Mahindra standard

TITLE: GRADE DESIGNATION FOR FO R LOW LOW CARBON COLD ROLLED STEEL SHEETS USED FOR AUTOMOTIVE APPLICATIONS

STANDARD NO: G 00 0167 REVISION: C REFERENCE: SRN00281 30–10–2007 DATE:

1. OBJECTIVES The objective of this standard is to define M&M grade designation for low carbon cold rolled steel sheet grades used for automotive application.

2. SCOPE This standard covers cold rolled steel sheets & strips grades of different formability & strength levels.

3. REFERENCES 3.1. IS 513: 1994 3.2. JIS G 3141: 1977 3.3. JIS G 3135: 1986

Cold rolled low carbon steel sheets and strips – specification. Cold rolled carbon steel sheets and strips Cold rolled high strength steel sheets with improved formability for automobile structural use 3.4. DIN EN10 EN10 130 1991 Cold Co ld rolled flat steel products for cold forming 3.5. MM –G000154 Guideline for selection of hot and cold rolled steel sheet selection

4. TERMINOLOGY 4.1.  r : Plastic strain ratio 4.2. % E: Percent elongation elongation 4.3. BH: Bake Hardenable; 4.4. CR: Cold rolled 4.5. D: Drawn, DD: Deep drawn, EDD: Extra Deep Drawn, O: Ordinary 4.6. DP: Dual phase; 4.7. GL: Gauge Length 4.8. HSLA: High Strength Low Alloy 4.9. IF: Interstitial free 4.10. 4.10. REP: Rephosphorised 4.11. TS: Tensile strength 4.12. YS: Yield strength

5. REVISION HISTORY 5.1. 5.2. 5.3. 5.4.

Classification of series M21-M25 M21- M25 etc has been modified Grades have been added in series series M23-M2 M23- M25 5 Some grades have been removed from a series and put into other series Sound deadening steels have been added in new series M30

6. OWNERSHIP For any clarification on this standard, refer to Materials Technology Group, R&D, Nashik. This standard shall not be modified without prior consultation with standards department, R&D, Nashik.

7. APPLICABLE APPLICABLE MANUFACTURING/ QUALITYSTANDARDS F00 0168: Quality specification for cold rolled steel sheets and strips

8. RECOMMANDATIONS The materials are recommended as in tables 5 – 9 (mechanical properties) with chemical composition specified in tables 1– 4 This document should not be reproduced in any form or by any means without written approval from Mahindra & Mahindra Ltd. (AS) Page 1 of 6

TITLE: GRADE DESIGNATION FOR LOW CARBON COLD ROLLED STEEL SHEETS USED FOR AUTOMOTIVE APPLICATIONS


9. DESIGNATION (HOW TO SPECIFY ON DRAWING) These grades are designated on drawing as “cold rolled steel sheet grade”

Example 1 CR steel sheet grade MM21DD as per G 00 0167 & Sheet quality as per F 00 0168 GRADE CODE STANDARD NUMBER MM21DD G 00 0167

CHEMICAL COMPOSITIONS Table 1 General Structural Steels (M21 series) and High Formability Steels (M22 Series) MM Constituent % Max. Permissible Variations for GRADE Product Analysis over Specified Limit %C % Mn %S %P %C % Mn %S %P MM21 OA MM21 OS MM21 O8 MM21 O4 MM21 O2 MM21 O1 MM21 D MM21 DD MM22 EDD

0.15

0.60

0.055

0.055 0.02

0.12 0.10 0.08

0.50 0.45 0.40

0.040 0.035 0.030

0.03

0.005

0.005

0.040 0.035 0.030

Note: 1. Permissible variation in case of product analysis from the limit specified is also given in Table 1 2. Steel of these grades can be supplied with the addition of micro-alloying elements like Boron, Titanium, Niobium and Vanadium. The micro-alloying elements should not exceed 0.2 % in ladle analysis. However, in case of Boron, the limit shall be 0.006 %. 3. The Nitrogen content of the steel shall not be more than 0.007 %. For Aluminium killed or Silicon-Aluminium killed, the Nitrogen contents shall not exceed 0.012 %. This has to be ensured by the manufacturer by occasional check analysis. 4. Grades MM22 EDD, MM22 IF05, MM22 IF06 shall be supplied in fully Aluminium killed condition only. 5. When the steel is Aluminium killed, the total Aluminium content shall not be less than 0.02 %. When the steel is Silicon killed, the Silicon contents shall not be less than 0.1 %. When the steel is Aluminium silicon killed, the Silicon content shall not be less than 0.03 % and total Aluminium content shall not be less than 0.01 %. Table 2 High Formability & Strength (M23 series) MM Grade

% Constituents (Max.)

Ceq Max.

C

Mn

Si

MM23 IF180/340

0.01

0.70

0.25

0.17

MM23 IF220/350

0.01

0.90

0.25

0.20

MM23 IF260/380

-

-

-

-

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% Constituents (Max.)

MM Grade

Ceq Max.

C

Mn

Si

-

-

-

-

MM23 REP180/34 0

0.05

0.70

0.50

0.25

MM23 REP220/340

0.06

0.70

0.50

0.26

MM23 REP260/380

0.08

0.70

0.50

0.28

MM23 REP300/400

0.10

0.70

0.50

0.30

MM23 BH140

0.04

0.70

0.50

0.24

MM23 BH160

0.04

0.70

0.50

0.24

MM23 BH180

0.04

0.70

0.50

0.24

MM23 BH220

0.06

0.70

0.5

0.26

MM23 BH260

0.08

0.70

0.50

0.28

MM23 BH300

0.10

0.70

0.50

0.30

MM23 IF300/400

Table 3 Formability & High Strength Steels (M24 series) % Constituents (Max.) MM Grade C Mn MM24 MM24 MM24 MM24 MM24

HSLA240 HSLA280 HSLA320 HSLA360 HSLA400

0.08 0.08 0.08 0.08 0.12

0.50 0.50 0.50 0.90 1.60

Table 4 Advanced High Strength Steels (M25 series) % Constituents (Max.) MM Grade C Mn MM25 490Y MM25 540Y MM25 590Y MM25 DP260/4 50 MM25 DP300/5 00 MM25 DP320/6 00 MM25 DP340/5 90 MM25 DP400/7 80 MM25 DP450/7 80 MM25 DP550/9 80

0.08 0.14 0.14 0.15 0.2

1.6 1.6 1.5 2.2 2.0

Si 0.04 0.04 0.04 0.35 0.15

Si 0.40 0.40 0.40 0.60 0.40

Ceq Max 0.17 0.17 0.17 0.29 0.41

Ceq Max 0.41 0.47 0.46 0.62 0.60

General Note: 1. Hazardous Chemical substances control: All products supplied for export vehicles to European countries , must comply with the requirement of the M&M std F000 387 2. Chemical composition is just for reference and it should not be treated as sole acceptance criteria for raw material. Mechanical properties, surface finish and dimensional tolerance plays important role in sheet metal forming; so these requirements are to be considered as mandatory for raw material. For pressed part This document should not be reproduced in any form or by any means without written approval from Mahindra & Mahindra Ltd. (AS) Page 3 of 6



chemical compositions as well as mechanical properties are not significant since the part is already formed. Hence surface finish and freedom from forming defects like cracks; wrinkles, localised thinning, etc. need to be given importance. The strength consideration of finished parts can be ascertained by hardness check like Vickers/Rockwell with suitable load. 3. Ladle analysis of material when carried out either by the method specified in the relevant part of IS 228 or any other established instrumental/chemical method, shall be as given in Table-1 and 2. In case of dispute, the procedure given in relevant part of IS 228 shall be referee method. MECHANICAL PROPERTIES Table 5 General Structural Steels (M21 series) and High Formability Steels (M22 Series) MM grade MM21 OA MM21 OS MM21 O8 MM21 O4 MM21 O2 MM21 O1 MM21 D

Equivalent standards (For reference) IS 513 OA, JIS G3141SPCC A IS513 O SP JIS G3141 SPCCS JIS G3141 SPCC8 IS513 O ¼H JISG3141 SPCC4 IS 513 O ½H JIS G3141 SPCC2 IS 513 O H JIS G3141 SPCC1 IS 513 D

IS 513 DD JISG 3141 SPCD IS513 EDD MM22 EDD JISG 3141SPCE MM21 DD

TS N/mm2

YS N/mm2

Thk of % El sheet

Hardness (HRB)

Internal r Dia of  Bend

275 min.

0.25 – 0.4

32

59 HRB Max.

-

Close

275 min.

0.4-0. 6

34

65 HRB Max.

-

Close

0.6-1. 0

36

50-71 HRB

-

Close

373-490

1.0- 1.6

37

65-80 HRB

-

0.5t

441-588

1.6- 2.5

38

74-89 HRB

-

1t

549 min.

2.5 & Over

39

85 HRB Min.

-

No test

294-412

N.A.

270-410 280 Max.

23**

65 HRB Max.

-

Close

270-370 250 Max.

26**

57 HRB Max.

1.3

Close

270-350 220 Max.

32**

50 HRB Max.

1.6

Close

MM22 IF05

EN10130 FeP05

270-330 180 Max.

40***

-

1.9

Close

MM22 IF06

EN10 130 Fe PO6

270-350 180 Max.

38***

-

1.8

Close

Note: 1. For design purpose lower limit of yield stress for grade MM21 D, MM21 DD, MM22 EDD, 2 MM22 IF05 may be assumed 140 N/mm , whereas, for grade MM22 IF06 it may be 2 assumed as 120 N/mm 2. In case of bend test, cracks shall not be generated on the external side of test specimen ** GL = 5.65 √ So Min. where So is the cross sectional area of the test piece. *** GL = 80 mm Table 6 High Formability & Strength (M23 series) Equivalent standards TS MM grade (For reference) N/mm2

YS N/mm2

% El

n

r 

MM23 IF180/340 MM23 IF220/350 MM23 IF260/380

180-240 220-260 260-300

38 min 36 min. 32 min.

0.20 min. 0.19 min. 0.18 min.

= 1.7 = 1.6 = 1.5

-

340 min. 350 min. 380 min.


TITLE: GRADE DESIGNATION FOR LOW CARBON COLD ROLLED STEEL SHEETS USED FOR AUTOMOTIVE APPLICATIONS Equivalent standards (For reference)


TS N/mm2

YS N/mm2

% El

n

r 

MM23 IF300/400 MM23 REP180/340 JIS3135 SPFC340

400 min. 340 min.

300-400 180-260

30 min. 36 min.

0.17 min. 0.18 min.

= 1.5 = 1.5

MM23 REP200/340 -

340 min.

200-300

32 min.

0.15 min.

= 1.5

MM23 REP220/340 JIS3135 SPFC370,

340-400

220-280

30 min.

0.16 min.

= 1.3

MM23 REP260/380 JIS3135 SPFC390

380-440

260-280

28 min.

-

-

MM23 REP300/400 IS3135 SPFC440

400-480

300-360

26 min.

-

-

MM grade

MM23 BH140

-

= 270

140-230*

40 min.

0.20 min.

= 1.5

MM23 BH160

-

280-350

160-210*

38 min.

0.17

1.9

MM23 BH180

-

= 300

180-250*

34 min.

0.17 min.

= 1.4

MM23 BH220

JIS3135 SPFC340H

340-400

220-270*

32 min.

0.16

1.5

MM23 BH260

-

370-420

260-310*

30 min.

0.15

-

MM23 BH300

-

420-480

300-360*

28 min.

0.14

-

Note: Bake Hardenable (BH) steels offers a combination of good formability in incoming steel and high yield strength in the final formed part which is generally not possible in conventional highs strength steels. Generally there is an increase of yield strength after forming by 20-40 MPa and another 30-40 MPa after baking hence final yield strength of steel is generally 50-80 MPa higher than incoming steel. General applications of BH grade steel are in doors, deck lead, quarter panels, fenders, hoods & roofs. These steels can also be used in vehicle weight reduction through downgaging. Table 7 Formability & High Strength Steels (M24 series) TS N/mm2

YS N/mm 2

% El

MM24 HSLA280

380-440

280-340

28 min.

MM24 HSLA320

410-480

320-380

24 min.

MM24 HSLA340

440-500

340-360

22 min.

MM24 HSLA360

450-520

360-430

20 min.

MM24 HSLA400

460-590

400-500

18 min.

MM grade

Table 8 Advanced High Strength Steels (M25 series) MM grade

Equivalent standards (For reference)

TS 2 N/mm

YS 2 N/mm

% El

n

Internal dia. of bend

MM25 490Y

JIS G 3135 SPFC 490Y

490 Min.

225 min.

= 24*

-

clos e

MM25 540Y


540 Min.

245 min.

= 21*

-

0.5t

MM25 590Y


590 Min.

265 min.

= 18*

-

1t

MM25 DP260/450

-

450-300

260-350

= 28

0.16

-

MM25 DP300/500

JIS3135 SPFC490

500-580

300-380

= 26

0.15

-

MM25 DP320/600

JIS3135 SPFC540

600-700

320-400

= 22

0.15

-




Equivalent standards (For reference)

TS 2 N/mm

YS 2 N/mm

% El

n

Internal dia. of bend

MM25 DP340/590

JIS3135 SPFC590

= 590

340-500

= 16

-

-

MM25 DP400/78 0

-

= 780

400-590

= 12

-

-

MM25 DP450/780

JIS SPFC780Y

780-900

450-550

= 16

0.10

-

MM25 DP550/980

JIS SPFC980Y

980-1100

550-700

= 10

-

-

MM grade

Note: Dual phase steels have high initial work hardening coefficient (n) which will distribute plastic strain and improves uniform elongation. Dual phase steels also have significant advantage in energy absorption during crash. Table 9 Sound Deadening steel (M30 Series) MM Grade MM30SDS80 MM30SDS60

Base steel All cold rolled grades All cold rolled grades

Resin thk (microns) Polyacrylic-25 Copolymer-25

MM30SDS120

All cold rolled grades

Polyester-45

MM30SDS150

All cold rolled grades

Polyacrylic-25

Typical application Dashboards, floors, body panels Dashboards, floors, body panels Dashboards, power train parts, distributor casings, rocker covers oil sumps, power train parts, oil sumps, distributor casings, rocker covers

Service temp. (degree C) -10 to 80 5 to 60 20-120

40-150

Note: Sound deadening grades sheets can be produced in all the cold rolled steels, bare or coated .The different qualities (i.e. high strength v/s draw ability can be employed). The thickness of the two facing sheets can be different. The resin core is 25 or 45 micron. General Notes: 1. The value of plastic strain ratio ( r ) is only applicable to products of thickness equal to or greater than 0.5 mm. When the thickness is over 2 mm the value of  r is reduced by 0.2. 2 2. For design purpose modulus of elasticity (E) may be assumed as 206,000 N/mm and Poisson’s ratio may be assumed as 0.3 for all grades 3. Unless otherwise specified gauge length for arriving at % elongation is 50mm. SUPERSEDES M&M Standard M 6504


Mahindra standard

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