Mahindra standard

STANDARD NO: G 00 0167 REVISION: C REFERENCE: SRN00281

TITLE: GRADE DESIGNATION FOR LOW CARBON COLD ROLLED STEEL SHEETS USED FOR AUTOMOTIVE APPLICATIONS DATE: 30–10–2007

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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 Cold rolled low carbon steel sheets and strips – specification. 3.2. JIS G 3141: 1977 Cold rolled carbon steel sheets and strips 3.3. JIS G 3135: 1986 Cold rolled high strength steel sheets with improved formability for

automobile structural use 3.4. DIN EN10 130 1991 Cold 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 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. REP: Rephosphorised 4.11. TS: Tensile strength 4.12. YS: Yield strength

5. REVISION HISTORY

5.1. Classification of series M21-M25 etc has been modified 5.2. Grades have been added in series M23-M25 5.3. Some grades have been removed from a series and put into other series 5.4. 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 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




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)

Constituent % Max. Permissible Variations for

Product Analysis over Specified Limit

MM GRADE

% C % Mn % S % P %C % Mn % S % P MM21 OA MM21 OS MM21 O8 MM21 O4 MM21 O2 MM21 O1

0.15 0.60 0.055 0.055

MM21 D 0.12 0.50 0.040 0.040 MM21 DD 0.10 0.45 0.035 0.035

MM22 EDD 0.08 0.40 0.030 0.030

0.02 0.03 0.005 0.005

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)

% Constituents (Max.) MM Grade

C Mn Si

Ceq Max.

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 - - - -




% Constituents (Max.) MM Grade

C Mn Si

Ceq Max.

MM23 IF300/400 - - - -

MM23 REP180/340 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 Table 3

Formability & High Strength Steels (M24 series) % Constituents (Max.)

MM Grade C Mn Si

Ceq Max

MM24 HSLA240 0.08 0.50 0.04 0.17 MM24 HSLA280 0.08 0.50 0.04 0.17 MM24 HSLA320 0.08 0.50 0.04 0.17 MM24 HSLA360 0.08 0.90 0.35 0.29 MM24 HSLA400 0.12 1.60 0.15 0.41

Table 4

Advanced High Strength Steels (M25 series) % Constituents (Max.)

MM Grade C Mn Si

Ceq Max

MM25 490Y - - - - MM25 540Y - - - - MM25 590Y - - - - MM25 DP260/450 0.08 1.6 0.40 0.41 MM25 DP300/500 0.14 1.6 0.40 0.47 MM25 DP320/600 0.14 1.5 0.40 0.46 MM25 DP340/590 - - - - MM25 DP400/780 - - - - MM25 DP450/780 0.15 2.2 0.60 0.62 MM25 DP550/980 0.2 2.0 0.40 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




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

Equivalent standards (For reference)

TS N/mm2

YS N/mm2

Thk of sheet % El Hardness

(HRB) r Internal Dia of Bend

MM21 OA IS 513 OA, JIS G3141SPCC A

275 min. 0.25 – 0.4

32 59 HRB Max. - Close

MM21 OS IS513 O SP JIS G3141 SPCCS

275 min. 0.4-0.6 34 65 HRB Max. - Close

MM21 O8 JIS G3141 SPCC8 294-412 0.6-1.0 36 50-71 HRB - Close

MM21 O4 IS513 O ¼H JISG3141 SPCC4

373-490 1.0- 1.6 37 65-80 HRB - 0.5t

MM21 O2 IS 513 O ½H JIS G3141 SPCC2

441-588 1.6- 2.5 38 74-89 HRB - 1t

MM21 O1 IS 513 O H JIS G3141 SPCC1

549 min.

N.A.

2.5 & Over

39 85 HRB Min. - No test

MM21 D IS 513 D 270-410 280 Max. 23** 65 HRB Max. - Close

MM21 DD IS 513 DD JISG 3141 SPCD

270-370 250 Max. 26** 57 HRB Max. 1.3 Close

MM22 EDD IS513 EDD JISG 3141SPCE

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,

MM22 IF05 may be assumed 140 N/mm2, whereas, for grade MM22 IF06 it may be assumed as 120 N/mm2

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)

MM grade Equivalent standards (For reference)

TS N/mm2

YS N/mm2 % El n r

MM23 IF180/340 - 340 min. 180-240 38 min 0.20 min. = 1.7 MM23 IF220/350 - 350 min. 220-260 36 min. 0.19 min. = 1.6 MM23 IF260/380 - 380 min. 260-300 32 min. 0.18 min. = 1.5




MM grade Equivalent standards (For reference)

TS N/mm2

YS N/mm2 % El n r

MM23 IF300/400 - 400 min. 300-400 30 min. 0.17 min. = 1.5 MM23 REP180/340 JIS3135 SPFC340 340 min. 180-260 36 min. 0.18 min. = 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. - -

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)

MM grade TS N/mm2 YS N/mm2 % 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. Table 8

Advanced High Strength Steels (M25 series)

MM grade Equivalent standards

(For reference) TS

N/mm2 YS

N/mm2 % El n Internal dia. of

bend

MM25 490Y JIS G 3135 SPFC 490Y 490 Min. 225 min. = 24* - close

MM25 540Y JIS G 3135 SPFC 540Y 540 Min. 245 min. = 21* - 0.5t

MM25 590Y JIS G 3135 SPFC 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 -




MM grade Equivalent standards

(For reference) TS

N/mm2 YS

N/mm2 % El n Internal dia. of

bend

MM25 DP340/590 JIS3135 SPFC590 = 590 340-500 = 16 - -

MM25 DP400/780 - = 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 - - 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 Base steel Resin thk (microns)

Typical application Service temp. (degree C)

MM30SDS80 All cold rolled grades

Polyacrylic-25 Dashboards, floors, body panels

-10 to 80

MM30SDS60 All cold rolled grades

Copolymer-25 Dashboards, floors, body panels

5 to 60

MM30SDS120 All cold rolled

grades Polyester-45 Dashboards, power train parts, distributor casings, rocker covers oil sumps,

20-120

MM30SDS150 All cold rolled

grades Polyacrylic-25

power train parts, oil sumps, distributor casings, rocker covers

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. For design purpose modulus of elasticity (E) may be assumed as 206,000 N/mm2 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

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