1、 WORLDWIDE ENGINEERING STANDARDS Material Specification GMW14400 Pre-Coated or Uncoated Low Carbon, Heat-Treatable Boron Steel Copyright 2012 General Motors Company All Rights Reserved May 2012 Originating Department: North American Engineering Standards Page 1 of 18 1 Scope This specification cover
2、s the requirements for low carbon, heat-treatable boron steel used in the manufacture of structural parts to manage very high tensile loads without significant deformation such as required in safety and occupant protection. This material is heat treated and then formed and simultaneously quenched in
3、 a water-cooled die in a process referred to as hot stamping, hot press forming or press hardening. Material produced by this process generally referred to as press hardened steel (PHS). This process results in a part with a microstructure consisting of essentially 100% tempered martensite or marten
4、site with trace amounts of bainite. Note: For bonded applications with pre-coated press hardened steel, the material shall meet additional coating adhesion requirements in 3.2.7 and adhesive compatibility requirements in 3.3.2. 1.1 Material Description. The material designation is defined by the GMW
5、 material specification number, material category (Sheet or Tubular product), steel product type, grade, and finish type. The substrates used in these applications may be cold rolled or hot rolled, but the product type is designated as heat treated (HT) or hot stamped (HS), as appropriate. The steel
6、 grades will correspond to the chemical and mechanical requirements as shown in Table 2 and Table A1 through Table A3. The surface quality, represented as an alpha character, shall be designated with the surface quality. Only the surface quality designation of U, representing an unexposed applicatio
7、n, shall be used unless otherwise approved by Materials Engineering. The above descriptive items are used together to form the coding system. Examples of the coding system for engineering part drawings, electronic math data files and/or manufacturing engineering documents are shown in Section 8. 1.1
8、.1 Resistance Welded Mechanical Tubing. Tubes supplied to this specification are roll formed from a steel strip to the desired shape and dimension, electrical resistance welded into a tube, and then heat treated to achieve the final mechanical property requirements. 1.1.2 Induction Heat Treated Stee
9、l. Part sections formed with this operation and supplied under this standard shall be made by stamping in the as-rolled condition. The raw stamping can be selectively coil induction hardened to achieve the required strength requirements. Al-Si, Zn, Zn-Fe, or Zn-Ni pre-coated products shall not be us
10、ed in these applications. 1.1.3 Hot Stamped Die Quenched Steel. Parts shall be made by austenitizing a pre-cut blank, hot stamping the heated blank and rapid cooling (quenching) the stamped part in the die or via water quenching. Press hardened steel (PHS) can be formed by either direct or indirect
11、stamping processes. The direct process is considered as main-stream for all usages (except tubes). The indirect process is less common and more expensive since it requires two dies and is not compatible with common oven designs and press systems. Note: Since the indirect stamping process is not glob
12、ally available, the indirect process must not be used (or parts designed to require its use) without the prior authorization of the Global Functional Lead (GFL). Use of the indirect process implies that effected part cannot be used globally without driving excessive cost to ship stamped parts global
13、ly. Exception: The indirect process is globally available and can be used without prior approval only for tubular products such as axle tubes. 1.1.3.1 Uncoated Products. Parts formed with uncoated steel and supplied under this standard shall be subsequently blasted to remove oxide from the surface a
14、s described in section 3.3.3.2. 1.1.3.2 Pre-Coated Products. Parts formed with a hot stamping operation may also utilize pre-coated steels furnished according to this specification in order to eliminate the need for blasting and/or improve corrosion performance. Copyright General Motors Company Prov
15、ided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14400 Copyright 2012 General Motors Company All Rights Reserved May 2012 Page 2 of 18 Aluminum-Silicon (Al-Si) Pre-Coatings: A
16、l-Si coated parts shall not be cold-stamped prior to the hot stamping operation, but slight roll-forming operations may be allowable if the coating is not damaged. Blasting is not permitted for Al-Si pre-coated parts to prevent damage of the coating. Zinc Based Pre-Coatings: Parts are preferably sta
17、mped by the direct hot stamping process. After hot forming and cooling, parts shall be blasted to remove any oxide layer from the surface as described in section 3.3.3.2. 1.1.4 Material Call-Outs. The list of material and coating designations shown in Table 1 are the only approved material call-outs
18、 that can be released unless Materials Engineering and the appropriate Global Subsystem Leadership Team approves. Table 1: Approved Material Call-Outs Material Call-out Coating System Material Description GMW14400M-ST-S-HS1300T/950Y-MS-UNCOATED-U Uncoated Uncoated press hardened steel stampings GMW1
19、4400M-ST-S-HT1475T/1170Y-MS-UNCOATED-U Uncoated Uncoated induction heat treated products GMW14400M-ST-T-HT1475T/1170Y-MS-UNCOATED-U Uncoated Uncoated welded and heat treatable tubular products GMW14400M-ST-S-HS1300T/950Y-MS-AS60G60G-U AlSi Al-Si coated press hardened steel stampings GMW14400M-ST-S-H
20、S1300T/950Y-MS-AS40G40G-U AlSi Al-Si coated press hardened steel stampings GMW14400M-ST-S-HT1475T/1170Y-MS-AS60G60G-U AlSi Al-Si coated induction heat treated products GMW14400M-ST-T-HT1475T/1170Y-MS-AS60G60G-U AlSi Al-Si coated welded and heat treatable tubular products 1.2 Symbols. Not applicable.
21、 1.3 Typical Applications. Typical applications are uncoated or pre-coated sheet metal stampings and thin gauge tubular structural parts requiring tensile strengths exceeding 1300 MPa and 500 MPa respectively. Typical applications include door impact beams, bumper impact beams, and structural reinfo
22、rcements for side impact and roof strength. 1.4 Remarks. See Table B1 in Appendix B for cross-referenced/superseded specifications. 2 References Note: Only the latest approved standards are applicable unless otherwise specified. 2.1 External Standards/Specifications. ASTM A370 ASTM E1077 ISO 6892 JI
23、S Z2201 ASTM A428 EN 10247 ISO 7438 SAE J419 ASTM A513 EN 10346 ISO 10275 SEP 1160 ASTM A751 ISO 898-1 ISO 18594 ASTM E45 ISO 4287 ISO/TS 16949 2.2 GM Standards/Specifications. GMW8 GMW3335 GMW14729 GMW15282 GMW3011 GMW14019 GMW14829 GMW16549 GMW3059 GMW14700 GMW14872 GMW16579 GMW3224 GMW14704 GMW15
24、200 2.3 Additional References. Best Practice BODYSTR-33. The supplier shall work with the GM responsible engineer to comprehend this requirement. GWS-5A (available at ). Statement of Requirements (SOR) Appendix N. TMC003 Material Safety Data Sheet guidance documents (available at ). Copyright Genera
25、l Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14400 Copyright 2012 General Motors Company All Rights Reserved May 2012 Page 3 of 18 3 Requirements The
26、following section defines specific requirements for material on delivery, processing, performance and other stages during life cycle. Deviations required for individual GM business units are listed in the Deviations at the end of this document. Parts supplied according to this specification shall un
27、dergo successful trials that fully meet end product requirements. In the event of any changes to the heat treatment and/or manufacturing process to which the part was successfully validated, the appropriate engineering group must be notified and the part must be tested and re-qualified to the proper
28、 Production Part Approval Process (PPAP) level as determined by GM. Hot stampers are required to maintain a consistent source of steel supply and to use GM approved suppliers listed in GMs MATSPC system. 3.1 Requirements on Test Specimens. Not applicable. 3.2. Engineering Requirements. 3.2.1 Chemist
29、ry. Base metal composition based on product (coil, or sheet/blanks) analysis determined per ASTM A751 shall conform to the requirements of Table 2 and/or shall be agreed upon between supplier and purchaser. When end product (coil/blank) test results are not available, ladle analysis may be used. Che
30、mical composition on the end product is the referee method. Table 2: Chemical Composition, Mass % Note 1 Press Hardened Steel Carbon 0.19% to 0.27% Manganese 1.00% to 1.50% Aluminum 0.010% Silicon 0.50% Phosphorous 0.030% Sulfur 0.005% Chromium 0.35% Titanium 0.020% to 0.055% Nitrogen 0.010% Boron 0
31、.0005% to 0.004% Note 1: See Table D1 in the deviations section for high hardenability alloy chemistry. 3.2.2 Surface Lubrication. Steel supplied to this specification shall be coated with a designated lubricant (e.g., mill oil or pre-lube) and comply with GMW14019. Requirements for lubrication of p
32、ost hot stamped parts are included in paragraph 3.3.3.2. 3.2.3 Mechanical Property Requirements. The 0.2% Offset Yield Strength, Tensile Strength and Percent Total Elongation shall be determined in the longitudinal direction per GMW3335 for cold-formed parts. The test direction is not critical for f
33、inished, hot-formed parts. Tests shall be performed using samples per ISO 6892 Type I (50 mm gage length ASTM type sample), ISO 6892 Type II (80 mm gage length DIN type sample), or JIS Z2201 (No. 5). When specified for cold stamped applications, the strain hardening exponent n value shall be determi
34、ned per ISO 10275. The specific strain level shall be reported with all test results. The strain hardening exponent n value shall be determined at 10% to 20% strain, or at 10% to end of uniform elongation when uniform elongation is 99.9% per GMW8 64 to 93 55 to 105 9 to 13 Indirect Hot Stamp Followi
35、ng heat treatment N/A N/A 15 to 30 HD50G50G-U GMW14400M-ST-S-HS1300T/950Y-MS-HD50G50G-U Prior to heat treatment Zinc: 99.9% per GMW8 50 to 65 45 to 75 7 to 9 Direct or Indirect Hot Stamp Following heat treatment N/A N/A 14 to 22 Zn-Fe Pre-Coated HD80A80A-U GMW14400M-ST-S-HS1300T/950Y-MS-HD80A80A-U P
36、rior to hot-stamping Zinc: 87 to 92 80 to 95 70 to 105 11 to 14 Direct Hot Stamp Following heat treatment N/A N/A 19 to 26 HD65A65A-U GMW14400M-ST-S-HS1300T/950Y-MS-HD65A65A-U Prior to hot-stamping Zinc: 87 to 92 65 to 95 55 to 105 9 to 13 Direct Hot Stamp Following heat treatment 15 to 25 Zn-Ni Pre
37、-Coated EG60N60N-U GMW14400M-ST-S-HS1300T/950Y-MS-EG60N60N-U Prior to hot-stamping Zinc: 88.5% to 90.5% Nickel: 9.5% to 11.5% 60 to 88 50 to 100 8 to 12 Direct Hot Stamp Following hot-stamping N/A 15 to 25 Note 1: Additional demands can be specified by the local business units. Note 2: Prior to hot-
38、stamping, suitable evaluation instruments to measure coating thickness on the as-received sheet include eddy current, ferromagnetic, or microscopy. Magnetic inductive measurements are not recommended following the hot-stamping operation without proper calibration. Copyright General Motors Company Pr
39、ovided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14400 Copyright 2012 General Motors Company All Rights Reserved May 2012 Page 18 of 18 Deviations Requirements for Local Bus
40、iness Units Dev 3.2 Requirements on Delivery. Dev 3.2.1 Chemical Requirements. An alternate base material chemistry may be used by local business units as shown in Table D1. The use of the alternative chemistry must be reviewed and approved by Materials Engineering and the responsible GSSLT and shal
41、l include a part specific global strategy if used on parts manufactured in multiple regions. Table D1: Chemical Composition of High Hardenability Alloy High Hardenability Press Hardened Steel Carbon 0.19% to 0.27% Manganese 1.50% to 2.50% Aluminum 0.010% Silicon 0.50% Phosphorous 0.030% Sulfur 0.005
42、% Chromium 0.35% Titanium 0.020% to 0.055% Nitrogen 0.020% Boron 0.0005% to 0.004% Dev 3.2.1.1 Base Metal. GM-Asia Pacific and GM-Europe: Steel products shall have chemical composition that is agreed between purchaser and supplier that is capable of achieving the desired mechanical properties specif
43、ied in GMW14400. Chemistries not meeting Table 1 requirements shall be reviewed by Advanced Technology - Welding Group at for approval. Dev 3.2.2 Mechanical Requirements. GM-Asia Pacific: Australian and Japanese Steel Suppliers for Holden shall perform tensile testing to Japanese Industrial Standar
44、d JIS Z2201 (No. 5 test piece), respectively. GM-Europe: All specified values must be met in the longitudinal (L) direction. Axle tubes may be specified with the following final part requirements: GMW14400M-ST-T-HT1200T/950Y-MS YS: 950 MPa to 1050 MPa TS: 1200 MPa minimum A5: 6% minimum Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
