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依据相变动力学理论,对高强度钢板热成形微观组织转变与力学性能预测模型进行研究。基于该模型建立汽车前立柱下角撑的热成形有限元模型,采用热-力-相变耦合分析方法对热成形过程进行仿真分析,得到制件的温度、组织和硬度的分布及变化。以高强度硼钢USIBOR1500为试验材料对汽车前立柱下角撑进行试制,并从成形件上取样进行微观组织分析和力学性能测试。结果表明,成形件的微观组织为均匀板条状马氏体,抗拉强度达到1 400MPa以上,3个典型位置的硬度均大于450HV,且力学性能分布与模拟结果一致,验证了所建立模型的可靠性。
According to the theory of phase change kinetics, the microstructure transformation and mechanical property prediction model of hot-formed high strength steel plate are studied. Based on the model, a finite element model of the thermoforming of the lower bracket of the front pillar was established. The thermoforming - phase transformation method was used to simulate the thermoforming process. The distribution and variation of temperature, microstructure and hardness were obtained. The high-strength boron steel USIBOR1500 as the test material on the car under the post before the trial, and from the molded parts for microstructure analysis and mechanical properties testing. The results show that the microstructure of the formed part is uniform lath martensite, the tensile strength reaches more than 1400MPa, the hardness of three typical locations is more than 450HV, and the mechanical properties are consistent with the simulation results. reliability.