重载线路铝热焊接头轨头下部夹杂缺陷分析

Analysis of rail head underpart inclusion defects of heavy haul railway thermit welding joints

我国重载运煤专线运量不断增加,钢轨铝热焊接头的伤损问题日益突出。本文着重对75 kg/m钢轨铝热焊接头的夹杂缺陷样本进行研究,采用扫描电镜观察断面缺陷特征,并对缺陷上典型特征的夹杂杂质进行能谱分析,同时对比分析了缺陷区域和一般焊缝区域的金相组织,认为此类缺陷产生与焊接过程预热及浇注温度偏低、轨缝过大等焊接过程工艺控制不足有关,提出加强焊前设备管理,严格焊接过程工艺控制可减少或避免此类缺陷的产生。

Besides the mounting coal volume of heavy haul railways in our country,the defect problems of thermit welding joints were becoming more and more serious.Aiming to the study of inclusion defects of 75 kg/m rail thermit welding joints,a defect sample had been knocked apart to have a clear scanning by SEM on its feature section,while EDS analysis of the typical impurities on the surface had also been carried.At the same time,the metallurgical structure of the defect area and the general weld region were compared.It could be concluded that such defects were related to lower temperature of preheating,lower pouring temperature,wider welding seam and so on.Therefore,it was proposed that strengthening the welding equipment management and welding process control could greatly reduce the generation of such defects.