钢轨铝热焊接头裂纹产生原因分析

Analysis of the causes of crack in the thermit welded joint of rails

通过断口宏微观形貌观察、扫描电镜及能谱分析、金相显微组织分析等手段对伤损铝热焊接头裂纹的产生原因进行分析。结果表明:伤损铝热焊接头焊后去除冒口时,沿钢轨轨底宽度方向的去除冒口的力是焊接接头在轨底角焊筋表面夹渣、夹砂、疏松等焊接缺陷处产生裂纹的主要原因;裂纹源区组织异常,存在大量块状和网状铁素体,促进了裂纹在焊接缺陷处的开裂。

The failure cause of the thermit welded joint was analyzed by means of fracture macroscopic and microscopic morphology analysis, scanning electron microscopy observation and energy spectrum analysis, metallographic examination. The results show that the force of removing the riser, along the width of the bottom of the rail, is the main cause of the crack. The force cause crack along the welding surface defects such as slag inclusion, sand inclusion and porosity. The abnormal microstructure, a large number of massive and reticular ferrite, which promotes the cracking of the crack at the welding defects.