汽轮机高温螺栓断裂原因

Fracture Causes of High Temperature Bolt of Steam Turbine

某汽轮机的高温螺栓在机组运行过程中发生了断裂,采用宏观观察、化学成分分析、力学性能试验、宏观组织检验、金相检验、断口分析等方法,对高温螺栓的断裂原因进行了分析。结果表明:该汽轮机的高温螺栓晶粒较粗大,且长期在高温高压环境下服役,造成碳化物逐步析出、材料冲击韧性下降。在机组启、停机及机组负荷波动带来的冲击应力下,该高温螺栓最终发生了脆性断裂。

The high temperature bolt of a steam turbine fractured during the operation of the unit. The fracture causes of the high temperature bolt were analyzed by means of macro observation, chemical composition analysis, mechanical property test, macro structure inspection, metallographic examination and fracture analysis. The results show that the grain size of the high temperature bolt of the steam turbine was coarse, and it had been in service under high temperature and high pressure for a long time, resulted in the gradual precipitation of carbide and the decrease of impact toughness of the material. Under the impact stress caused by unit start-up, shut-down and unit load fluctuation, the high temperature bolt finally had brittle fracture.