中文摘要：

通过翻边实验和槽型件实验,研究了先进高强度双相（DP）钢在小半径拉弯成形中的断裂特性.翻边实验表明,高强度DP钢强度级别越高越容易发生剪切断裂.槽型件实验与仿真表明,高强度DP钢的断裂特性与压边力大小关系密切,压边力大则弯曲圆角处容易发生剪切断裂;压边力小则易在侧壁上发生颈缩断裂.先进高强度DP钢最终的断裂模式是剪切断裂和颈缩断裂相互竞争的结果,任一断裂条件先达到则板料发生该种断裂.

英文摘要：

Fracture characteristics of advanced high strength DP（dual-phase） sheets in stretch-bending over a tight die radius were investigated through flanging and groove-shape dies.Flanging result shows the higher the strength grade of DP sheet is,the more chance shear fracture occurs.The groove-shape tests and simulations suggest the shear fracture around the tight radius only occurs under high BHF,and necking on the wall happens when BHF is low.The eventual failure mode during sheet metal forming operations of AHSS is viewed as the competition between necking and shear fracture,whichever criterion is satisfied first.