锆材钨极氩弧焊焊接件腐蚀机理

采用X射线衍射、电化学测试,扫描电镜观察和能谱分析,系统研究了钨极氩弧焊接锆材焊缝区域的组织结构及耐腐蚀性能,探究其腐蚀机理。结果表明:锆材焊接件腐蚀方式为焊缝晶间腐蚀。产生晶间腐蚀的原因为:氩气保护不充分及焊丝含有少量的氧,在焊缝区域晶界形成了锆的氧化物,导致晶界与晶粒内部存在电化学不均匀性,致使晶界的溶解电流密度大于晶粒,发生晶间腐蚀。

Corrosion Mechanism of Zirconium Butt Joint by Tungsten Inert Gas Welding

In order to solve the corrosion issues that occur in the weld zone (WZ) of zirconium material applied in the industrial community, X-ray diffraction (XRD), electrochemical analysis, scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) were used to investigate the microstructure and corrosion resistance of the zirconium butt joint by tungsten inert gas (TIG) welding. Also, the mechanism of corrosion was discussed. It is found that the corrosion pattern of zirconium butt joint is intergranular corrosion. The factors that cause intergranular corrosion are the inadequate protection of argon and a trace amount of oxygen existing in the soldering wires, which facilitates the generation of zirconium composite oxides that result in the electrochemical inhomogeneity between crystal boundaries and particles. Consequently, the dissolve current density of crystal boundaries is larger than that of the grains, which leads to intergranular corrosion