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某火力发电厂主汽门螺栓发生断裂失效,通过宏观断口分析、化学成分分析、金相组织分析以及力学性能检验等手段对高温主汽门螺栓的断裂事故进行了综合分析。结果表明:断口形貌为典型的脆性断口,螺栓的微观组织粗大,断口的硬度偏低,各项力学性能趋于标准的下限值,老化现象明显,不能满足正常工况下的服役强度和韧塑性要求,最后引起断裂事故。
The rupture failure of the main steam valve bolt of a thermal power plant was carried out. The fracture of high temperature main steam valve bolt was analyzed comprehensively by macroscopic fracture analysis, chemical composition analysis, microstructure analysis and mechanical property test. The results show that the fracture morphology is a typical brittle fracture, the microstructure of the bolt is coarse, the fracture hardness is low, and the mechanical properties tend to the standard lower limit value, the aging phenomenon is obvious, which can not meet the service strength under normal conditions and Tough plastic requirements, the final cause fracture.