Variable Thickness Rolled Blanks (VTRB) and Tubes (VTRT) Fabricated from Sheet Steel
|Publication Date:||1 June 2019|
This standard defines the requirements for variable thickness rolled blanks (VTRB) and tubes (VTRT) used in the manufacture of automotive steel parts. This material is produced from continuous cast hot or cold rolled coils/strip that will subsequently be cold rolled to specific multiple thicknesses, annealed or as-rolled, and galvanized (if applicable), and then leveled and cut to specified blank sizes to produce a finished part. Variable thickness rolled blank products shall be used for cold formed stampings and hot formed stampings. Variable thickness rolled tubes shall be manufactured from variable thickness rolled blanks that are formed into circular tubes along the longitudinal direction and joined by a laser-welded seam.
Material Description. The material designation is specifically used for variable thickness material defined by the thickness values, GMW base metal specification number, steel product type, minimum yield and/or tensile strength, coating (if applicable) and finish type. The steel product type is designated by either Cold Rolled (CR) minimum yield strength for High Strength Low Alloy (HSLA) grades from GMW3032M-ST-S or minimum tensile strength/yield strength for Hot Stamped (HS) (or Hot Stamped Tube (HT)) grades from GMW14400M-ST-S. Applications of variable thickness rolled blanks shall be limited to unexposed parts.
Material Call-Outs. The list of material and coating designations shown in Table 1 are the only approved material call-outs that can be released unless Materials Engineering and the appropriate Global Sub-System Leadership Team approves.