Journal of Northeastern University(Natural Science) ›› 2021, Vol. 42 ›› Issue (12): 1701-1708.DOI: 10.12068/j.issn.1005-3026.2021.12.005

• Materials & Metallurgy • Previous Articles     Next Articles

Investigation on Microstructure Evolution of Aviation Bearing Steel During Carburizing Heat Treatment

JIANG Xia-xia, JIA Tao, WANG Hui, WANG Zhao-dong   

  1. State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819, China.
  • Revised:2021-03-26 Accepted:2021-03-26 Published:2021-12-17
  • Contact: JIA Tao
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Abstract: The microstructure evolution of an aviation bearing steel during carburizing heat treatments was analyzed qualitatively and quantitatively by EPMA and XRD. Results show that after carburizing and direct quenching, the microstructures on sample surfaces and near the surfaces include numerous carbides and a small amount of retained austenite, where the carbides are M23C6and M6C. With increasing carburizing depth, the fraction of carbides decreases and the retained austenite increases. After the secondary quenching, the mass fraction of carbon in austenite and martensite increases. This results in a significant increase of retained austenite fraction after quenching, which reaches 22.7% at 0.1mm of the carburized layer. After twice cryogenic and tempering treatments, the mass fraction of carbon in martensite and austenite decreases. Meanwhile, the carbide fraction increases, leading to the increased hardness of the carburized layer.

Key words: aviation bearing steel; carburizing heat treatment; retained austenite; carbide; XRD analysis

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