采用有限元方法对板料直流电阻对焊过程中的接口张开、接头表面纵向裂纹问题进行了研究 .分析表明 ,焊接过程中金属的塑性流动导致界面质点力学状态发生动态变化 ,包括应力大小和拉压应力状态的变化 .变形过程中 ,界面质点在x轴方向所受的拉应力是接头内部产生层状撕裂的力学原因 ,在 y轴方向和z轴方向所受拉应力是产生接口张开和形成飞边纵向裂纹的力学原因 . The finite element method was used to study the interface flaws and the longitudinal cracks on the joint surface during the DC resistance butt welding process.The analysis shows that the plastic flow of the metal causes the dynamic changes of the mechanical properties of the interface particle during the welding process, During the deformation process, the tensile stress of the interface particles in the x-axis direction is the mechanical reason for the layered tearing in the joint, and the tensile stress in the y-axis direction and the z-axis direction is caused by the interface tension Mechanical Cause of Opening and Forming Crack in Longitudinal Crack.