Heat Treatment of Metals ›› 2024, Vol. 49 ›› Issue (11): 138-142.DOI: 10.13251/j.issn.0254-6051.2024.11.020

• PROCESS RESEARCH • Previous Articles     Next Articles

Effect of isothermal treatment below Ms point on microstructure of 15NiCuMoNb5 steel

Zhao Qian1, Zhang Yaran2, Qiao Zhixia1, Dong Ji3, Zhang Junping4   

  1. 1. School of Mechanical Engineering, Tianjin University of Commerce, Tianjin 300134, China;
    2. Material Science Research Center, Xingtai University, Xingtai Hebei 054001, China;
    3. School of Mechanical Engineering, Tianjin Sino-German University of Applied Sciences, Tianjin 300350, China;
    4. Product Institute of Tianjin Pipe Co., Ltd., Tianjin 300301, China
  • Received:2024-06-10 Revised:2024-09-28 Online:2024-11-25 Published:2025-01-09

Abstract: Microstructure and precipitates of 15NiCuMoNb5 steel after isothermal treatment at different temperatures below the Ms point were analyzed by using scanning electron microscope (SEM) and transmission electron microscope (TEM). The results show that when isothermally treated at 370 ℃, M-A islands mainly exhibit a micro-sized long-striped morphology, and the precipitated phases are mainly M3C and Cu-rich phases. After isothermal treatment at 310 ℃, the M-A island is dominated by traditional bulk morphology, and the precipitated phases are mainly spherical Nb-rich carbides. The difference of M-A island morphology and precipitated phase mainly depends on the difference of carbon diffusion rate and driving force of precipitated phase at different temperatures.

Key words: 15NiCuMoNb5 steel, M-A island, precipitated phase

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