GMW3032 |
This standard covers the requirements for continuous cast sheet
steel with specified minimum yield strengths from 180 MPa through
700 MPa and is applicable to uncoated and coated, cold (CR) or hot
rolled (HR) low carbon, solid solution strengthened,
bake-hardenable (BH), and interstitial free (IF) or high strength
low alloy (HSLA) substrates with good formability. Continuously hot
or cold rolled flat products shall be supplied as coils or sheet.
Hot rolled flat products are usually supplied in thicknesses
1.75 mm. These flat products are used for cold forming and for
manufacturing of welded tubes. Cold or hot rolled flat products
with the appropriate surface type and surface finish are suitable
for the application of surface coatings (metallic hot dipping,
electrolytic plating, hot spray painting, organic coatings and/or
other coatings). This specification does not apply to steel for
case hardening and cold reduced, work hardened strips. Additional
requirements or agreements shall be specified by regional GM
business units, e.g., North America (GMNA), Europe (GME), Latin
America (GMLAAM), and Asia Pacific (GMAP).
Material Description. The material designation
is defined by the GMW base metal specification number, steel
product type, minimum yield strength, and finish type. The steel
product type is designated by CR for cold rolled products, or HR
for hot rolled products. Microstructure free of banding, which is
caused by the interdendritic segregation of manganese during
solidification, is specified for hot rolled HSLA
inclusioncontrolled grades that are used for chassis
applications.
A numeral (180, 210, 240, etc.) will designate the minimum yield
strength level in MPa (Mega-Pascals). A designation of steel type
shall be added to bake hardenable (B2), solid solution strengthened
grades (P and IF), structural automotive (SA) and high strength low
alloy (LA) steels as shown in paragraph 8. An "F" designation may
be added on engineering and/or manufacturing documents following an
LA steel type to specify the steel as inclusion-controlled. A "B"
designation is specified for hot rolled LAF type grades which need
to be free of microstructural banding. The steel grades will
correspond to the chemical and mechanical requirements as shown in
Tables 1 thru 5. The finish type, Pan alpha character, will
designate the finish as E (exposed) or U (unexposed). In addition,
products which are not coated shall have the word "UNCOATED" added
to the call-out after the steel type, but before the finish
designation. A special requirement for temper rolling may be
required and shall be specified with a "T" designation. The above
descriptive items are used together to form the coding system.
Examples of the coding system for engineering part drawings and
manufacturing engineering documents are shown in paragraph
8.
Material Identification. See Appendix
A.
Symbols. Not applicable.
Typical Applications. Typical applications are
coated or uncoated sheet metal parts consisting of high strength
sheet steel with specified minimum yield strengths from 180 MPa
through 700 MPa.
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