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基于Johnson-Mehl-Avrami相变动力学模型和Koistinen-Marburger方程,建立了硼钢22Mn B5车门防撞梁热冲压过程的热机械-相变耦合有限元模型,得到了车门防撞梁热冲压过程中板料温度、微观组织及维氏硬度的分布特征,研究了保压压力和保压时间对防撞梁热冲压零件的性能影响.仿真结果表明:车门防撞梁顶部冷却速度为137.3℃·s-1,侧壁冷却速度为69.8℃·s-1,冷却速度决定了防撞梁各个部位的微观组织和维氏硬度;随着保压压力的增大,获得95%以上马氏体的防撞梁的保压时间缩短,可加快生产节拍.进行了防撞梁热冲压试验,对微观组织及维氏显微硬度进行了检测.结果表明:车门防撞梁保压10 s后,顶部及侧壁均已转化为板条状马氏体组织,且顶部硬度为508 HV,侧壁硬度为474 HV.
Based on the Johnson-Mehl-Avrami phase transition kinetic model and the Koistinen-Marburger equation, a thermo-mechanical-phase-change coupled finite element model of the hot stamping process of the 22Mn B5 door beam was established. During the hot stamping process, The effects of dwell pressure and dwell time on the performance of the hot stamping beam hot stamping parts were studied.The simulation results show that the cooling speed of the top of the bumper beam is 137.3 ℃ · s -1, the cooling rate of the side wall is 69.8 ℃ · s-1, the cooling rate determines the microstructure and Vickers hardness of various parts of the impact beam; with the holding pressure increases, get more than 95% martensite The holding time of the impact beam is shortened, which can speed up the production cycle.Through the hot stamping test of the impact beam, the microstructure and the microhardness of Vickers were tested.The results show that after the pressure bump on the door impact beam for 10 s, The sidewalls have all been transformed into lath martensite with a top hardness of 508 HV and a sidewall hardness of 474 HV.