Heat Treatment of Metals ›› 2023, Vol. 48 ›› Issue (11): 185-190.DOI: 10.13251/j.issn.0254-6051.2023.11.029

• PROCESS RESEARCH • Previous Articles     Next Articles

Effect of composite heating process of induction furnace and pit furnace on quenched and tempered microstructure and mechanical properties of 40Cr steel

Wang Weimin1, Liu Anqi1, Guo Chuncheng1, Da Zhongzhong1, Qi Haiquan1, Han Xiangnan1, Xue Qihe2, Wei Minjun3   

  1. 1. School of Materials Science and Engineering, Guilin University of Technology, Guilin Guangxi 541004, China;
    2. HBIS Co., Ltd, Chengde Branch, Chengde Hebei 067000, China;
    3. Valin Arcelor Mittal Automotive Steel Co., Ltd., Loudi Hunan 417009, China
  • Received:2023-05-27 Revised:2023-09-07 Online:2023-11-25 Published:2023-12-27

Abstract: Composite heating process composed of induction furnace heating to 870 ℃ or 900 ℃ and then pit furnace isothermal heating at 860 ℃ for 0.5 h was used to carry out quenching and tempering of the 40Cr steel. Effect of induction furnace and pit furnace composite heating on the microstructure and properties of the 40Cr steel was studied through microstructure observation, Rockwell hardness and impact property testing, and compared with conventional single furnace quenching heating process. The results show that the hardness obtained by the composite heating process is 29-30 HRC, which is 4±2 HRC higher than that by the conventional heating process, and the data fluctuation is minimal. The composite heating process provides excellent impact properties, and the highest impact absorbed energy of 118 J can be obtained when tempered with water-cooling. The specimen under composite heating process can obtain fine and uniform tempered sorbite. The optimal composite heating process is induction heating to 900 ℃ and then pit furnace isothermal heating at 860 ℃ for 0.5 h, water-quenching, tempering at 580 ℃ for 1.5 h and then water-cooling. It can be inferred that for the quenching and tempering treatment of slender shaft parts, the composite heating of induction furnace and pit furnace has good feasibility. While improving the comprehensive mechanical properties of the materials, the composite heating can greatly shorten the heating and holding time, which is of great practical significance for improving production efficiency, reducing energy costs and improving furnace life.

Key words: induction heating, quenching and tempering, 40Cr steel, microstructure, mechanical properties

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