With the increasing of atmospheric environmental problems and the global energy crisis, energy conservation and emission reduction will remain a global theme in the coming decades. The automotive industry is required to reduce body weight without reducing safety in order to achieve the goal of energy saving and emission reduction. The lightweight of automobiles has promoted the development of advanced high-strength steel from the first generation to the third generation today. Advanced high-strength steel is mainly through the combination of alloy composition design, hot rolling, cold rolling, heat treatment and other processes to adjust its microstructure to achieve lightweight and safety, and its internal deformation mechanism research is more helpful to grasp the performance control process. The disadvantages of the first and second generation automobile steels mainly include the following two aspects: On the one hand, the main use of ferrite and other soft phases as the matrix leads to poor comprehensive mechanical properties, making it difficult to achieve true weight reduction; on the other hand, the second the improvement of the performance of the automotive steel is at the expense of the addition of a large number of alloying elements, which increases the production cost, and it is difficult to finely control the casting and heat treatment processes in the commercial production, and there are many disadvantages. Therefore, the third-generation automotive steel has achieved sound development, and its comprehensive mechanical properties have filled the gap between the first and second-generation automotive steels. As a typical representative, Q&P steel uses the quenching-partitioning process to finely control the multi-phase, metastable and multi-scale microstructure, and obtain a mixed structure of martensite, ferrite and austenite. Compared with the second generation, the third generation automobile steel has a lower alloying element content, which meets the requirements of reducing costs. The hybrid structure of FCC and BCC brings the characteristics of high-strength plastic product (tensile strength × elongation), which makes the performance of the third-generation automobile steel close to the target level of the times. This article summarizes the development history of new Q&P steels for automobiles, introduces the role of alloying elements, springback during forming, and explains the internal principles of process optimization according to the order of heat treatment process parameters (heating temperature, quenching temperature, distribution temperature, distribution time). Summarized the toughness mechanism of plastic deformation-"four effects, two mechanisms", considered the importance of dynamic mechanical properties to practical engineering applications, and put forward new Q&P steel strengthening recommendations based on major research results-grain boundary phase transformation strengthen. Finally, it describes the problems facing the current development and looks forward to the field. © 2021, Materials Review Magazine. All right reserved.
