Hot Stamping of Boron Steel Using Partition Heating for Tailored Properties: Experimental Trials and Numerical Analysis

Hot-stamped components with tailored properties are becoming popular for their better performance in collision. In this article, an M-shaped part with varying properties was formed by hot stamping using partition heating. Different soaking temperatures induce different austenite fractions at the different regions of the blank, resulting in the partitioned microstructure and mechanical properties in a single part. In the high-temperature region, the average tensile strength and elongation are 1565 MPa and 8.65 pct, respectively, and the average tensile strength and elongation are 626 MPa and 24.37 pct, respectively, in the low-temperature region. A finite element model of hot stamping using partition heating was established based on the relationship of austenite fraction with heating temperature determined by the dilatometer test and the stress–strain curve of 22MnB5 with different austenite fractions acquired from the hot tensile test.The differences of temperature, thickness, and Vickers hardness in different zones of the M-shaped part during forming and quenching stages were analyzed. The effects of hot stamping parameters, such as stamping velocity and heating temperature, on the forming and mechanical properties of the tailored M-shaped part were investigated, providing theoretical guidance for the production of tailored hot-stamped components using partition heating.