The development of railways,buildings and machineries has necessitated the implementation of stringent requirements for the materials of safe and light-weight structures,which can be achieved through the development of strong and tough advanced high strength steels (AHSS). AHSS are characterized by the combinations of multi-phase microstructures achieved through innovative process designs to meet the performance requirements of modern industries. Currently,the third generation AHSS,which include transformation-induced plasticity (TRIP)steel, quenching and partitioning (Q&P)steel,medium Mn steel,and carbide-free bainitic steel,are considered promising candidates for lightweight structural applications,because they possess the ability to induce combinations of excellent mechanical properties. In this paper,firstly we review recent studies on alloying designs,solid-state phase transformations,microstructure adjustments of the third generation AHSS,in particular,the roles of advanced heat treatments,and partitioning of alloying elements in microstructure transformations. AHSS comprise microstructures of mar-tensite,bainite,ferrite,and retained austenite. The amount and stability of retained austenite are crucial factors affecting the mechanical performance of AHSS. Secondly,the factors affecting the stability of retained austenite and the effect of austenite retention on strength,ductility, toughness,and fatigue properties are discussed. This paper would provide a reference to future research on obtaining a specific volume of metastable retained austenite in multiphase microstructures and exploring the relationship between microstructures and mechanical properties. Finally, the development trend of AHSS is briefly introduced for exploring new methods to improve the mechanical properties of metals. © 2023 Cailiao Daobaoshe/ Materials Review. All rights reserved.
