电极点蚀形貌对铝合金电阻点焊的影响

Effects of electrode pitting morphology on resistance spot welding of aluminum alloy

关键词:  电阻点焊  点蚀  电极失效  铝合金  有限元法

Key words:  resistance spot welding  pitting  electrode degradation  aluminum alloys  finite element method

摘要:

采用有限元分析和物理模拟相结合的方法,研究了环形和孔形两种电极点蚀形貌对铝合金AA5182电阻点焊的影响。结果表明,环形点蚀使两试件间接触半径增大,电流幅值基本不变而峰值略外移,所得熔核直径略有增大;孔形点蚀使试件间接触半径增大更为显著,电流密度降低,且由于此时界面中部没有电流流过,材料不能熔化,只能形成环形熔核。孔形点蚀使点焊接头强度大大降低,其对接头强度的不利影响远大于环形点蚀。

Abstract:

The effects of two types of electrode pitting morphologies, ring type and hole type on resistance spot welding of aluminum alloy 5182 were investigated by the combination of finite element analysis and physical modeling methods.Results showed that when using ring pitting electrode, the contact radius at faying surface is increased while the current distribution is not affected notably, and the nugget diameter is increased.When using hole pitting electrode, the contact radius at faying surface is increased further and the current density is decreased in the contact region.In addition, electric current does not flows through the central part of faying surface under such conditions, consequently, central part does not melt and only donut shape nugget is formed.Hole type pitting reduces the joint strength significantly, and its detrimental influence on joint quality is much greater than that of ring type pitting.