通过Deform有限元分析软件对3.8 mm厚22MnB5钢制轿车后桥横梁的热冲压成形过程进行了模拟, 分析了合模保压过程中板料的温度变化; 对22MnB5钢制后桥横梁进行了热冲压成形试验, 测试了热冲压过程中板料的温度变化, 并与有限元模拟结果进行了对比分析,研究了成形后横梁的显微组织和硬度。结果表明: 在热冲压成形过程中, 合模保压后板料温度快速下降, 冷却速率达到30 ℃·s-1以上, 可实现22MnB5钢的淬火强化; 试验测得热冲压成形过程中板料的温度变化曲线与模拟曲线一致, 相对误差在10%以内,模拟结果较准确; 热冲压成形件的最终显微组织为板条马氏体, 显微硬度达到480 HV以上。

The hot stamping process of the car rear axle beam made of 22MnB5 steel with the thickness of 3.8 mm was simulated by the finite element analysis software Deform. The temperature changes of the blank during the pressure-holding process after die clamping were analyzed. The hot stamping experiments were conducted on the 22MnB5 steel beam of the rear axle. The temperatures of the blank were measured during the hot stamping process and compared and analyzed with the finite element simulation results. The microstructure and hardness of the beam after hot stamping were also studied. The results show that during the hot stamping process, the temperatures decreased rapidly after die clamping and the cooling rate reached above 30 ℃·s-1, assuring the quenching strengthening of the 22MnB5 steel. The experimental temperature changing curve of the blank during hot stamping was in accordance with the simulated curve and the relative error was below 10%, indicating the accuracy of the simulation results. The microstructure of the hot stamped part consisted of lath martensite and the microhardness reached above 480 HV.