Cause analysis of bolt fracture of high pressure main steam valve of steam turbine in power station

Liming Xie; Jun Liu

doi:10.1117/12.2641073

24 October 2022 Cause analysis of bolt fracture of high pressure main steam valve of steam turbine in power station

Liming Xie, Jun Liu

Proceedings Volume 12289, International Conference on Intelligent Manufacturing and Industrial Automation (CIMIA 2022); 122890F (2022) https://doi.org/10.1117/12.2641073
Event: International Conference on Intelligent Manufacturing and Industrial Automation (CIMIA 2022), 2022, Kunming, China

Abstract

The high-temperature fastening bolt of the high-pressure main steam valve of the steam turbine of 330MW unit in a thermal power plant breaks during operation. In this paper, the causes of bolt fracture are analyzed by means of macro morphology observation, fracture SEM detection, microstructure detection, mechanical property detection and chemical composition detection. The results show that during the long-term high-temperature service, the matrix structure of the fastening bolt of the high-pressure main throttle valve is aging and carbide particles are gradually precipitated. With the increase of operation time, the carbide particles continue to aggregate and grow up and distribute along the grain boundary, and a large number of creep holes and creep cracks are formed on the grain boundary. A large number of coarse carbides and creep cracks lead to the decline of mechanical properties of bolts, especially the deterioration of impact toughness and tensile strength; The accumulation of creep cracks becomes the crack source. Under the impact load formed during the action of high-pressure main throttle valve, the stress concentration part of the bottom of the first thread of the bolt external thread cracks, and the cracks continue to expand, resulting in the brittle fracture of the bolt.

Citation Download Citation

Liming Xie and Jun Liu "Cause analysis of bolt fracture of high pressure main steam valve of steam turbine in power station", Proc. SPIE 12289, International Conference on Intelligent Manufacturing and Industrial Automation (CIMIA 2022), 122890F (24 October 2022); https://doi.org/10.1117/12.2641073

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