20Cr1Mo1VTiB钢制高温紧固螺栓断裂失效分析

Failure Analysis on Fracture of High Temperature Fastening Bolts of 20Cr1Mo1VTiB Steel

某火力发电厂汽轮机用20Cr1Mo1VTiB钢制高温紧固螺栓在安装时发生断裂。通过宏观检验、化学成分分析、金相检验、断口分析、力学性能测试等方法对螺栓断裂的原因进行了分析。结果表明:高温紧固螺栓材料的冶炼工艺中由于化学元素含量控制不当,导致碳含量严重超标,造成螺栓的冲击吸收能量及塑性下降,最终促使螺栓发生断裂。

The high temperature fastening bolts of 20 Cr1 Mo1 VTiB steel for steam turbine of a thermal power plant broke during installation.The fracture causes of bolts were analyzed by means of macro examination,chemical composition analysis,metallographic examination,fracture analysis and mechanical property test.The results show that in the smelting process of materials of the high temperature fastening bolts,the carbon content was seriously exceeded due to the improper control of the chemical elements content,resulting in the decrease of impact absorption energy and plasticity of the bolts,which eventually led to bolt fracture.