC

other NDT

methods

TESTING

METHOD

(i) Used where

suitable.

specialized applications have been developed.

(2) Rigid standards and procedures

are required to develop valid tests.

(3) The configuration of the surface roughness root radii and the slope condition) are major sound beam. 7-18

(i.e. , sharp versus rounded factors in deflecting the

eo

EDDY

CURRENT

TESTING

of heat-affected detecting used

zone

nonferrous

as magnetic

METHOD.

cracking. surface

particle

Not normally

Eddy

current

discontinuities; or liquid

equipment however,

Figure

has

the

detection

capability

it is not

of

as universally

|

MICROGRAPH OF WELD AND HEAT-AFFECTED ZONE SHOWING CRACK NOTE COLD LAP WHICH MASKS THE ENTRANCE TO THE CRACK

B

;.,j

for

penetrant.

•

A

used

7-11.

MICROGRAPH OF CRACK SHOWN IN(A)

Heat-Affected

Zone

Cracking

Discontinuity

7-19

712

HEAT

TREAT

CRACKS

1.

CATEGORY.

Processing

2.

MATERIAL.

Ferrous

3.

DISCONTINUITY

Surface.

Usually

direction

on the part.

sharp to the 4.

deep

and

the

heating

heating

or cooling,

and

Where built-in develop.

MAGNETIC For

(3)

AND

materials,

particles

may

article,

been

exposed

cross-sectionaI

(keyways

or grooves}

causing

it

additional

LIMITATIONS METHOD

heat

treat

cracks

are

wilI

normally

indications

of origin fillets,

normally

detected

are

areas

or areas

that

with

would

rapid

be straight,

develop

changes

by mag-

and

steels

17.7,

431)

irrelevant

(17.4, PENETRANT

and

TESTING

For nonferrous method.

materials

of origin

may

produce

liquid

would

penetrant

be the

Materials be tested

or articles that will eventually with compatible penetrants.

(2)

Magnetic

particles

such

thickness.

treatable

stainless

indications.

as those

is the recommended

listed

above

for

testing.

TESTING

not used.

heat

testing

same

particle

Normally

risers,

or

METHOD

magnetic

(1)

stress

forked,

in material

of age hardenable

CURRENT

up by unequal

testing.

points

points

be set

of the material

structure

EDDY

can be in any thickness,

have

or unequal

strength

Metallurgical

Likely

and

of material which

stresses

occur

TESTING

Likely

LIQUID

Material

pattern

change

the tensile

risers

(3)

(2)

7-20

stress

The magnetic particles curved indications.

(1)

Cast

discontinuities 7-12. )

of the

exceed

PARTICLE

as keyways,

C.

may

(2)

(4)

and

a definite

rapid

localized

APPLICATION

ferrous

netic

b.

process movement

stresses

METHODS

follow with

nicks, and (See Figure

restricted

to rupture. cracks may

(1)

Seldom in areas

cooling

These

NDT

Wrought

ANALYSIS

thickness.

a.

forked.

Originate

machining marks, fillets, surface of the material.

During

Nonferrous

CHARACTERISTICS

METALLURGICAL

5.

and

be used

in LOX

systems

must

METHOD

and liquid

penetrant

are

more

direct

and

economical.

d.

ULTRASONIC

TESTING

treat

If used

cracks.

discontinuity. e.

METHOD. the

scope

Recommended

RADIOGRAPHIC heat

treat

NDT

methods

TESTING

cracks.

wave

will

mode

METHOD.

Surface

designed

Not normally pattern

would Not

discontinuities

for

surface

used

show

indication

more

used easily

for

detection

detected

FILLET RELIEF

B

Figure

AND MATERIAL THICKNESS RADIUS CRACKING (LOWER

H_E'AT TREAT

7-12.

CRACK

Heat

of a

of by other

application.

i A

of heat

be surface.

normally are

for detection

a definite

DUE

Treat

CRACKS LEFT)

(TOP

/

CENTER)

TO SHARP

MACHINING

MARKS

Cracks

Discontinuity 7-21

713

SURFACE

SHRINK

1.

CATEGORY.

2.

MATERIAL.

3.

DISCONTINUITY

Surface. from

Ferrous

small,

transverse 4.

Processing

Situated

very

the

CRACKS

and Nonferrous

CHARACTERISTICS

on the tight,

face and

direction

shrink

heating

or welding

stresses

that

Restriction cooling,

o

a.

generally

may

also

shrink

(2)

Liquid

penetrant

Assemblies or press

Range run

in size

parallel

or

application,

material

area

causing of the

the

either may

set

material

material

in up

to crack.

during

heating,

stresses.

METHOD

are

normally

equipment for

which

heat

in a localized

AND LIMITATIONS

cracks

fittings

of improper

or expansion)

TESTING

will

and mask

detected

is easily

joined retain the

and

and

during

weldments.

riveting,

the penetrant,

penetrant.

can be used

nonferrous

by bolting,

adjoining

by liquid

portable

both ferrous

are

PARTICLE

intermittent

which

will

seep

welding, out after

surfaces.

in a hot air dryer should be avoided

TESTING

(1)

Ferrous

(2)

Surface

discontinuities

produce field.

indications

weIdments

Areas

of grease

might

be damaged

solids

7-22

metal. may

or by similar means, to prevent evaporation

excesof

penetrant.

MAGNETIC

(3)

Cracks

7-13.)

of the

When articles are dried sive drying temperature the

and base

deep.

or cooling

up excessive

control

developing

b.

set

PENETRANT

in-process

result

strength

APPLICATION

Surface

(4)

the

(contraction

(1)

(3)

zone,

and

Figure

Heating

the tensile

METHODS LIQUID

fusion

to open (See

article.

movement

or welding NDT

are

of the

exceed

weld,

ANALYSIS

cracks

of the

of the shalIow,

of welding.

METALLURGICAL

Surface

(Welding)

should

are

normally that

since

fittings,

METHOD

are they

be masked

before

by magnetic

parallel do not

bearing

or clogged

tested

to the interrupt

races,

by the

testing.

magnetic or distort

or other

suspension

particle

similar solution

method.

field the

will

not

magnetic

items

that

or magnetic

c.

L,

EDDY

CURRENT

(1)

Normally

(2)

Probe

TESTING

confined

METHOD

to nonferrous

or encircling

coil

welded

could

be used

pipe

and

where

tubing.

article

configuration

permits. d.

RADIOGRAPHIC of surface other

e.

TESTING

types

surface

shrink

particle)

give

TESTING cracks. better

A

J v

TYPICAL

During

of discontinuities,

ULTRASONIC

B

METHOD.

discontinuities.

STAR-SHAPED

Figure

7-13.

Not normally the

surface METHOD.

Other results,

TRANSVERSE

CRATER

indications Not

forms are

radiographic

more

CRACKSIN

normally

of NDT

economical,

HEAT-AFFECTED

C

CRACK

Surface

Shrink

(liquid

Crack

used

for

testing may used

detection for

be detected. for

penetrant and

the

of weldments

are

detection and

of magnetic

faster.

ZONE

SHRINKAGE

CRACK

AT WELD

TERMINAL

Discontinuity

7-23

THREAD

714

CRACKS

1.

CATEGORY.

Service

2.

MATERIAL.

Ferrous

3.

DISCONTINUITY

Surface.

Cracks

thread.

(See

4.

produce

cracks.

or

cracks 5.

are

NDT a.

transverse

to the

grain

(transgranular)

starting

at the

root

of the

ANALYSIS

of this flexing

type are not uncommon. act on the stress risers

Fatigue

cracks

and propagate METHODS LIQUID

Material

7-14.)

METALLURGICAL failures and/or

Wrought

CHARACTERISTICS

Figure

Fatigue vibration

and Nonferrous

may

start

in the direction

AND

penetrant

(2)

Low surface recommended

tension solvents cleaners.

(3)

When

the

such

penetrant

adjacent

and/

stresses.

is recommended

liquid

discontinuities

METHOD

Fluorescent

structure,

submicroscopic

resulting from roots and

LIMITATIONS

TESTING

(1)

applying

as fine

of applied

APPLICATION

PENETRANT

High cyclic stresses created by the thread

over

non-fluorescent.

as gasoline

and kerosene

to components

areas

should

within

be effectively

are

not

an assembly masked

or

to prevent

overspraying. b.

MAGNETIC (1)

Normally

(2)

IrreIevent ation.

(3)

Cleaning may

c.

EDDY thread ment

d.

used

TESTING

on ferrous

magnetic

titanium

result

cracks.

and

TESTING The

METHOD

materials.

indications

in structural

CURRENT

article

440C

may

result

stainless

damage

thread

configur-

hydrocarbons

material.

Not normally

configuration

the

in halogeneated

to the

METHOD.

from

would

require

used

for

detecting

speciaIized

equip-

if adaptable.

ULTRASONIC cracks.

7-24

PARTICLE

Thread

TESTING

METHOD.

configuration

does

Not

recommended

not lend

itself

for

detecting

to ultrasonic

testing.

thread

RADIOGRAPHIC

e.

thread

Surface

designed

for

tight

surface

and

extremely

A

TESTING

cracks.

COMPLETE

MICROGRAPH

the

METHOD. discontinuities

specific

condition.

connected,

their

Not recommended

for

are

by NDT

best

Fatigue

screened

cracks

detection

of this

by radiography

detecting

type

method

are

would

very

be

difficult.

THREAD

OF (A)

ROOT

SHOWING

B

FAILURE

CRACK

AT

BASE

OF

D

ROOT

TYPICAL

THREAD

ROOT

MICROGRAPH OF (B) SHOWING CRACK AT THREAD ROOT

FAILURE

TRANSGRANULAR

L

Figure

7-14.

Thread

Crack

Discontinuity

7-25

715

TUBING

CRACKS

(INCONEL

_J

1.

CATEGORY.

Inherent

2.

MATERIAL.

Nonferrous

3.

DISCONTINUITY

Tubing (See 4.

cracks Figure

CHARACTERISTICS

formed 7-15.

on the

I.D.

cracks

may

be attributed

Improper

cold

b.

Foreign

material

causing

during

Insufficient

the

in the

METHODS EDDY

may

Normally

(2)

The

for

to direction

of grain

flow.

(1)

Normally

used

(2)

A wide

Certain

of the

following:

fabrication.

embedded

on the

when

the

inner

cold

surface

worked

of the

tubes

material

was

annealing

temperature

with

possible

cracking

F range. AND

LIMITATIONS

METHOD

detection

of this

and wall

type

of discontinuity.

thickness

material

(0. 156 inch}

are

well

available

for

within

gauge

of equipment

internal

ultrasonic

RADIOGRAPHIC Not normally

have

and

have contact

an adverse

TESTING used

be difficult.

tubing. transducers

discontinuities

transducers

will

may

METHOD

on heavy

variety for

(4)

during

cracking

to the

(1 inch)

TESTING

Ultrasonic

tube

been

of ferro-magnetic

(3)

or a combination

capability.

ULTRASONIC

(1)

parallel

operation.

TESTING

used

Testing

which

7-26

rate

diameter

tubing

Co

and

1200-1400°

CURRENT

equipment

b.

have

APPLICATION

(1)

(3)

of the

annealing

heating

occurring

a.

(I.D.),

to one

reduction

embrittlement

heated

NDT

surface

ANALYSIS

a.

c.

inner

)

METALLURGICAL

Tubing

5.

"X")

for

of this varying

couplants effect

are

temperature may

on high

have nickel

METHOD detecting

tubing

screening

type.

cracks.

limitations. high

sulfur

alloys.

content

(2)

Discontinuity graphic

(3)

d.

forms

faster,

and

tubing

and

thickness

of material

govern

the

radio-

sensitivity.

Other

LIQUID

orientation

of NDT

(eddy

current

and

ultrasonic)

are

more

economical,

reliable.

PENETRANT cracks.

TESTING

Internal

METHOD.

discontinuity

Not

would

recommended

be difficult

to process

for

detecting and

interpret. eo

MAGNETIC nonferrous

PARTICLES under

TESTING

normal

METHOD.

Not applicable.

Material

is

conditions.

+LL "

TYPICAL

CRACK ON INSIDE OF TUBING SHOWING COLD LAP

C

Figure

7-15.

MICROGRAPH OF (B)

Tubing

Crack

Discontinuity 7-27

716

HYDROGEN

FLAKE

1.

CATEGORY.

Processing

2.

MATERIAL.

Ferrous

3.

DISCONTINUITY

Internal etched and

fissures

hairline

and

they cracks

parallel

bars.

4.

in a fractured

surface

aligned

CHARACTERISTICS

appear

(See

Figure

tion

are

internal

and decreased

found

o

only

in heavy

NDT

METHODS

a.

appear

They

are

as bright

silvery

Sometimes

by machining,

grain.

usually

areas.

known

flakes

are

found

in heavy

as chrome

extremely

thin

steel

On an

and

checks generally

forgings,

billets,

7-16.) ANALYSIS

fissures

attributed

solubility alloy

to stresses

of hydrogen

steel

produced

during

cooling

by localized

after

AND

TESTING

hot working.

extensively

METHOD

Used

(2)

Material in the wrought condition can be screened either the immersion or the contact method. The

for

the

the detection

method

of hydrogen

most

On the A-scan presentation, hydrogen the screen or as loss of back reflection.

(4)

AI1 foreign

materials

gouges, MAGNETIC

prior tool

(loose

to any marks,

PARTICLE used

and

TESTING

Normally

on finished

(2)

Flakes hairline

(3)

Machined surfaces of the flake.

with

(4)

Where

direction

appear as short cracks.

be necessary

general

to magnetize

flake

dirt,

Surface

scarfing

(1)

the

scale,

testing.

flake. successfully using surface condition

suited.

(3)

removed

Usually

LIMITATIONS

(!)

determine

transforma-

forgtngs.

APPLICATION

ULTRASONIC

will

b.

flakes

discontinuities.

revealed

the

METALLURGICAL

Flakes

7-28

as short

when

with

surface,

will

oil,

appear

grease)

irregularities

may

cause

loss

as hash

should such

of back

on

be as nicks,

reflection.

METHOD

machined

articles.

discontinuities

deep

tool

and

marks

may

of a discontinuity in two or more

resemble

obliterate

chrome

the detection

is questionable, directions.

checks

it may

or

e.

LIQUID PENETRANT TESTINGMETHOD. Not normally used for detecting flakes. Discontinuities are very small and tight andwould be difficult to detect by liquid penetrant.

d.

EDDY CURRENT TESTINGMETHOD. Not recommendedfor detecting flakes. The metallurgical structure of ferrous materials limits their adaptability to the use of eddy current.

e.

RADIOGRAPHICTESTINGMETHOD, Not recommende_dfordetecting flakes. The size of the discontinuity, its location and orientation with respect to the material surface restricts the application of radiography.

v,.,_

A 4340 CMSHANDFORGING REJECTEDFORHYDROGENFLAKE

CROSS-SECTION OF(A) SHOWING FLAKECONDITIONIN CENTEROFMATERIAL

Figure

7-16.

Hydrogen

Flake

Discontinuity 7-29

717

HYDROGEN

1.

CATEGORY.

Processing

2.

MATERIAL.

Ferrous

3.

DISCONTINUITY

Surface.

Small,

in highly

heat

material

exposed

4.

EMBRITTLEMENT

nondimensionaI

treated

generate

of the

5.

NDT a.

that

and

no orientation

subjected

(See

cleaning

surface

creating

METHODS

or direction.

to pickling

Figure

and/or

Found

plating

or in

7-17.)

TESTING

Magnetic

indications

(2)

Hydrogen

embritflement

particle

hydrogen

penetrates

embrittlement

and

the

sur-

cracking.

METHOD

appear

magnetic

Magnetic

This

or delayed

or electroplating

AND LIMITATIONS

(1)

the

to electroplattng

of the material.

PARTICLES

follow

prior

immediate

APPLICATION

MAGNETIC

(3)

with

ANALYSIS

at the

material

was

hydrogen.

as pickling

hydrogen

face

(interface)

material

to free

such

Service

CHARACTERISTICS

METALLURGICAL

Operations

and

as a fractured

cracks

are

pattern.

randomly

orientated

and

may

field. testing

should

be accomplished

before

and after

plating. (4)

Care or

(5)

should

cause

damage

301 corrosion but becomes

b.

LIQUID

Not normally

(2)

Discontinuities

with

(1)

Not normally

(2)

Article

used

Equipment

indications

by overheating.

cold

in the

annealed

condition,

working.

METHOD hydrogen

surface

are

plating

deposit

embrittIement.

extremely may

tight, mask

small,

the

and

difficult

discontinuity.

METHOD for

configurations

method

or irrelevant

is non-magnetic

for detecting

on the

TESTING

Recommend

7-30

steel

TESTING used

no confusing

article

resistant

Subsequent

ULTRASONIC

(3)

to the

PENETRANT

(1)

this

to produce

magnetic

to detect. c.

be taken

detecting and

size

hydrogen do not,

embrittIement. in general,

lend

themselves

of "testing. has

capability

surface

wave

of detecting_ technique.

hydrogen

embrittlement

.

to

d. F_ -J

EDDY CURRENT TESTING METHOD. Not recommended for detecting hydrogen embrittlement. Many variables inherent in the specific material may produce

e.

conflicting

RADIOGRAPHIC hydrogen

TESTING

embrittlement.

embrittlement

"

A

patterns.

is in most

DETAILED

CRACK

METHOD.

Not recommended

The sensitivity cases

in excess

PATTERN

required

for detecting

to detect

of radiographic

OF HYDROGEN

capabilities.

EMBRITTLEMENT

.

B HYDROGEN EMBRITTLEMENTUNDERCHROME PLATE

hydrogen

_:,_:

CHROME

PLATE

L.

Figure

7-17.

Hydrogen

:

.

C HYDROGEN EMBRITTLEMENT PROPAGATED TI-_I_UGH

Embrtttlement

Discontinuity

7-31

,_

*.k

718

INCLUSIONS

1.

CATEGORY.

Processing

2.

MATERIAL.

Ferrous

3.

DISCONTINUITY

Surface

and

metallic weldment. 4.

may (See

singly

Figure

inclusions

to the weld

are

metal.

METHODS

NDT

b.

e°

globules

or non-

throughout

appear

absorbent

material

absorbent

materials

Forci_ material test results. CURRENT

Normally

(2)

Established obtained.

MAGNETIC (1)

Normally

(2)

Confined

density

oxides,

weld

the

as compared

sulphides,

or between

slag

the

weld

or metal

appear

on the

throughout

in the

zone

fusion

is indicated

not used to machined

wall

may

or at the

film scales,

shadows

contours

of

occurring They

root

of the

weld.

film

density

and

wilI Less more

density. splatter,

welded

or flux may invalidate

tubing.

be required

TESTING for

round, or in

METHOD

to thin

standards

PARTICLE

as loose

shaped

as

the weldment.

by a greater

by a lighter

confined

radiograph

or irregularly

or scattered

such

as sharply defined, and may be isolated

groups. will

TESTING

surface.

used.

appear on the radlograi_h or elongated white spots

or elongated

linearly,

(1)

are

in the

is universally

inclusions

generally

EDDY

be metallic

AND LIMITATIONS

or scattered

Non-metallic

or near 7-_2

method

linear

singly,

(4)

may

or scattered

of different

inclusions

entrapped

inclusions shaped,

erratically

round

They

TEsTINGMETHOD

(2) Metallic

(3)

shape.

distributed

of metals

Non-metallic

APPLICATION

small

be any

particles

material

RADIOGRAPHIC

(i) This

may

or be linearly

generally

foreign

a.

Material

ANALYSIS

or base

NDT

Welded

7-18.)

other non-metallic and the base metal. 5.

Nonferrous

Inclusions

appear

METALLURGICAL

Metallic

and

CHARACTERISTICS

subsurface.

and

(Weldments)

detecting weldments

if valid

results

are

to be

METHOD inclusions where

in weldments. the

discontinuities

are

surface

V

(3)

The

indications

would

or clustered, (4)

Discontinuities between

d,

(2)

Specific

:., .... e.

E

¸

used

applications testing::

open

Jagged,

irregularly

shaped,

not be too pronounced.

go undetected

magnetic

L_QUm PEN'ETRAN_ arelormaiiynot

would

may

TESTING

Not normally

ultrasonic

.............

the

ULTRASONIC (1)

and

appear

particles

when and

the

indivtdually

-

improper surface

Conta6texists of the

•

article.

METHOD for

detecting............ inclusions.: _:: of:design

oi" of article

_ _: ............... ...... _'_T:'_." .... ,>_, _ configuration

may

-

l'equire-

i--..:_ _=:__,_,:,_ _ ,_._ ;_7_ , ,i__ -v_,_i _ii.,_ .>iii,_:).,_.,._-_,,, _ E-ST!_-G

_,.E.T_OD

.Nqt applicable,

Inclasions

fissures.

,

0 7-33

:: ;_,;

719

INC LUSIONS

1.

CATEGORY.

Processing

2.

MATERIAL.

Ferrous

3.

DISCONTINUITY

Subsurface Often

with

short

and

and

rolled

4.

or

long

straight

mass (See

METALLURGICAL

billet state

during

5.

NDT

METHODS

a.

(after lines

machining).

There

parallel

in groups.

to flow lines

The

and not parallel Figure

7-19.

(stringers)

Non-plastic

solid

Material

other

type

to flow

lines.

are and

two quite

types:

one

tightly

adherent.

is non-plastic, Found

appearing

in forged,

as

extruded,

)

ANALYSIS

inclusions or ingot.

surface

to occur

large

material.

Non-metallic the

bar)

likely

a comparatively

Wrought

CHARACTERISTICS

(original

is non-metallic

and Nonferrous

billet

are

caused

inclusions

are

by the

existence

caused

by particles

of slag

or oxides

remaining

in

in the

melting. APPLICATIONS

ULTRASONIC

TESTING

(1)

Normally

used

(2)

Inclusions

will

AND

LIMITATIONS

METHOD

to evaluate appear

inclusions

as definite

in wrought interfaces

clustered condition or conditions on different back reflection. Numerous small scattered

material.

within

the

metal.

planes causing conditions cause

Small a loss in excessive

"noise". (3) Inclusion orientation in relationship to ultrasonic beam (4) The direction of the ultrasonic beam direction of the grain flow whenver b.

EDDY

CURRENT

(i) Normally

TESTING

MAGNETIC

used for thin wail tubing and small diameter rods.

PARTICLE

(i) Normally

should be perpendicular to the possible.

METHOD

(2) Testing of ferro-magnetic c.

is critical.

TESTING

used on machined

materials can be difficult. METHOD surface.

(2) Inclusions will appear as a straight intermittent or as a continuous indication. They may

be individual or clustered.

(3) The magnetic technique should be such that a surface or near surface inclusion can be satisfactorilydetected when its axis is in any direction.

7-34

(4) A knowledge of the grain flow of the material will be parallel to that direction. (5)

Certain

types

of steels

are

more

prone

is critical

to inclusions

since

than

inclusions

other.

i i

d,

f e.

LIQUTD

PENETRANT

(i)

Not normally

(2)

Inclusions

RADIOGRAPHIC designed

TESTING used

for detecting

are generally TESTING

for surface

METHOD inclusions

not openings

METHOD.

in wrought

in the material

material. surface.

Not recommended.

testing are more

suitable for detecting

NDT

methods

surface

inclusions.

== =

]

C

TYPICAL INCLUSION PATTERN ON MACHINED SURFACES

B STEEL FORGINGSHOWINGNUMEROUS INCLUSIONS

J C

MICROGRAPH

OF TYPICAL

Figure

INCLUSION

7-19.

Wrought

D

Inclusion

LONGITUDINAL CROSS-SECTION ORIENTATION OF INCLUSIONS

SHOWING

Discontinuity

7-35

720

LACK

OF

PENETRATION

i.

CATEGORY.

Processing

2.

MATERIAL.

Ferrous

3.

DISCONTINUITY

Internal

or external.

running 4.

parallel

Generally

with

by root

deposited. bead.

,

NDT a.

face

Also

the

(2)

by fast

7-20.

fusion

welding

rate,

AND

TESTING

oeeuring

at the

root

and

metal

was

)

extensively

temperature too large

before

a welding

weld rod,

or too

cold

a

LIMITATIONS

METHOD

on a wide

variety

of welded

articles

to determine

the

of penetration.

Lack

of penetration

area

of varying appear

(3)

Lack of penetration source is critical.

(4)

Sensitivity levels di s c ontinuitie s.

ULTRASONIC (1)

Commonly

(2)

Complex

wilI

used weld

appear

length

and

in the

center

on the

width.

govern

for

radiograph

It may

of the

orientation

TESTING

themselves

7-36

Figure

APPLICATION

and may bends.

b.

(See

and filamentary

not reaching

RADIOGRAPHIC Used

irregular

weld.

of joint

caused

lack

Weldments

ANALYSIS

METHODS

(1)

Nonferrous

CHARACTERISTICS

METALLURGICAL

Caused

and

weld

capability

dark

or intermittent

at the

of multipass

in relationship

the

as an elongated

be continuous junction

to the

to detect

radiographic

small

or tight

METHOD specific

applications.

configurations,

to ultrasonic

(3)

Lack of penetration will discontinuity resembling

(4)

Repeatability is standardized.

of ultrasonic

or thin

wail

weldments

do not

lend

testing. appear on the scope as a definite break or a crack and will give a very sharp reflection. test

results

is difficult

unless

equipment

c.

EDDY

CURRENT

(i) Normally

TESTING

METHOD

used to determine lack of penetration in nonferrous welded

pipe and tubing. (2) Eddy current can be used where the configuration requirement d.

MAGNETIC

PARTICLE

(i) Normally (2) e.

Lack

LIQUID

of penetration

k.J

appears

PENETRANT

Normally

(2)

Lack of penetration width.

(3)

Residue

used

left

where

Figure

of varying

width.

of weld

is visible.

as an irregular

and

the

indication

developer

could

of varying

contaminate

operation.

INADEQUATE

PENETRATION

7-20.

penetrant

indication

METHOD

backside appears

by the

re-welding

INADEQUATE ROOT WELDED TUBE

METHOD

as an irregular

TESTING

A

B

TESTING

used where backside of weld is visible.

(1)

any

other nonferrous articles can meet

of the equipment.

OF BUTT

Lack

ROOT

PENETRATION

C

INADEQUATE FILLET KNOWN AS BRIDGING

of Penetration

WELD

PENETRATION

Discontinuity

7-37

721

LAMINATIONS

1.

CATEGORY.

Inherent

2.

MATERIAL.

Ferrous

3.

DISCONTINUITY

Surface

and internal.

surface

of the

Found

in forged,

4.

surface

of the

or segregations tened

o

Fiat,

material.

May

a.

and

material. elongated that

are

or weaknesses They

may

and

made

Numerous

Lamination reflection.

(4)

Through very

thin

MAGNETIC

c.

Articles

gauge

to the wave

material

7-38

Figure

7-21.)

aligned

parallel

their

may

blister,

surfaces.

to the work

seam,

inclusions,

Laminations

are

orientation

limited

depending

upon

for testing. Automatic are adaptable.

as a definite

and

and

detection

be used

selected methods

transmission

flat-

interface

reflection

with

techniques

are

of lamination

to ultrasonic. the

material

and

a loss

manual

of back

applicable

for

sections. TESTING

fabricated

from

by magnetic indication

(3)

Magnetic

particle

or depth PENETRANT

Normally

of pipe, by working.

the geometry

makes

appear

Magnetic

(1)

the

work

AND LIMITATIONS

modes

will

result

directional

beam)

(2)

LIQUID

(See

between

to the

METHOD

PARTICLE

lamination

size

of oxide

parallel

thin.

TESTING

heavier

(3)

(I)

aligned

generally

be the

thickness or method contact or immersion

b.

film

material.

APPLICATION

(normal (2)

generally

a thin

roiled

extremely

ULTRASONIC For

Material

ANALYSIS

METHODS

(i)

Wrought

thin,

contain

separations

impurities NDT

extremely

extruded,

are

Nonferrous

CHARACTERISTICS

METALLURGICAL

Laminations

and

used

will

ferrous

materials

are

normally

tested

for

particle. appear

testing

of the

METHOD

as a straight,

is not

capable

lamination.

TESTING on nonferrous

METHOD materials.

intermittent

of determining

indication. the

over-alI

(2)

Machining, and

(3)

honing,

thereby

Acid

and

testing. do

EDDY tions.

ej

or blasting

close

or mask

surface

alkalines

seriously

limit

Thorough

cleaning

of the

CURRENT If used,

lapping,

TESTING the

RADIOGRAPHIC

method

TESTING

laminations

Laminations

of the X-ray

beam,

the

have

thereby

effectiveness

surface

very

making

surface

of material

of liquid

penetrant

is essential.

Not normally

be confined

METHOD.

smear

lamination.

METHOD. must

may

Not small

used

to thin

sheet

to detect stock.

recommended thickness

radiographic

lamina-

changes detection

for

detecting in the

almost

direction impossible.

i i

! I

! i

_7

A

C

LAMINATION

IN 0.250

B

IN. PLATE

D

LAMINATION IN PLATE SHOWING SURFACE O'RIENTATION

Figure

7-21.

LAMINATION

LAMINATION

IN 0.040

TITANIUM

SHEET

IN 1 IN. BAR SHOWING SURFACE

ORIENTATION

Lamination

Discontinuity

7-39

722

LAPS

AND SEAMS

1.

CATEGORY.

Processing

2.

MATERIAL.

Ferrous

3.

DISCONTINUITY

Surface.

Wavy

cracks.

Found

and

in direction

4.

and

Nonferrous

Rolled

Threads

CHARACTERISTICS

lines,

often

in rolled

quite

deep

threads

of rolling.

METALLURGICAL

(See

and

sometime

in the

minor,

Figure

7-22.)

pitch,

very

tight,

appearing

and

major

diameter

as hairline of the

thread,

ANALYSIS

During the rolling operation, cause material to be folded

faulty or oversized dies or an overfill of material may over and flattened into the surface of the thread but not

fused.

.

NDT a.

METHODS LIQUID

APPLICATION PENETRANT

AND

TESTING

LIMITATIONS METHOD

(1) Compatibility with both ferrous and nonferrous materials makes fluorescent liquid penetrant the first choice. (2) Liquid penetrant indications will be circumferential, slightlycurved, intermittent or continuous indications. Laps and seams

may

occur

individuallyor in clusters. (3) Foreign material may not only interfere with the penetration of the penetrant into the discontinuitybut may

cause an accumulation of

penetrant in a nondefective area. (4) Surface of threads may be smeared

due to rolling operation, thereby

sealing offlaps and seams. (5) Fluorescent and dye penetrants are not compatible.

Dye penetrants

tend to killthe fluorescent qualities in fluorescent penetrants. b.

MAGNETIC

PARTICLE

TESTING

METHOD

(1) Magnetic particle indications would generally appear the same

as

liquid penetrant. (2) Irrelevent magnetic indications may

result from the thread

configuration. (3) Questionable magnetic particles indications can be verified by liquid penetrant testing.

7-40

e.

EDDY laps

d.

and

TESTING

seams.

ULTRASONIC and

e.

CURRENT

seams.

Article TESTING

Thread

RADIOGRAPHIC and seams.

Size

Not

orientation

restricting

recommended

restrict

METHOD.

used

detecting

factor. for

ultrasonic

detecting

laps

capability.

Not recommended

of discontinuities

for

for

restricts

detecting

Iaps

the capability

testing.

A

TYPICAL

B

C

7-22.

is the

METHOD.

configurations

and

Not normally

configuration

TESTING

of radiographic

Figure

METHOD.

FAILURE

AREAS

Laps

AREAS

OCCURRING

WHERE

and

OF FAILURE

LAPS

Seams

AND

AT

LAPS

ROOT

SEAMS

AND

SEAMS

OF THREAD

USUALLY

Discontinuity

OCCUR

in Rolled

Threads

7-41

723

LAPS

AND SEAMS

%J i.

CATEGORY.

Processing

2.

MATERIAL.

Ferrous

3.

DISCONTINUITY Lap

a.

(See

Seams

are

operations. surface 5.

may but not

NDT a.

often

quite

grain

and

the

blowholes,

the

exist

deep

forgings,

and

at times

MAGNETIC (1)

Magnetic

(2)

Surface method.

and

may

processing the

Laps

splits,

direction

discontinuity

during

fused.

METHODS

cracks,

in the

to seams

During

an overfill

Laps

adherent

may

plate,

have

surface

tubing,

bar,

sometimes spiral

very

when

tight,

usually

associated

with

ANALYSIS

of the

similar

in wrought

or tightly

angle.

tubing.

elongated

innerfaces

pronounced

at a small

7-23.)

with

and

from

and

Material

not very

surface Found

Lengthy,

fissures rod

originate

adjacent Laps

Figure

METALLURGICAL

processing

Wrought

usually the

closed.

Surface.

rolled

lines enter

smeared

parallel

4.

usually

rod.

Seam

Do

Wavy

they

openings and

Nonferrous

CHARACTERISTICS

Surface.

since

and

is very from

of the

material,

APPLICATION PARTICLE

(3) Laps and indication.

seams

may

They

may

laps

appear

forging,

may

be folded

being

flattened

corners

part

between

or sizing over

or

into the

of the article.

METHOD

is recommended

and near-surface

distance

LIMITATIONS

TESTING

particle

in earlier

The

roiling,

in material

on any AND

introduced

improper

resulting

occur

tears

or forging.

small.

result

sizing

may

and

of roiling

and

for ferrous

material.

seams

be detected

may

as a straight,

be individual

spiral,

or clustered

by this

or slightly and

curved

continuous

or

intermittent.

(4)

Magnetic

buildup

magnetizing crack

(5) Correct

current

and

greater

seams than

is very that

used

small. for

the

Therefore, detection

a of a

is necessary. magnetizing

forging laps since to the surface.

7-42

of laps

technique the

discontinuity

should

be used

may

lie

when

examining

for

in a plane

nearly

parallel

LIQUID

b°

PENETRANT

(1)

Liquid

(2)

Laps

penetrant and

c.

be very

tight

and

material.

difficult

to detect

TESTING

(1)

Normally

used

(2)

Surface

wave

length,

and

Normally

(2)

Other tion

and

size

and

Figure

7-23.

to machining.

evaluation

of the

depth,

seams. and

seams

will

appear

as definite

inner

METHOD

for

the

can

be screened

evaluation

of laps by eddy

and

seams

current

in tubing

where

article

and

pipe.

configura-

permit. METHOD.

in wrought

direction of the X-ray _ 1m,_,_l imnnssible.

TYPICAL

prior

accurate

material.

Not recommended Although

discontinuity size and the material thickness _in most cases, discontinuities have a very

A

slightly

metal.

TESTING

seams

and

of laps

TESTING

articles

material

permits

of Iaps

the

used

RADIOGRAPHIC laps

technique

CURRENT

(1)

wrought

indication

within

improved

METHOD

to test

size

Ultrasonic

EDDY

especially

penetrant.

ULTRASONIC

faces

e.

may

for nonferrous

Liquid penetrant testing of laps and seams can be by heating the article before applying the penetrant.

(3) d.

METHOD

is recommended

seams

by liquid (3)

TESTING

FORGING

Laps

beam,

thereby

making

Seams

Discontinuity

ratio

detecting

between

the

exceeds 2 % of sensitivity small thickness change in the radiographic

B

LAP

and

the

for

MICROGRAPH

in Wrought

detection

OF A LAP

Material 7-43

724

MICRO-SHRINKAGE

1.

CATEGORY.

Processing

2.

MATERIAL.

Magnesium

3.

DISCONTINUITY

Casting

CHARACTERISTICS

Internal. Small filamentary voids in the grain boundaries appear as concentrated porosity in cross section. 4.

METALLURGICAL

Shrinkage molten

metal

void.

The

occurs. stituent

.

occurs

ANALYSIS

while

cannot void

a.

the metal

flow

METHODS

is in a plastic

into different

is identified

Micro-shrinkage from the grain NDT

(See Figure 7-24.)

by its

is caused boundaries. APPLICATION

areas

AND

semi-molten

as it cools,

appearance by the

or

the

and by the withdrawal

state.

If sufficient

shrinkage

time

will

in the plastic

of the low melting

leave range

point

LIMITATIONS

TESTING

(i) Radiography

is universally used to determine the acceptance level

METHOD

of micr0-shrinkage.

resembling

it

con-

RADIOGRAPHIC

(2) Micro-shrinkage

a

.....

will appear on the radiograph as an elongated swirl

feathery streaks or as dark irregular patches, which are

indicative of cavities in the grain boundaries. b.

LIQUID

PENETRANT

TESTING

METHOD

(1) Normally_t!sed on finished machined (2) Micro-shrinkage

surfaces.

is not normally open to the surface.

will, therefore, be detected in machined (3) The appearance

conditions

of the indication depends on the plane through which

the condition has been cut. The appearance hairline to a massive (4) Penetrant may

These

areas.

varies from a continuous

porous indication.

act as a contaminant by saturating the micro

porous

casting affectingtheir abilityto accept a surface treatment. (5) Serious structural and a dimensional damage

to the article can result

from the improper use of acids or alkalies. They should never be used unless approval is obtained.

7-44

c.

EDDY

CURRENT

micro-shrinkage. themselves d.

e.

to eddy

ULTRASONIC

TESTING

METHOD.

Article

configuration

Not and

recommended type

for

detecting

of discontinuity

do not lend

current.

TESTING

shrinkage.

Cast

structure

MAGNETIC

PARTICLE

METHOD. and TESTING

Not recommended

article

for

configuration

METHOD.

Not

are

detecting

restricting

applicable.

microfactors.

Material

is

nonferrous.

BUSHING

=i. -

ACK

£

A

B

F

CRACKED MAGNESIUM HOUSING

C

CLOSE-UP VIEW OF (A)

Figure

7-24.

Micro-Shrinkage

MICROGRAPH OF CRACKED AREA

Discontinuity

7-45

725

GAS POROSITY

1.

CATEGORY.

Processing

2.

MATERIAL.

Ferrous

3.

DISCONTINUITY

Surface

or

groups. 4.

also

be concentrated

in welds

on the base NDT a.

Weldments

or elongated,

Scattered

METALLURGICAL

Porosity

5.

Rounded

at the point. May

Nonferrous

CHARACTERISTICS

subsurface.

discontinuity

and

at the

root

shaped

throughout

the

or toe.

(See

in the

molten

with weld

Figure

or without or isolated

7-25.

a sharp in small

)

ANALYSIS

is caused

or filler

teardrop

uniformly

by gas

metal,

METHODS

entrapment

or improper

APPLICATION

RADIOGRAPHY

cleaning AND

TESTING

metal,

too much

moisture

or preheating.

LIMITATIONS

METHOD

(1) Radiography is the most universally used NDT of gas porosity in weldments.

method

for the detection

(2) The radiographic image of a 'round' porosity will appear as oval shaped spots with smooth edges, while 'elongated' porosity will appear as oval shaped spots with the major

axis sometimes

several times

longer than the minor axis. (3) Foreign material such as loose scale, flux, or splatterwill affect validity of test results. b.

ULTRASONIC

TESTING

METHOD

(1) Ultrasonic testing equipment is highly sensitive, capable of detecting micro-separatlons. Established standards should be used if valid test results are to be obtained. (2) Surface finish and grain size will affect the validityof the test results. c.

EDDY

CURRENT

(1) Normally

TESTING

METHOD

confined to thin wall welded pipe and tube.

(2) Penetration restricts testing to a depth of more d.

LIQUID

PENETRANT

TESTING

than one-quarter inch.

METHOD

(1) Normally confined to in-process control of ferrous and nonferrous weldments.

7-46

e.

(2)

Liquid surface

(3)

Extreme

caution

magnetic

(iron

entrapped

and

MAGNETIC

penetrant testing, evaluation. must oxide),

Not normally

used

(2)

Only surface

porosity

A

TYPICAL

SURFACE

C

to detect

defined

POROSITY

7-25.

is restricted

any

penetrant

materials

the rewelding

operation.

cleaning from

to

material, becoming

METHOD gas

porosity.

would

be evident.

Near

since

it is neither

strong

B

MICROGRAPH OF CROSS-SECTION SHRINKAGE POROSITY

Figure

particle,

to prevent

and liquid

TESTING

(1)

magnetic

be exercised

contaminating

PARTICLE

not be clearly

like

Gas Porosity

CROSS-SECTION POROSITY

SHOWING

surface

porosity

would

or pronounced.

OF (A)SHOWING

EXTENT

OF

TYPICAL

Discontinuity

7-47

726

POROSITY

UNFUSED

1.

CATEGORY.

Processing

2.

MATERIAL.

Aluminum

3.

DISCONTINUITY

Internal.

Wafer-thin

aluminum

which

4.

CHARACTERISTICS fissures

is rolled,

porosity

forging, surface

of these fuse

,

is attributed

NDT a.

the

Used

(2)

Material

(3)

Ultrasonic

extensively

Where

may

the

general

of manufacture

PENETRANT used

(2)

Unfused

porosity

Surface obliterate

)

Excessive

from

wrought

During

the

If the

of a foreign

rolling,

internal

material,

in an extremely

they

thin interface

and

machined

it may

be

configuration

porosity

to the

will material

articles.

the

grain.

Liquid

the

directions.

METHOD

as a straight

of liquid

three

is unknown,

article

unfused

appear

by masking

in all

discontinuity

subsequent of the

such

void

configuration.

directions.

will

preparations

porosity.

as received of the

of the

several

on nonferrous

agitation

ingot. shape.

of unfused

location

TESTING

with

reliability

the

orientation

Normally

(4)

in wrought

LIMITATIONS

direction

Method

the

cast

resulting

in the

fixes

to test

the

7-26.

is in the

the detection

be tested

testing

ning parallel evaluation.

7-48

for

(1)

(3)

Figure

Found

METHOD

necessary

LIQUID

flow.

or is composed

AND

TESTING

determine surface. b.

grain

into wafer-thin

processing,

APPLICATION

(1)

which

is oxidized

subsequent

ULTRASONIC

(5)

the

(See

it is flattened

discontinuities

METHODS

(4)

with

or extruded.

to porosity

operations

during

parallel

ANALYSIS

or extruding

will not or void.

aligned forged,

METALLURGICAL

Unfused

kj

as vapor surface

penetrant

of powder

line

penetrant

blasting,

of varying

lengths

is restricted

honing,

discontinuities,

to surface

or sanding

thereby

run-

may

restricting

testing. in a large

container

may

produce

foaming.

c.

d.

EDDY

CURRENT

unfused

porosity.

TESTING

RADIOGRAPHIC (1)

Not

(2)

Wafer-thin

TESTING

normally

e.

MAGNETIC

used

density

perpendicular

for

detecting

or

are which

to the

PARTICLE

Not

normally

used

for

detecting

METHOD

discontinuities

measures and

METHOD.

unfused difficult

to detect

requires X-ray

TESTING

porosity.

that

the

by

a method

discontinuity

which be

parallel

beam. METHOD.

Not

applicable.

Material

is

nonferrous.

A

FRACTURED SPECIMEN SHOWING UNFUSED POROSITY

C

B

TYPlCAL UNFUSED POROSITY

UNFUSED POROSITY EQUIVALENT TO 1/64, 3/64, 5/64 AND 8/64 (LEFT TO RIGHT)

D

ULTRASONIC SCOPE PATTERN OF (C)

S

rF.,.j

Figure

7-26.

Unfused

Porosity

Discontinuity

7-49

727

STRESS

CORROSION

1.

CATEGORY.

Service

2.

MATERIAL.

Ferrous

3.

DISCONTINUITY

Surface.

Range

material;

however,

4.

factors

from

shallow

3) the use is much type

deep,

cracks

are

and usually also

follow

possible.

the

(See

grain

Figure

flow

of the

7-27.)

ANALYSIS

necessary

static

for

tensile

of a material more

to very

transverse

are

1) a sustained

The

CHARACTERISTICS

METALLURGICAL

Three

and Nonferrous

likely

of stresses

the

phenomenon

stress,

that

of stress

2) the presence

is susceptible

to occur

faster

include

residual

to this

at high

type

levels

(internal)

corrosion

to occur:

of a corrosive

environment,

of failure.

of stress as well

Stress

and

corrosion

than at low levels

as those

from

of stress.

external

(applied)

loading.

.

NDT a.

METHODS LIQUID

APPLICATION

PENETRANT

TESTING

(1)

Liquid

penetrant

(2)

In the

preparation,

care the (3)

must

may

METHOD

is normally

used

application,

be exercised

surrounding

Chemical

AND LIMITATIONS

for

the

detection

and final

to prevent

over

cleaning spraying

of stress

corrosion.

of articles,

extreme

and

contamination

of

articles.

cleaning

seriously

immediately

affect

the

before

test

results

the if the

application

of Iiquid

solvents

are

penetrant

not given

time

evaporate. (4)

Service will

articles

dilute,

may

contain

contaminate,

moisture

and

invalid

within results

the

discontinuity

if the

moisture

which is not

removed. b.

EDDY

CURRENT

Not normally

used

(2)

Eddy

equipment

article c.

ULTRASONIC

configuration TESTING

(1)

Not normally

(2)

Discontinuities surface

7-50

TESTING

(1)

current

V

used

technique.

are

METHOD

to detect

stress

is capable is compatible

corrosion. of resolving with

stress

equipment

corrosion

where

limitations.

METHOD to detect

stress

perpendicular

corrosion. to surface

of material

and

require

to

d.

e.

MAGNETIC PARTICLE (1)

Not normally

(2}

Configuration

of article

netic

testing.

particle

RADIOGRAPHIC

to detect

TESTING

(1)

Not normally

(2)

Surface

used

indications

application. with

used

TESTING

the

of the

stress

and usual

corrosion. nonmagnetic

condition

exclude

mag-

METHOD

to detect are

However, use

METHOD

proper

stress

best

detected

radiography

corrosion. by NDT can

method

and has

shown

designed stress

for

such

corrosion

technique.

%.v

FRACTURED ALUMINUM ALLOY DUE TO STRESS CORROSION

COUPLING

-----7 ¸¸

Figure

7-27.

Stress

Corrosion

Discontinuity

7-51

728

HYDRAULIC

1.

CATEGORY.

2.

MATERIAL.

3.

DISCONTINUITY

Surface

and

deep.

.

internal. they

in the

c.

Seams

which

in the

eariler

are

are

the

from

processing,

Figure

(1)

Universally

which

to very

flow with

tight the

and

exception

7-28.)

(2)

Heavier

walled

to the

tubing

(3)

The specific fined.

nature

(4)

Test

may

(5)

Testing

(6)

All material should the test results.

results

cracks,

over splits

elongated

and

being

not fused.

and tears

during

to the presence

of nonferrous

(0. 250 and

introduced

rolling.

of a corrosive

environ-

be successfully

tested

may

unless

may

controlled

material

may

of any

not

equipment.

discontinuities

not be valid

be free

tubing.

above)

of the

of various

for

folded

and

LIMITATIONS

ability

TESTING used

material

METHOD

of ferro-magnetic

PENETRANT

the tube

are

is due

for testing

penetration

following:

being

then

AND

TESTING used

of the

blowholes, and

APPLICATION

CURRENT

one

of material

corrosion

METHODS

LIQUID

shallow

of the grain (See

in contact with of the tube.

result

originate

Intergranular ment.

due

to long,

direction

usually

material coming into the surface

which

EDDY

short

no direction.

discontinuities

Laps

b.

has

from

ANALYSIS

b.

NDT

in size

be found

which

Foreign embedded

a.

7-52

will

corrosion,

tubing

Service

6061-T6

Range

a.

d.

and

CHARACTERISTICS

METALLURGICAL

Hydraulic

o

Processing Aluminum

Usually

of stress

TUBING

foreign

not be clearly

by known

standards.

be difficult. material

that

would

METHOD

(I)

Not normally

detecting

(2)

Eddy current is more economical, standards is more reliable.

tubing

discontinuities.

faster,

de-

and with

established

invalid

c.

ULTRASONIC

TESTING

METHOD

L=

(1)

Not normally

used

(2)

Eddy

is recommended

current

for

and more economical ferrous material. d.

RADIOGRAPHIC Not normally

(2)

The

size

for

TESTING

(1)

used

and type

detecting

MAGNETIC

over

this

for

ultrasonic

range

detecting

testing

of surface

tubing

of discontinuity

PARTICLES

discontinuities. since

it is faster

discontinuity

and non-

METHOD

limit the use of radiography of discontinuities. e.

tubing

TESTING

discontinuities.

and the

for

screening

METHOD.

configuration of material

Not

of the for

applicable.

this

article group

Material

is nonferrous.

A

C

INTERGRANULAR

EMBEDDED

B

CORROSION

FOREIGN

D

MATERIAL

TWIN

LAPIN

LAPS

OUTER

SURFACE

IN OUTER

OF

SURFACE

TUBING

OF TUBING

,F "N_./"

Figure

7-28.

Hydraulic

Tubing

Discontinuity

7-53

729

MANDREL

DRAG

i.

CATEGORY.

Processing

2.

MATERIAL.

Nonferrous

3.

DISCONTINUITY

V Thick-Wall

Seamless

CHARACTERISTICS

Internal surface of thick-wall tubing. Range tears.

Tubing

from

shallow even gouges to ragged

Often a slug of the material will be embedded

within the gouged area. (See

Figure 7-29. ) 4.

METALLURGICAL

During

the

passes

through

the

portion

of the

material

the

5.

manufacture

surface

Certain

of the

types NDT a.

b.

ANALYSIS of thick-wail

offset

roils. may

tubing

METHODS EDDY

As the

break

may

of material

seamless

more

prone

for

(2)

Eddy

current

testing

(3)

Discontinuities

are

(4)

Several

simultaneously

TESTING

(1)

used

NormaIly

follows

this

the

mandrel.

over slug

type

embedded

of failure

fracture,

into than

as it' a

As it does the

walI.

others.

METHOD

Normally

ULTRASONIC

the

to this

(i)

factors

mandrel

is ruptured

AND LIMITATIONS

TESTING

used

the billet

and be forced or have

APPLICATION

CURRENT

piercing

loose

be scored

are

tubing,

the

testing may

of thin-wall

be confined

qualitative,

pipe

or tube.

to nonferrous

not quantative affect

output

V

materials.

indications. indications.

METHOD

for

the

screening

of thick-wail

pipe

or tube

for

mandrel

drag. (2)

Can be used

(3)

Requires

i4)

May be used

access

automatic (5)

Configuration noticeable

c.

RADIOGRAPHIC (1)

Not normally of mandrel

(2)

7-54

to test

both

from

in support

ferrous one

side

and

nonferrous

pipe

or tube.

only.

of production

line

since

it is adaptable

for

instrumentation. of mandrel indications

on the

TESTING used drag

Complete coverage of the tube.

drag

or tear

will produce

very

sharp

and

scope.

METHOD

although during

it has

examination

requires

several

been

instrumental

of adjacent exposures

in the

detection

welds. around

the

circumference

(3)

(4)

This

method

slow

and

Radiograph

LIQUID

do

f

mandrel e.

is not

costly

for

will

A

PARTICLE

ing mandrel

drag.

EMBEDDED

C

SLUG

SHOWING

TESTING

Discontinuities particles.

DEEP GOUGE

ANOTHER TYPE OF EMBEDDED

Figure

only

discontinuity

MAGNETIC

7-29.

production

support

of pipe

or tube.

volumes

TESTING

since

detectable by magnetic less stainless steel.

C

for

large

disclose

PENETRANT drag

designed

two dimensions

METHOD.

not

Not close

mandrel

B

MARKS

Drag

third. for

recommended

enough drag

detecting

not be detectable.

to the will

occur

for surface

detectto be

in seam-

SLUG BROKEN LOOSE FROM TUBING WALL

D

SLUG

Mandrel

and wouId

METHOD. are

not the

it is very

Not recommended

is internal

Most

and

since

GOUGE ON INNER SURFACE OF PIPE

Discontinuity

7-55

730

SEMICONDUCTORS

k.$ 1.

CATEGORY.

Processing

2.

MATERIAL.

Hardware

3.

DISCONTINUITY

Internal.

Appear

be misformed, diodes, 4.

aligned,

sizes

loose

leads,

or voids

.

NDT a.

and

(See

various

internal

Figure

degrees hardware.

7-30.

of density. Found

They

may

in transistors,

)

ANALYSIS

discontinuities

such

clearance

or around

METHODS

shapes

or broken

capacitors.

inadequate

in seals

and

damaged,

and

METALLURGICAL

Semiconductor

Service

CHARACTERISTICS

in many

resistors,

and

lead

as loose

internal

connections

are

APPLICATION

RADIOGRAPHIC

wire,

between

TESTING

AND

weld

splash,

elements the

flakes, and

product

case,

solder and

of processing

balls,

inclusions errors.

LIMITATIONS

METHOD

(i) Universally used as the NDT in semiconductors.

method

for the detection of discontinuities

(2) The configuration and internal structure of the various semiconductors limit the NDT

method to radiography.

(3) Semiconductors

that have copper heat sinks may

require more

than one

technique due to the density of the copper. (4) Internal wires in semiconductors

are very fine and may be constructed

from materials of differentdensity such as copper, silver, gold and aluminum, may

If the latter is used with the others, special techniques

be needed to resolve its reliability.

(5) Micro-particles may

require the highest sensitivityto resolve.

(6) The complexity of the internal structure of semiconductors

may

require additional views to exclude the possibilityof non-detection of discontinuities due to masking

by hardware.

(7) Positive positioning of each semiconductor

will prevent invalid

interpretation. (8) Source angle should give minimum (9) Preliminary

distortion.

examination of semiconductors

may be accomplished

using

a vidcon system that would allow visual observation during 360 degree rotation of the article.

V 7-56

EDDY

b,

CURRENT

semiconductor

E-

struction c.

TESTING

METHOD.

discontinuities.

of the

MAGNETIC

article

themselves

TESTING

METHOD.

LIQUID PENETRANT TESTING semiconductor discontinuities.

e.

ULTRASONIC

A

STRANDS

to this

for detecting and method

form

of con-

of NDT.

Not recommended

for

detect-

discontinuities.

d.

conductor

of discontinuity

do not lend

PARTICLE

ing semiconductor

Not recommended

Nature

TESTING

METHOD.

Not recommended

METHOD.

Not recommended

for

for

detecting

detecting

semi-

discontinuities.

BROKEN

IN HEATER

BLANKET

FINE

CRACK

IN PLASTIC

CASING

MATERIAL

{

C

BROKEN

ELECTRICAL

Figure

D

CABLE

7-30.

Semiconductor

FOREIGN

MATERIAL

WITHIN

SEMICONDUCTOR

Discontinuity

7-57

731

HOT

TEARS

i.

CATEGORY.

Inherent

2.

MATERIAL.

Ferrous

3.

DISCONTINUITY

Internal

or near

branches. 4. Hot

Appear

singly

(tears)

the

Tears

may

sections

NDT a.

caused

of the

metal

where

stresses

heavier

masses

METHODS

RADIOGRAPHIC

TESTING

Radiographic

(2)

(3)

(2)

The sensitivity tears.

Hot tears

that

magnetic

particIe

Article

co

7-58

set

Foreign test.

LIQUID

and numerous

in stresses

is still

up by the more

AND

LIMITATIONS

first

are

choice may

in the rapid

slower

which

brittle

range.

cooling

of thin

to cool.

since

the

be internal

in relation

to the

material and

source

is cast

surface.

may

influence

kJ not be sufficient

TESTING

are

resulting

which

may

exposed

to detect

fine

surface

can be screened

with

hot

METHOD to the

surface

method.

configuration

Although

cooling

discontinuities

PARTICLE

and

metallurgical

composition

may

make

difficult.

magnetic

radiography (4)

width

7-31.)

of metal,

is the

level

demagnization (3)

Figure

temperature

Orientation of the hot tear the test results.

MAGNETIC (1)

of variable

METHOD

testing and the

its are

APPLICATION

structure

b_

while

adjoin

(1)

(See

by non-uniform

originate

that

line

ANALYSIS

are

surface

as ragged

or in groups.

METALLURGICAL

rupture

5.

CHARACTERISTICS

surface.

Occur

cracks

Castings

particle

should material

PENETRANT

be used

can

detect

near

for

final

analysis.

not removed

TESTING

prior

surface

to testing

will

hot tears,

cause

an invalid

METHOD

(1)

Liquid

penetrant

is recommended

(2)

Liquid

penetrant

is confined

for nonferrous

to surface

evaluation.

cast

material.

(3}

The

use

ing

%J (4)

the

of penetrants porous

Repeatability

tears. not

EDDY

e,

tears. not

A

C

TESTING

Discontinuities lend

CURRENT

TESTING

TYPICAL

CLOSE-UP

themselves

structure to eddy

after

to apply a long

when

associated

period for

with

by

surface

saturatfinish.

of time.

detecting

cast

hot

structure

do

testing.

METHOD. along current

Not with

the

recommended

for

complex

configurations

D

Hot Tear

detecting

hot do

testing.

HOT TEARS IN FILLET

iN (A)

Figure 7-31.

a contaminant

recommended

HOT TEARS IN CASTING

OF HOT TEARS

as

ability

poor

Not

type

act

the be

METHOD.

to ultrasonic

Metallurgical

may

affect may

of this

themselves

lend

castings and

of indications

ULTRASONIC

d.

on

structure

CLOSE-UP

OF CASTING

OF HOT TEARS

IN (B)

Discontinuity 7-59

732

INTERGRANULAR

I.

CATEGORY.

2.

MATERIAL.

3.

DISCONTINUITY

Surface

or internal.

appear from

singly the

fact

the

Two

CHARACTERISTICS A series

very

little

corrosion (See

a.

b.

Figure

that

NDT a.

(2)

to intergranular

relieving

wiI1 result

PENETRANT

Liquid

is visible the

results

on the

grain

May surface.

boundaries

of

AND

is

the

that is prone to intergranuIar stainless steel.

treat

may

of these

create

the

conditions

in intergranular

TESTING

penetrant

are: cor-

susceptibility

coupled

with

to a cor-

attack.

LIMITATIONS METHOD

first

choice

due

to the

size

and location

of this

of discontinuity.

Chemical

cleaning

operations may

Cleaning in solvents corrosion.

(4) Trapped b.

Either

APPLICATION

liquid penetrant test results. (3)

pattern.

corrosion

following

corrosion

or heat

corrosion.

atmosphere

type

product

direction

structure of the material as unstabilized 300 series

METHODS

(i)

of tntergranular

or corrosion in any

no definite

7-32.)

stress

LIQUID

nature

with

ANALYSIS

Metallurgical rosion such

rosive

insidious

extend

contribute

Improper

micro-openings

corrosion

may

intergranular

5.

The

METALLURGICAL factors

of small

in groups.

that

material.

4.

Service Nonferrous

or

Intergranular

CORROSION

RADIOGRAPHIC

immediately

contaminate

the

may

chlorine

release

penetrant solution may TESTING

article

before and

the

application

seriously

and accelerate

affect

of the

intergranuIar

present a cleaning or removal

problem.

METHOD

(1) Intergranular corrosion in the more

advanced stages has been detected

with radiography. (2) Sensitivitylevels may prevent the detection of fine intergranular corrosion. (3) Radiography may not determine rosion will occur.

on which surface the Intergranu]ar corV

7-60

c.

d.

EDDY

CURRENT

(1)

Eddy

current

(2)

Tube

or pipe

(3)

Metallurgical indications.

ULTRASONIC equipment

e.

MAGNETIC

lend

structure

the

intergranular

the

use

for

g

of intergranular

to this

material

METHOD•

may

method

TESTING Type

used

intergranular

METHOD.

of NDT

seriously

Not normally

to detect

corrosion.

screening

readily

of the

capability

of magnetic

the

themselves

PARTICLES

ing

METHOD

can be used

TESTING has

:

f-

TESTING

affect

although

corrosion. testing. the

output

the

corrosion. Not

of discontinuity

recommended

for

and material

restrict

detect-

particles.

.i

_-

.

"

"

.1

;% -j

A

MICROGRAPH SURFACE

OF INTERGRANULAR

FROM

SUBSURFACE

CORROSION

SHOWING

LIFTING

OF

CORROSION

#____

B

MICROGRAPH ONLY

Figure

7-32.

MINOR

SHOWING EVIDENCE

Intergranular

NATURE OF

OF INTERGRANULAR

CORROSION

Corrosion

IS EVIDENT

CORROSION. FROM

SURFACE

Discontinuity 7-61

V