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

Samples were taken from different positions of U-shaped parts of CR1500HF 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.