电机配水环管焊缝裂纹原因分析

Electric Machinery Water Distribution Ring Pipe Crack Analysis

某设备制造厂电机配水环管立缝在消除应力热处理后,熔合线附近出现裂纹。钻孔截取裂纹局部,肉眼可见裂纹表面呈暗褐色。通过扫描电镜、能谱仪及光学显微镜对裂纹产生原因进行了深入分析,认为该裂纹属高温形成的再热裂纹,可以通过改变预热、后热温度,提高焊接质量以降低应力集中等方法来防治。

A crack is found after SR heat treatment in the vertical welding fusion line for water distribution ring pipe of a electric machinery.Part of the crack is cut by drill,the crack surface is dust-colour under naked eyes.Microcosmic appearance is intergranular(IG) fracture under SEM.Energy chart shows that more Mn and O is enrichment at craze grain boundary.Optical microscope photos shows the crack come of fusion line,then it enlarges along overheat area near fusion line.So the crack is reheat crack,it can be prevented and cured by changing warm-up and post heat temperature,improving weld quality to reduce stress concentration.