重载铁路钢轨铝热焊接头S形断裂失效原因分析  

Failure Cause Analysis of S-shaped Fracture of Thermit Welded Joint in Heavy Haul Railway

作　　者：胡杰[1] HU Jie(Metals ＆ Chemistry Research Institute ,China Academy of Railway Sciences ,Beijing 100081 ,China)

机构地区：[1]中国铁道科学研究院金属及化学研究所,北京100081

出　　处：《铁道建筑》2017年第3期125-128,共4页Railway Engineering

摘　　要：采用扫描电子显微镜、光学显微镜、直读光谱仪、布氏硬度计对重载铁路钢轨铝热焊接头S形断裂件的断口微观形貌、金相组织、化学成分、硬度进行了检验分析。结果表明:铝热焊接头伤损属于起源于轨腰焊筋表面缺陷处的纵向裂纹引起的钢轨S形断裂;轨腰焊筋尖端表面存在大尺寸疏松缺陷是轨腰纵向裂纹产生的主要原因;同时焊缝内部存在缩孔和大量疏松缺陷,降低了焊缝强度,促进了裂纹的快速扩展,最终导致脆性断裂。The micrograph of fracture surface, microstructure, chemical composition and hardness of S-shaped fractured parts of thermit welded joint in heavy haul railway were analyzed by scanning electron microscopy, optical microscopy, direct reading spectrometer and Brinell hardness tester. The results show that the damage of the thermit welded joint belongs to the S-shaped rail fracture cause by longitudinal crack, which originats from the surface defect of rail waist welding. The large-scale porosity defect on the tip of waist welding is the main reason for the longitudinal crack in the waist. At the same time, there are shrinkage cavity and a large number of porosity defects within the weld, reducing the weld strength and promoting the rapid expansion of the crack, eventually leading to britde fracture.

关 键 词：重载铁路 铝热焊接头断裂 检验分析 S形断裂 纵向裂纹 疏松 脆性断裂 

分 类 号：U213.92[交通运输工程—道路与铁道工程]