A comprehensive overview of high strength and toughness steels for automobile based on QP process

High-strength steels support the rapid development of modern automobile industry. Especially quenching-partitioning (QP) steels have presented the considerable potential thanks to their excellent mechanical properties. In recent years, quenching-partitioning-tempering (QPT), as well as other processes developed from QP process (DF-QP processes), have received much attention. Numerous QP and QPT steels have been widely used in automobile body materials. This paper summarizes the design principles of QP, QPT, and DF-QP processes of the latest research progress on microstructures and mechanical properties of the high-strength and toughness steels. Furthermore, three key aspects, involving of (i) the carbon (C) partitioning behavior during heat-treatment process and its influence on austenite stability, (ii) the internal relationship between austenite stability and deformation mechanism, and (iii) the influence of micro-alloying elements on microstructure, are summarized in the QPT steels. Finally, the service performances of above-mentioned steels are evaluated and their development prospects are forecasted.