Advanced High-Strength Sheet Steels for Automotive Applications

Automotive light-weighting efforts have resulted in the development and implementation of a variety of so-called advanced high-strength steels (AHSS). These AHSS exhibit superior strength and ductility/formability as compared to mild steels or high-strength fully martensitic steels. A variety of microstructural concepts and associated alloying and processing routes have been pursued in AHSS development to include dual-phase, transformation-induced plasticity (TRIP), bainitic- and TRIP-aided bainitic ferritic, quenching and partitioning steels, etc. This chapter will review these various concepts along with press-hardening, a process where forming is done at high temperature in the austenitic phase field and final strength is set by quenching following forming to obtain a high-strength martensitic microstructure.