Heat Treatment of Metals ›› 2023, Vol. 48 ›› Issue (2): 212-218.DOI: 10.13251/j.issn.0254-6051.2023.02.033

• PROCESS RESEARCH • Previous Articles     Next Articles

Induction hardening process optimization of microalloyed medium carbon steel 48MnV for crankshaft connecting rod journal

Mao Xiaofeng1, Li Yajun2, Deng Shigui1, Li Xinkai2, Zhao Huan2, Wang Rong2   

  1. 1. Guilin Fuda Co., Ltd., Guilin Guangxi 541199, China;
    2. School of Mechanical and Electrical Engineering, Guilin University of Electronic Technology, Guilin Guangxi 541004, China
  • Received:2022-09-28 Revised:2023-01-02 Online:2023-02-25 Published:2023-03-22

Abstract: Optimum process of induction heat treatment of microalloyed medium carbon steel 48MnV crankshaft connecting rod journal was studied by means of contrast test with quenching energy, tempering conditions, heating time and cooling time as variables. The results show that the optimized induction heat treatment process consists of quenching power of 165 kW, current frequency of 9 kHz, heating time of 17 s, cooling interval time of 1 s, cooling time of 20 s, and tempering at 210 ℃ for 2.5 h. Under the optimized induction heat treatment process, the microstructure of the hardened layer of connecting rod journal is fine and uniform acicular martensite; the maximum hardness of the journal surface and the position 0.25 mm from the surface of fillet on both sides can reach 720.9, 690.0 and 667.1 HV, respectively, and the wear resistance is significantly improved; the residual stress on the surface of connecting rod journal and fillet is compressive stress, the residual stress of the transition fillet near the spindle end is up to -884.0 MPa, and the residual stress of the transition fillet near the flange end is -831.9 MPa. The fatigue limit load of the specimen is the highest, up to 3750 N·m. The greater the residual compressive stress after induction heat treatment, the better the bending fatigue strength of the crankshaft connecting rod journal.

Key words: 48MnV microalloyed medium carbon steel, crankshaft connecting rod journal, induction hardening, microstructure, fatigue strength

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