4-Vickers Hardness Test (1)

EXPERIMENT NO:4 AIM:

 To perform Vickers Hardness Hardness Test & determine Vickers Vickers hardness number of the given specimen. APPARATUS:

Vickers Hardness testing Machine, Diamond indenter in the shape of right pyramid with square base and an ange of !"# degree , specimen bar of cast iron, brass, H$$. auminum. % diamond indenter in the form of right pyramid with square base & with specified specified ange between apposite face at vorte is forced into the surface of test piece foowed by measurement of diagona ength of the indenter eft in surface s urface after remova of the oad. PRINCIPLE:

FOEMULA:

 The %verage of two diagonas is used in in the foowing formua to find Vickers Hardness 'umber V(') !.*+(- d /here d) 0ength of diagona of square impression in mm () %ppied oad in 1g THEORY 2

The Vickers Hardness Test was deveoped in 3ngand in !45 by $mith & $andand at Vickers 0td. The Vickers Test two distinct force range, micro 6!7g to !777g8 and macro 6!1g to !571g8, to cover a testing requirement. The indentor is same for both ranges.

PROCEDURE:

!. $urface $urface of which hardness hardness is to be measur measured ed is to be made smooth smooth and free from oide, dirt and defect because the impression is very sma. 5. The surface surface on which which impressio impression n is to be measured measured shoud shoud be parae to the bottom surface, and perpendicuar to oading ais and paced on rigid support ". 9ring 9ring pyramida pyramida diamond diamond indenter indenter into contact contact with test test surface surface in such way that cear image of specimen is pro:ected on screen. +. %ppy test test force in directi direction on perpendicu perpendicuar ar to surface, surface, without without shock or vibration by bringing the ever into the oading condition unti appied force attains specified vaue . The duration duration test test force force shoud shoud be be !7;!se !7;!sec. c.

1 MSS/SEMS/META LAB/EXPT NO-3

#. %fter time is compete, bring the ever into unoading condition and indenter removed eaving sampe that appears square shaped on surface. <. The indentation is pro:ected at magnified scae on focusing screen and depth of two diagonas of square indentation is measured. The arithmetica mean of diagona shoud be taken for cacuation of Vickers Hardness 'umber.

ADVANTAGES:

!. % wide range of test forces avaiabe to suit every appication.. 5. More accurate readings can be taken. ". $ince diamond indenter is used it does not get deform during testing hard materia

DISADVANTAGES:

!. The test demand good poish on surface thus more time is required. 5. The test is sow and sub:ected to persona error if measurements are not taken propery . PRECAUTIONS:

!.

The surface of specimen shoud be smooth highy poished and free from defects because impressions created very sma. 5. The thickness of specimen shoud be !. times diagona of impression at ast. ". 9oth top and bottom surface shoud be parae and perpendicuar to oading ais.

OBSERVATION TABLE:

$ = ' o

$pecim en

0oad %ppie d 6(8

0ength of one Diagona6 d8

0ength of Mean other 0engt Diagona6 h d8

Hardnes s 9y >acuati on

Hardne ss 9y >hart

! 5 " RESULT:

 The Vickers Hardness 'umber of given specimen is 2 MSS/SEMS/META LAB/EXPT NO-3

!; 5; ";

CONCLUSION:

 The vaue of Vickers Hardness 'umber by cacuating & by chart is very cose.

VICKERS HARDNESS TEST

3 MSS/SEMS/META LAB/EXPT NO-3