| Abstract Scope |
A novel design of ultra-high strength press hardening automotive steel is proposed. Focusing on the contradiction between strength and toughness in steel materials, and considering the requirements of automotive lightweighting, low cost, and high efficiency, a vanadium microalloyed nanoscale precipitate press hardening steel, 34MnB5V, is designed. This design utilizes a significant amount of uniformly dispersed nanoscale vanadium carbide precipitates to refine the grain size while reducing the carbon content in austenite, suppressing the formation of brittle twin martensite. Based on existing automotive steel production conditions, without requiring any additional processes, a composite strengthening mechanism of ‘martensite matrix strengthening + nanoscale precipitate strengthening + grain refinement strengthening’ is employed to enhance the tensile strength to the level of 2000 MPa, while maintaining the ductility and bending properties comparable to the widely used 1500 MPa 22MnB5 press hardening steel. The precipitation process of vanadium carbides was also characterized in detail. |