Heat Treatment of Metals ›› 2023, Vol. 48 ›› Issue (7): 287-291.DOI: 10.13251/j.issn.0254-6051.2023.07.048

• TEST AND ANALYSIS • Previous Articles     Next Articles

Cracking failure analysis on high-speed intermediate shaft gear

Chen Shengchao1,2, Chen Yesheng3, Rong Zeyu1, Wang Hongwei1, Xu Hongxiang1, Zhao Shaofu1, Guo Jingqiang1   

  1. 1. Zhengzhou Research Institute of Mechanical Engineering, Zhengzhou Henan 450001, China;
    2. Zhengzhou University, Zhengzhou Henan 450001, China;
    3. Beijing Petroleum Machinery Co., Ltd., Beijing 102200, China
  • Received:2022-11-07 Revised:2023-04-21 Online:2023-07-25 Published:2023-09-04

Abstract: A 18CrNiMo7-6 steel high speed intermediate shaft gear of gearbox had abnormal vibration sound during the dynamic balance test after carburizing and quenching. After disassembly, it was found that the intermediate shaft gear had obvious axial crack at the axial diameter. After macro observation and multiple cutting, it was found that the crack source was located at the axle center of the large gear. The crack location of the main shaft was studied by chemical composition analysis and microstructure analysis. The results show that due to the incomplete dehydrogenation treatment of the large billet forgings, the hydrogen atoms gather to form hydrogen molecules over time, which causes the stress concentration inside the workpiece, leading to the delayed hydrogen embrittlement cracking of the gear shaft after carburizing and quenching, and resulting in the failure of the shaft gear.

Key words: high speed shaft gear, 18CrNiMo7-6 steel, cracking, hydrogen embrittlement, failure analysis

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