CR1500HF热成形钢U形件不同位置的高速拉伸性能及其有限元模拟

High-Speed Tensile Properties and Their Finite Element Simulation at Different Positions of CR1500HF Hot-Forming Steel U-shaped Parts

在CR1500HF热成形钢U形件不同位置取样,进行应变速率在1~500 s-1的拉伸试验,研究了不同位置拉伸性能的差异和应变速率对热压成形件拉伸性能的影响;建立材料拉伸有限元模型,模拟分析了该钢的高速拉伸性能和拉伸试样加持端应力分布。结果表明:该热压成形U形件侧壁位置的抗拉强度和屈服强度低于法兰和底部位置,在进行碰撞分析时需考虑部分位置因冷却不足强度降低的影响;随着应变速率的增加,U形件不同位置的屈服强度和抗拉强度均增大;由拉伸有限元模型模拟得到的真应力-真塑性应变曲线与combined S-H本构模型拟合得到的曲线吻合较好,应变速率1, 500 s^(-1)下真应力均方根误差分别为19.98,39.48 MPa;高速拉伸过程中拉伸试样夹持端大部分处于弹性变形阶段,应变片粘贴位置距试样圆弧处的距离应大于19 mm。

Samples were taken from different positions of U-shaped parts of CR1500 HF hot-forming steel, and tensile tests with strain rates from 1 to 500 s^(-1) were carried out. The difference in tensile properties at different positions and the effect of strain rate on the tensile properties of the hot-stamped parts were studied.The material tensile finite element model was established to analyze the high-speed tensile performance of the steel and the stress distribution at the clamping end of the tensile specimen. The results show that the tensile strength and yield strength on side-wall of the hot-stamped U-shaped part were lower than those at flange and bottom positions;therefore, in the collision analysis, it was necessary to consider the influence of the strength reduction at some positions due to insufficient cooling. With increasing strain rate, the yield strength and tensile strength at different positions of the U-shaped part increased. The true stress-true plastic strain curves simulated with the tensile finite element model were in good agreement with those obtained by combined S-H constitutive model;the root-mean-square errors of the true stress at strain rate of 1, 500 s^(-1) were 19.98,39.48 MPa, respectively. During high-speed tensile, most of the clamping end of tensile specimens were in elastic deformation stages, and the distance between the attachment position of the strain gauge and the arc of the specimen should be greater than 19 mm.