镁合金电阻点焊接头中的缺陷

Defects in joint for resistance spot welding of magnesium alloy

关键词:  镁合金  电阻点焊  焊接缺陷

Key words:  magnesium alloy  resistance spot welding  welding defects

摘要:

研究了新型轻质镁合金在电阻点焊中的主要缺陷,分析了焊接缺陷的形貌特点、形成原因和危害,为提高镁合金点焊接头质量提供了依据。结果表明,在镁合金电阻点焊接头中的裂纹为结晶裂纹,与电流特性、结晶时的应力状态和成分偏析有关;缩松和缩孔的产生主要与焊接过程中金属热膨胀及焊接后期锻压力大小有关;电极粘附和焊接喷溅是镁合金点焊中最常见的缺陷,产生的主要原因是电极与工件以及工件与工件界面处局部过热造成的。

Abstract:

The defects of new light material Mg alloy in resistance spot welding(RSW) were studied.Their appearance feature,formation causes and damages were analyzed,which offers the proof to improve the quality of joint in resistance spot welding of Mg alloy.The results shows that cracks in the joint of RSW of Mg alloy are solidification crack,which are dependent on the welding current character,stress condition and component segregation at solidification.Shrinkage porosity and shrinkage cavity have relation with heat expansion of metal in welding process and forge force in later welding time.Electrode stick and expulsion are the most common defects in RSW of Mg alloy,which are caused by the local overheat at the interface of electrode-workpiece and workpiece-workpiece.