Anisotropy Characterization And Forming Limit Diagram Construction Of High Strength Steel DP590 At Warm Deformation

High-strength steel has been widely used in automobile manufacturing of new energy vehicles due to its advantages of high strength and high ductility,which is conducive to reducing the weight and ensuring the driving safety.In this work,the mechanical properties of highstrength steel DP590 at room temperature and high temperature were studied.The main contents are as follows:(1)Based on Nakazima test and biaxial tensile test at room temperature,the necking and fracture forming limit diagram of high strength steel DP5 90 was constructed,and the effect of above test methods on the construction of the sheet forming limit was discussed.(2)Based on the uniaxial tensile test and simulation at room temperature,the JohnsonCook(JC)fracture model and GTN model of DP590 steel were constructed.At room temperature,the biaxial tensile test with a 4:4 tensile ratio was carried out on a cruciform specimen with a large notch.The yield criterion parameters of High strength steel DP590 about YLD2000-2D were obtained based on the test and reverse recognition method.The forming limit of DP590 steel at room temperature was investigated by finite element simulation and the constructed model.(3)The thermal uniaxial tensile tests at 300℃,400℃ and 500℃ were carried out.The hardening criterion of DP590 steel were constructed,and the effect of temperature on hardening parameters was analyzed.The YLD2000-2D anisotropic yield criterion of the DP590 steel at 300℃,400℃ and 500℃ was constructed by the equal-scale biaxial tensile test of the notched cruciform specimen.Furthermore,the effect of temperature on the yield criterion parameters was discussed.(4)The forming limit points of DP590 steel under the plane strain state at different temperatures were constructed by cruciform specimen with reduced thickness in central area.Forming limit prediction was carried out by the finite element simulation,and the forming limit curves at each temperature were predicted based on the identified YLD2000-2D anisotropic yield criterion.