起重机用钢轨断裂原因分析

Cause Analysis on Fracturing of Crane Rail

采用金相检验、化学成分分析、力学性能测试及断口分析等方法对某起重机用钢轨的断裂原因进行了分析。结果表明:钢轨断裂为一次性脆性断裂,断裂起源于轨底的刮擦凹坑处;另刮擦凹坑处存在严重的脱碳现象,极大降低了该处材料的力学性能,加之钢轨材料的硅含量严重超标也增加了材料的脆性,从而导致在起重机行车运行过程中,钢轨轨底刮擦凹坑处产生应力集中,萌生裂纹并迅速扩展,造成钢轨脆性断裂;脱碳现象的存在说明刮擦凹坑处受热较严重,分析认为是电弧擦伤所致。

By means of metallographic analysis,chemical compositions analysis,mechanical properties test and fracture analysis,the fracture reason of crane rail was analyzed.The results indicate that fracture of the rail was one-time brittle fracture and the fracture started from the scratch pits at the rail bottom.And there had serious decarburization phenomenon at the scratch pits area,which greatly reduced mechanical properties of the material.At the same time,Si content was higher than the required value,which also increased the brittleness of the material.So during the operation process of the crane rail,stress concentration formed at the scratch pits and cracks initiated and expanded quickly,and finally resulted in the fracture of the rail.The existence of decarburization phenomenon showed that the scratch pits area had been heated seriously,so it was thought that the scratch pits were caused by the electric are abrasion.