Research On Hot Stamping Process Of Automotive Ultra-high-strength Boron Steel

The high-performance cars, electric cars, hybrid cars and other "green cars"get more and more attention. Energy saving, environmental protection,strengthening, lightweight are becoming the direction of future automotive.Strengthening and lightweight of automotive material are the most important. Inrecent years, productions of ultra-high-strength boron steel by hot stamping havebeen developing rapidly and achieve the requirement of lightweight.This paper used isothermal tensile thermal simulated test to study thethermal flow behavior of B1500HS and analyzed the influence of formingtemperature and strain rate on the flow stress-strain curve. The establishmentof the thermal flow mathematical model achieves mathematical description ofthe flow behavior of boron steel in high temperature. At the same time, thefinite element simulation software with the mathematical model can descriptthe performance of boron steel in simulation software. And then, the finiteelement simulation model of a typical hot stamping process formingpart—U-shaped part was established in ABAQUS software and the influence ofinitial temperature, the mold gap and stamping speed on the U-shaped partforming was analyzed. The results showed that the initial temperature and themold gap relatively large affect the forming process, especially on forming parttemperature distribution and thickness. And stamping speed slightly affects theforming time and has little effect on the results of the entire part forming.In order to obtain the law of automotive panels hot stamping formingcomprehensively, the simulation model of the B pillar strengthening part wasestablished in DYNAFORM software. First, the influence of process parameterson thickness, the forming limit diagram, the value of temperature drop andforming load was analyzed. And then, we got an optimal combination ofparameters by orthogonal test and gray system theory, which is a kind ofmulti-objective optimization. Finally, the correctness of the optimization methodand result were proved by simulation in DYNAFORM. This paper will providegreat theoretical and practical significance for the follow-up study on the hotstamping process.