Third Generation 980 Class AHSS: A Viable Alternative to Replace Press-Hardenable Steels (PHS) in Automotive Rear Rail Applications 2020-01-0534

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.