The effect of electrode tip shape on resistance spot welding quality of AZ31 Mg alloy of 1 mm thickness was studied. The relationship between tensile shear force and microstructure of welding spot and the welding parameters with different electrode were compared, and the best welding parameters were obtained. The results show that electrode tip shape has obvious effect on tensile shear force and microstructure of welding spot. At the same time', the welding defects, fracture feature and formation causes were analyzed in order to improve the spot welding quality of magnesium alloy. It was found that the welding spot has higher strength and better microstructure by the double truncated cone electrodes compared to the spherical-flat electrodes, and welded joints with excellent properties can be obtained by truncated cone electrodes.%采用球面电极-平面电极和锥电极-锥电极焊接1 mm的AZ31镁合金,研究了不同电极形状焊接条件下,焊接电流、焊接时间对点焊接头的抗剪切力和焊点结晶形态的影响规律,分别确定了球面电极-平面电极和锥电极-锥电极焊接AZ31镁合金的最佳工艺规范.研究了电极形状对AZ31镁合金焊点中裂纹等缺陷的影响,对比分析了最佳工艺条件下,两种电极形状点焊接头的质量.结果表明,电极形状对镁合金焊点的抗剪切力及熔核结晶形态有显著影响,采用锥电极-锥电极可明显减少焊接缺陷的产生,获得更均匀的等轴晶熔核,有效地提高AZ31镁合金的焊点强度.
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