高锰钢辙叉闪光焊接头缺陷分析

Analysis of defects in flash welded joint of hadfield steel frogs

文中利用金相显微镜、扫描电子显微镜及能谱分析、布氏硬度计等对多个高锰钢辙叉焊接接头着色渗透探伤后呈现的缺陷进行了分析。结果表明,中间焊接材料及中间焊接材料−钢轨钢熔合线附近产生的缺陷是由中间焊接材料中存在奥氏体‒铁素体相界裂纹或奥氏体沿晶裂纹引起的,化学成分波动、基体强度低以及焊接过程引入的残余应力是导致这些沿晶裂纹产生的主要原因,中间焊接材料−高锰钢熔合线附近产生的缺陷主要位于高锰钢一侧,高锰钢中的铸造微观缩松及磷共晶是这类缺陷形成的主要原因。为提高高锰钢辙叉焊接接头质量,在完善去除焊接残余应力的基础上,选用高强度单相奥氏体不锈钢,提高高锰钢铸造质量并严格控制杂质元素含量是主要途径。

In the present paper,optical microscope,scanning electron microscope,energy spectrum analysis and brinell hardness tester were used to analyze the defects of welded joint of hadfield steel frogs after dye penetrant inspection.Results showed that the defects on the intermediate welding material and near the fusion line between the welding material and rail steel were caused by the interface cracks between austenite and ferrite or austenite intergranular cracks in the welding material.The main reasons for these intergranular cracks were the fluctuation of chemical composition,the low strength of matrix and the residual stress introduced in the welding process.The defects near the fusion line between intermediate welding material and Hadfield steel mainly located in the side of hadfield steel,which were caused by casting micro shrinkage and phosphorus eutectic.In order to improve the quality of welded joints of Hadfield steel frog,removing the residual stress is one of the methods.More importantly,selecting high-strength single-phase austenitic stainless steel,improving the casting quality of hadfield steel and strictly controlling the content of impurity elements could be key solutions.