镀锌钢板电阻点焊电极的失效分析

Analysis on Electrode Failure During Resistance Spot Welding of Zinc Coated Steel

采用光学显微镜、X射线衍射等方法研究了铬锆铜电极在点焊镀锌钢板时的失效形式,对电极内部组织及其硬度、导电性能在焊接过程中的动态变化进行了监测、分析。结果表明:铬锆铜电极的失效形式主要是塑性变形、合金化和坑蚀;随点焊进行,电极内部发生再结晶和析出相长大,导致电极头部显微硬度明显降低,但对导电性能影响不大;铬锆铜电极失效后端面合金化产物为Cu5Zn8相。

The alloying compound on the surface of CuCrZr electrode tip was examined by X-ray during spot welding of zinc coated steels and the microstructure and appearance of electrode tip were studied. The microhardness and electrical conductivity of CuCrZr electrode tip were tested. The results show that the failure of CuCrZr electrode is caused by deformation and pitting at the electrode tip, together with alloying on the surface of electrode tip. The microhardness at the tip of CuCrZr electrode decreases obviously due to recrystallization and coarsening of precipitates that have little influence on the electrical conductivity of electrode. CusZn8 are formed on the surface of failed CuCrZr electrode tip.