Third Generation 980 Class AHSS: A Viable Alternative to Replace Press-Hardenable Steels (PHS) in Automotive Rear Rail Applications

Commercially available Third Generation Advanced High Strength Steels (GEN3 AHSS) are qualified by automakers worldwide. With an excellent combination of strength and ductility, GEN3 AHSS are cold-formable and have shown potential to replace press hardenable steels (PHS) in structural applications. With overall formability equivalent to 590DP, U. S. Steel 980 GEN3 AHSS (980 XG3™ AHSS) may achieve cold-formed component geometries similar to those achieved by hot-formed PHS. Furthermore 980 GEN3 AHSS demonstrates a substantial increase in post-forming yield strength due to the combined effects of work-hardening and bake-hardening-thereby contributing strongly toward crash energy management performance. The technical challenges and attributes of cold-formed 980 GEN3 AHSS are explored in this paper for an automotive rear rail application (currently PHS), including: formability analysis, wrinkling elimination and springback compensation. A successful rear rail stamping trial was run with EG-coated 980 GEN3 AHSS. In computer simulations of rear-end crash events, 980 GEN3 AHSS and PHS showed equivalent performance at the same thickness. Physical rear end crash tests proved the same.