This specification covers the requirements for low carbon continuous cast steel for exposed and unexposed applications and is applicable to all low carbon steel sheet products and coated substrates. 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 rolled flat products with the appropriate surface type and surface finish are suitable for the application of surface coatings (metallic plating by melt dipping or thermal spray painting, electrolytic plating, organic coating and/or other coatings). This specification does not apply to steel for case hardening or strip applications. Additional requirements or agreements shall be specified by regional GM Automotive Operations (GM) business units, e.g., North America (GMNA), Europe (GME), Latin America, Africa, Middle East (GMLAAM), and Asia Pacific (GMAP).
Material Description. The material designation is defined by the General Motors Worldwide (GMW) base metal specification number, steel product type and steel grade. The steel product type is designated by "CR" for cold rolled products, or "HR" for hot rolled products. A numeral (1, 2, 3, etc.) will designate the steel grade formability level. The steel grade will correspond to the chemical and mechanical requirements as shown in Table 1, Table 2, and Table 3. A third suffix (C) may be added after the steel grade to designate a low carbon steelmaking practice. The finish type, an 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. 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 Section 8.
Typical Applications. Sheet metal parts consisting of low carbon steel products and coated low carbon steel substrates.