Research progress on DP steel for automobiles

Abstract

With the excellent mechanical properties, such as continuous yielding behavior, low yield point, and high work hardening rate, DP steel has been concerned by major automobile manufacturing companies and been used widely in the modern automobile industry. DP steel, which is manufactured into vehicle body structure, not only can reduce mass and fuel consumption, but also can increase the ability of resisting depression. The strength as well as the fatigue property of vehicle suspension system and vehicle steel can increase significantly due to DP steel. Main alloying elements addition can ensure the stability of the dual phase that is consisted of the martensite and the ferrite, trace alloying elements addition can refine microstructure and improve the mechanical properties. Production process of hot rolled DP steel involves low-temperature curing process and medium-temperature curing process, cold rolled DP steel mainly relies on continuous-annealing process. The design of curling process is based on the control of the rolling temperature and cooling rates; anneal temperature and over aging temperature should be considered comprehensively during the continuous-annealing process. The effect rule of microstructure and mechanical properties impacted by alloying elements, as well as the control of production process with microstructure and mechanical properties are reviewed in this paper. Simultaneously, we further present some suggestions for the development of the DP steel in the modern automobile industry.