某客运专线道岔胶接绝缘钢轨用高强度螺栓在安装使用1 a(年)后出现少量断裂失效。采用宏观分析、化学成分分析、力学性能测试、金相检验以及扫描电镜断口分析等方法, 对螺栓的断裂原因进行了分析。结果表明: 该高强度螺栓断裂主要是由第一类回火脆性引起的, 而淬火时形成的少量上贝氏体加速了螺栓的断裂。最后提出了改进措施。

A small amount of high strength bolts used for glued insulated rail on turnout of passenger line fractured after service for about one year. By means of macro analysis, chemical compositions analysis, mechanical properties testing, metallographic examination, SEM fracture observation and so on, the fracture reason of the bolts was analyzed. The results show that the main reason for fracture of the high strength bolts was attributed to the one-step temper brittleness, and a little amount of upper bainite which formed during quenching accelerated the fracture. Finally improvement measures were put forward.