成昆线在线钢轨焊接接头断裂分析

Investigation on rail fracture of Chengdu-Kunming railway

为研究在线钢轨焊接接头断裂原因,对取自成昆线的气压焊和闪光焊接头处的断裂钢轨试件进行了金相、硬度、宏观和微观断口分析。金相和硬度分析未发现明显异常组织和硬度分布。断口分析表明所研究的试件均为疲劳断裂,裂纹源位于焊瘤趾部或焊瘤内部靠近轨腰表面处。

To study the causes of fracture of welded rail joints,two fractured rail sa mples including a gas-pressure welding joint and a flash-butt joint were cut from Chengdu-Kunming railway for metallographical analysis,hardness test and macro and micro fracture analyses.No abnormity was found in the metallographi cal analysis and hardness test.The fracture analyses revealed that the fracture s are caused by fatigue,and the cracks initiated from the inclusions and voids at the toe of the fin for the gas-pressure welding joint sample or at the spot very close to the web surface in the fin.