| WANG Chang-jian.Failure Analysis of High-speed Gear Shaft[J],45(6):192-197 |
| Failure Analysis of High-speed Gear Shaft |
| Received:January 18, 2016 Revised:June 20, 2016 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2016.06.029 |
| KeyWord:wind power generation speed-up gearbox high speed gear shaft effective hardening layer depth fatigue fracture surface carburizing heat treatment Martensite brittleness |
| Author | Institution |
| WANG Chang-jian |
Sichuan College of Architectural Technology, Deyang , China |
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| Abstract: |
| Objective Among the five pieces of 17Cr2Ni2Mo high-speed gear shaft of wind power generation speed-up gearbox, 4 pieces were found to have teeth broken phenomenon after assembling, leading to out of service of the high-speed gear shaft, and meanwhile resulted in stopping of installation and debugging. This work aimed to analyze the failure cause for the high-speed gear shaft, in order to identify the quality accident liability. Methods In this paper, comparative analysis was carried on the gear shaft to analyze the failure cause, including metallographic analysis, macrofractography, observation analysis of tooth surface, macroscopic examination, chemical analysis, effective hardening layer depth testing ,SEM, and so forth. Results The high speed gear shaft’s material was normal and its chemical composition was qualified. There were many fatigue shell ridges on the high speed gear shaft’s fracture, indicating that the gear fracture was fatigue fracture, and the fatigue source originated from the root. The metallurgical structure for the surface carburizing heat treatment layer of the gear shaft was normal, and the grain size was Grade 7, which was also qualified. The effective hardening layer depth of carburizing layer at the root of tooth, tooth surface, tooth top was all too deep, which did not meet the technical requirements of the product. The micro morphology of the fracture surface of the gear shaft was fatigue striation, and no obvious metallurgical defects were found. Conclusion The results showed that the failure type of the high-speed gear shaft was quick fatigue fracture, and its formation was caused by the excessive depth of carburizing layer at the root of tooth. |
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