The Role of Transformation-Induced Plasticity in the Development of Advanced High Strength Steels

Lightweight structural components made of advanced high-strength steels (AHSSs) in the automotive industry can substantially reduce greenhouse gas emissions. The 3rd-generation AHSSs, which consist of medium Mn steel, quenching and partitioning (Q&P) steel, and carbide-free bainitic (CFB) steel, is the current research focus of the steel community. In particular, the retained austenite grains are the intrinsic components of the 3rd-generation AHSSs. These retained austenite grains can demonstrate a transformation-induced plasticity (TRIP) effect by transforming into martensite during mechanical loading, improving the strain-hardening behavior of AHSSs. Consequently, intensive research has been carried out over the past 30 years to understand the role of the TRIP effect on the development of AHSSs. Therefore, this review article is aimed to provide a state-of-the-art summary of recent progress on AHSSs with the TRIP effect. Specifically, the processing, the relationship between microstructure and mechanical properties, and the potential industrial applications of TRIP-enabled AHSSs will be addressed in this review. More importantly, the mechanical stability of the retained austenite grains, which determines the overall performance of the TRIP effect in AHSSs, will be discussed by considering several governing factors.