• CN: 11-2187/TH
  • ISSN: 0577-6686

Journal of Mechanical Engineering ›› 2025, Vol. 61 ›› Issue (11): 34-44.doi: 10.3901/JME.2025.11.034

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Experimental Study on the Influencing Factors of Bending Fatigue Strength of 18CrNiMo7-6 Gear

CHEN Difa, LIU Huaiju, ZHANG Xiuhua, LIN Qinjie, PAN Jiangsong   

  1. State Key Laboratory of Mechanical Transmission for Advanced Equipment, Chongqing University, Chongqing 400044
  • Received:2023-12-24 Revised:2024-05-13 Published:2025-07-12

Abstract: 18CrNiMo7-6, as the main material for the gear of high-end equipment such as offshore wind turbines, heavy mining equipment, large warships, and high-speed trains, its bending fatigue performance is an important bottleneck that limits equipment reliability, fatigue life, and power density. However, the specific impact of processes such as grinding and shot peening on the bending fatigue strength of gears is not yet clear, and the conversion between bending fatigue limits at different reliability levels has not been discussed, significantly restricting the lean design of high-performance gears. The bending fatigue tests of 18CrNiMo7-6 gears using a series of processes including carburizing and grinding, ion implantation, fine particle peening, barrel finishing, shot peening, tooth surface plus end face shot peening, and dual shot peening were systematically carried out. More than 700 effective bending fatigue test points were obtained, with a test duration of over 7 000 h. In addition, and a prediction formula for the bending fatigue performance of gears of this material grade was proposed. The results show that within the studied range of processes, the bending fatigue limit range of 18CrNiMo7-6 gears is 482-762 MPa; the conversion coefficient range of bending fatigue limits for 50% reliability and 99% reliability ranges from 0.841 to 0.965, with the recommended value of 0.929. The bending fatigue limit value of gears is mainly related to processing technology, module, specific processing environment of the enterprise, etc. The average absolute prediction error of the bending fatigue limit prediction formula for gears considering the surface integrity parameters is 6.19%, providing valuable research methods and data support for the development of high power-density gear transmission in engineering practice.

Key words: 18CrNiMo7-6 gear, bending fatigue, strengthening process, conversion coefficient

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