{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,18]],"date-time":"2026-07-18T03:50:34Z","timestamp":1784346634861,"version":"3.55.0"},"reference-count":34,"publisher":"MDPI AG","issue":"19","license":[{"start":{"date-parts":[[2025,9,26]],"date-time":"2025-09-26T00:00:00Z","timestamp":1758844800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"crossref","award":["52475459"],"award-info":[{"award-number":["52475459"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"crossref"}]},{"name":"Science and Technology Project of Fujian Province, China","award":["2025J01406"],"award-info":[{"award-number":["2025J01406"]}]},{"name":"Science and Technology Project of Fujian Province, China","award":["2022HZ024009"],"award-info":[{"award-number":["2022HZ024009"]}]},{"name":"Science and Technology Project of Fujian Province, China","award":["2021HZ024006"],"award-info":[{"award-number":["2021HZ024006"]}]},{"name":"Engineering Research Center of Anti-Fatigue Manufacturing for Marine Equipment, Fujian, China","award":["Z823291"],"award-info":[{"award-number":["Z823291"]}]},{"name":"Research Project on Manufacturing Technology for Long-Life Fatigue-Resistant Connecting Pins of Xiamen, Fujian, China","award":["2024350204006292"],"award-info":[{"award-number":["2024350204006292"]}]},{"name":"Major Science and Technology Project of Xiamen, Fujian, China","award":["3502Z20231011"],"award-info":[{"award-number":["3502Z20231011"]}]}],"content-domain":{"domain":["www.mdpi.com"],"crossmark-restriction":true},"short-container-title":["Materials"],"abstract":"<jats:p>The fracture behavior of a locking pin used in the penultimate-stage blades of a 600 MW steam turbine in a thermal power plant was investigated through microstructural and microhardness characterization, fracture surface and energy-dispersive spectroscopy (EDS) analysis, as well as finite element load simulation. The microhardness values measured on the cross-section of the service pins ranged from 528 to 541 HV0.1, showing little difference from the unused pins. Scanning electron microscopy analysis revealed that approximately 70% of the fracture surfaces exhibited an intergranular \u201crock candy\u201d morphology. The results indicate that pin failure was primarily caused by the combined effects of fretting wear and stress corrosion cracking (SCC). Specifically, vibration at the blade root, impeller, and pins due to start\u2013stop cycles and load variations led to fretting wear, forming pits approximately 75 \u03bcm in size. Under the combined effects of weakly corrosive wet steam environments and shear stresses, SCC initiated at the high stress concentration points of these pits. Early crack propagation primarily followed original austenite grain boundaries, while later stages mainly extended along martensite plate boundaries. As cracks advanced, the cross-sectional area gradually decreased, causing the effective shear stress to increase until it exceeded the shear strength, ultimately leading to fracture. These findings not only provide a scientific basis for enhancing the reliability of steam turbine locking pins and extending their service life, but also contribute to a broader understanding of the failure mechanisms of key components operating under corrosive and fluctuating load environments.<\/jats:p>","DOI":"10.3390\/ma18194487","type":"journal-article","created":{"date-parts":[[2025,9,26]],"date-time":"2025-09-26T12:33:03Z","timestamp":1758889983000},"page":"4487","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Inspection and Modeling Analysis of Locking Pins in the Penultimate-Stage Blades of a 600 MW Steam Turbine"],"prefix":"10.3390","volume":"18","author":[{"given":"Ke","family":"Tang","sequence":"first","affiliation":[{"name":"Sichuan Huadian Gongxian Power Generation Co., Ltd., Yibin 644500, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Weiwen","family":"Chen","sequence":"additional","affiliation":[{"name":"College of Marine Equipment and Mechanical Engineering, Jimei University, Xiamen 361000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jiang","family":"Zhu","sequence":"additional","affiliation":[{"name":"Sichuan Huadian Gongxian Power Generation Co., Ltd., Yibin 644500, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Binhao","family":"Yi","sequence":"additional","affiliation":[{"name":"Sichuan Huadian Gongxian Power Generation Co., Ltd., Yibin 644500, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Qing","family":"Hao","sequence":"additional","affiliation":[{"name":"Sichuan Huadian Gongxian Power Generation Co., Ltd., Yibin 644500, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jiashun","family":"Gao","sequence":"additional","affiliation":[{"name":"College of Marine Equipment and Mechanical Engineering, Jimei University, Xiamen 361000, China"},{"name":"School of Marine Mechatronics, Xiamen Ocean Vocational College, Xiamen 361000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zhilong","family":"Xu","sequence":"additional","affiliation":[{"name":"College of Marine Equipment and Mechanical Engineering, Jimei University, Xiamen 361000, China"},{"name":"Chengyi College, Jimei University, Xiamen 361000, China"},{"name":"Engineering Research Center of Anti-Fatigue Manufacturing for Marine Equipment, Xiamen 361000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bicheng","family":"Guo","sequence":"additional","affiliation":[{"name":"College of Marine Equipment and Mechanical Engineering, Jimei University, Xiamen 361000, China"},{"name":"Engineering Research Center of Anti-Fatigue Manufacturing for Marine Equipment, Xiamen 361000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shiqi","family":"Chen","sequence":"additional","affiliation":[{"name":"College of Marine Equipment and Mechanical Engineering, Jimei University, Xiamen 361000, China"},{"name":"Engineering Research Center of Anti-Fatigue Manufacturing for Marine Equipment, Xiamen 361000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,9,26]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"134425","DOI":"10.1016\/j.energy.2025.134425","article-title":"Thermodynamic performance analysis of steam power plants during deep peak shaving processes: Integrating a novel top turbine system in ultra-low loads","volume":"315","author":"Sun","year":"2025","journal-title":"Energy"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"134200","DOI":"10.1016\/j.energy.2024.134200","article-title":"Investigation on the allowable load ramping-up rate and wet-to-dry conversion time of a 660 MW supercritical coal-fired power plant with deep peak-shaving work conditions","volume":"314","author":"Liu","year":"2025","journal-title":"Energy"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"127415","DOI":"10.1016\/j.applthermaleng.2025.127415","article-title":"Flow characteristics and backpressure optimization of low-pressure stages in steam turbines under low flow rate conditions","volume":"278","author":"Han","year":"2025","journal-title":"Appl. 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