预成形−高速冲击点焊工艺连接界面分析

Analysis of joining interface of preform−high rate impact spot welding

本文采用预成形−高速冲击点焊工艺,获得到了连接强度较好的DP590/Al3003异种材料点焊接头。通过光滑粒子动力学模拟方法(SPH)分析了接头连接界面形成规律,并实验研究了接头界面特征与形成机理。结果表明:接头界面具有波形特征,连接强度与波形界面的波形参数存在一定关系;预成形直径较小或放电能量较低时外侧区域界面波形不明显;随预成形直径增加,外侧区域出现界面波且波长波幅呈增加趋势;一定范围内,随放电能量增加,即飞板速度增加时,连接界面中间区域的界面波的波长逐渐减小而波幅增加,外侧区域界面波波长和波幅均增大,连接强度增加;SEM和EDS分析结果表明,连接界面产生了裂纹和旋涡组织,并生成了少量金属间化合物。

The preform−high rate impact spot welding process was proposed to join the aluminum and steel in this paper,and DP590/Al3003 joints with satisfied joining strength were obtained.The joint interface formation rule was investigated with smooth particle hydrodynamics(SPH)analytical method,and the interface characters and formation mechanism were experimental analyzed.The results show that,the joint interface shows the wave characters and the joint tensile resistance is related to the interface wave parameters.Few wave shows in the outside zone of interface when the preform diameter or discharging energy is small.With the preform area enlarges,the wavelength and amplitude increase in the outside zone.With the increase of discharging energy in a range,meanwhile with the increase of impact rate of flyer sheet,the wavelength decreases and amplitude increases in the middle zone of interface,but both increase in outside zone,and the tensile resistance enhances.The SEM and EDS results show that micro-crack and vortex microstructures appear inside the interface and interlayer metal compounds generate.