动态感应加热消除轨面堆焊热影响区马氏体组织

Using dynamic induction heating to inhibit martensite structure formed in heat-affected zone of U71Mn steel rail aftersurface welding

关键词:  动态感应加热  U71Mn钢轨  堆焊  马氏体组织

Key words:  dynamic induction heating  U71Mn steel rail  surface welding  martensite

摘要:

采用动态感应加热的方法消除了U71Mn钢轨轨面堆焊后热影响区的马氏体组织.通过光学显微组织分析和显微硬度测试对马氏体组织的消除效果进行了识别.结果表明,U71Mn钢轨在冷焊的工艺下,热影响区内会产生裂纹,显微组织为马氏体组织.随着预热和后热温度的提高,马氏体组织的消除效果越加明显.当预热温度为320℃,后热温度为550℃时可以完全避免热影响区内马氏体组织的形成,生成比母材珠光体晶粒细小的索氏体组织,热影响区的硬度分布均匀.

Abstract:

A dynamic induction heating method was used to inhibit the formation of martensite in heat-affected zone(HAZ) of U71 Mn steel rail after surface welding. The inhibition of martensite structure was characterized by optical microstructure analysis and microhardness testing. The experimental results showed that when the U71 Mn steel rail was welded in cold welding condition, cracks would form directly in the heat-affected zone, and the microstructure was martensite. With the increase of preheating and post-heating temperature, the amount of martensite reduced significantly. When the preheating temperature was 320℃ and post-heating temperature was 550℃, the martensite structure could be inhibited completely, and the heat-affected zone consisted of sorbite structure whose size was smaller than pearlite structure in the base metal. The microhardness of the heat-affected zone also distributed uniformly.