Heat Treatment of Metals ›› 2023, Vol. 48 ›› Issue (2): 110-116.DOI: 10.13251/j.issn.0254-6051.2023.02.017

• PROCESS RESEARCH • Previous Articles     Next Articles

Effect of deformation and cooling rate on transformation characteristic and nanoscale precipitation in a low carbon Nb micro-alloyed steel

Liu Yanqiang1, Yang Hao2, Zhang Zhijun1, Jia Shujun3, Han Pengbiao4   

  1. 1. HBIS Group Wusteel Company, Pingdingshan Henan 462500, China;
    2. HBIS Materials Technology Research Institute, Shijiazhuang Heibei 050018, China;
    3. Institute of Structural Steels, Central Iron and Steel Research Institute Co., Ltd., Beijing 100081, China;
    4. School of Materials Science and Engineering, Hebei University of Scienceand Technology, Shijiazhuang Heibei 050018, China
  • Received:2022-09-02 Revised:2022-12-12 Online:2023-02-25 Published:2023-03-22

Abstract: Effects of austenite recrystallization and unrecrystallization structure on continuous cooling transformation behavior of low carbon Nb micro-alloyed steel were studied by Gleeble 3800 thermal simulator, and the nano precipitation behavior of Nb(C,N) at different deformation temperatures and cooling rates was analyzed. It is found that the plastic deformation in un-recrystallization region of austenite accelerates the ferrite transformation and the ferrite transformation zone is enlarged. The deformation also refines the ferrite grain size. Compared with the single-pass deformation at recrystallizing 1050 ℃, the second deformation in the unrecrystallized zone can promote the precipitation of Nb(C, N), and the precipitation of Nb(C, N) at 910 ℃ is the largest, followed by that at 850 ℃. The increase of cooling rate can inhibit the precipitation of Nb(C, N) in austenite, but can promote its precipitation in ferrite. And the size of precipitates is refined with the increase of cooling rate. When the cooling rate reaches 10 ℃/s, the nucleation of precipitation is totally inhibited during cooling process.

Key words: Nb micro-alloyed steel, deformation, cooling rate, phase transformation, nano precipitation

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