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对实验室炼制的780MPa级热镀锌双相钢进行成形性能研究,通过烘烤硬化实验和V形弯曲实验,研究了不同工艺参数对钢板抗凹陷性能和回弹性能的影响。通过扩孔实验深入分析了钢板塑性断裂过程中裂纹的形成与扩展机理。结果表明:小于2%的预应变量可以提高DP780钢的BH值;弯曲变形后实验钢板的回弹角随凸模圆角半径的增大而增大;DP780钢板发生塑性断裂过程中,裂纹通过孔洞相互贯通而形核,并沿着马氏体岛边缘呈“扭折”状进行扩展。
The forming performance of 780MPa hot-dip galvanized duplex steel was investigated. The effects of different process parameters on the anti-sagging performance and rebound resilience of steel plate were studied by bake hardening test and V-bending test. Through the hole expanding experiment, the formation and propagation mechanism of cracks in the plastic fracture of steel plate are analyzed in depth. The results show that the pre-strain of less than 2% can increase the BH value of DP780 steel. The rebound angle of the experimental steel increases with the increase of the fillet radius of the punch after bending deformation. During the plastic fracture of DP780 steel plate, The holes interpenetrate and nucleate, extending along the edge of the martensite island in a “kinked” shape.