Cause of Transverse Fracture on U75V 60kg/m Heat-treated Rail
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摘要: 通过对中南通道伤损钢轨的宏观形貌、金相、显微硬度和化学成分检测分析, 确定钢轨断裂踏面被焊补了一层高锰钢金属层, 并造成近表层钢轨基体出现了马氏体、贝氏体脆性组织。在30 t轴重的载荷作用下, 钢轨表面产生了微细裂纹并扩展为横向裂纹, 最终造成钢轨断裂。Abstract: By detecting the macro morphology,microstructure,microhardness and chemical composition of broken rail from Central South Railway,a metal layer of high manganese steel were found being welded to the running surface of rail,which caused occurrence of brittle structure consisting of martensite and bainite formed in the base metal under weld layerdue to rapid cooling after welding.And rapid cooling resulted in thermal crack.The crack grew towards head,web and foot under the effect of 30 tons of axle load.In the end,the broken rail accident happened.
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Key words:
- heat-treated rail /
- transverse fracture /
- martensite
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