双相钢板料的单向拉伸断裂失效研究(Ⅰ)——数字图像相关技术试验

Fracture of dual phase steel sheets under uniaxial tension(I):experimental study with dic techniques

通过数字图像相关技术试验研究了双相钢平板单向拉伸试件的拉伸变形和断裂失效过程,与理论结果对比分析了集中性失稳带的分布和方向。试验研究结果表明,试件的变形过程包括均匀变形、分散性失稳、集中性失稳和拉断4个阶段;集中性失稳的区域呈"×"形分布,与加载方向约成57o;起裂点位于局部颈缩截面的中心点处;双相钢的延伸率为18%。

Dual phase(DP) steel is one of the most promising materials for the present automotive lightweight design.However,the widespread use of DP steel in the automotive industry is hampered by its relatively poor ductility.The deformation and failure process of the DP steel uniaxial tension specimen are studied by using the digital image correlation(DIC) technique,and then the distribution and inclined angle of the localized necking zone are also compared between experimental and theoretical results.It is found that the specimen's deformation is comprised of four different stages,namely uniform deformation,diffused necking,localized necking and tensile fracture.The localized necking distribution band has a 'x' shape and the inclined angle is about 57° with the longitudinal direction of the specimen.The crack initiates in the center of necking section.The present DP steel's elongation δ50mm is about 18%.