J. Mater. Sci. Technol. ›› 2021, Vol. 67 ›› Issue (0): 36-49.DOI: 10.1016/j.jmst.2020.06.051

• Research article • Previous Articles     Next Articles

Multi-scale modeling of liquid-metal cooling directional solidification and solidification behavior of nickel-based superalloy casting

Xuewei Yana, Qingyan Xub,*(), Guoqiang Tiana, Quanwei Liua, Junxing Houa, Baicheng Liub   

  1. a School of Aeronautical Engineering, Zhengzhou University of Aeronautics, Zhengzhou 450046, China
    b School of Materials Science and Engineering, Tsinghua University, Key Laboratory for Advanced Materials Processing Technology, Ministry of Education, Beijing 100084, China
  • Received:2020-05-05 Revised:2020-06-07 Accepted:2020-06-19 Online:2021-03-20 Published:2021-04-15
  • Contact: Qingyan Xu
  • About author:* E-mail address: scjxqy@mail.tsinghua.edu.cn (Q. Xu).

Abstract:

Liquid-metal cooling (LMC) process can offer refinement of microstructure and reduce defects due to the increased cooling rate from enhanced heat extraction, and thus an understanding of solidification behavior in nickel-based superalloy casting during LMC process is essential for improving mechanical performance of single crystal (SC) castings. In this effort, an integrated heat transfer model coupling meso grain structure and micro dendrite is developed to predict the temperature distribution and microstructure evolution in LMC process. An interpolation algorithm is used to deal with the macro-micro grids coupling issues. The algorithm of cells capture is also modified, and a deterministic cellular automaton (DCA) model is proposed to describe neighborhood cell tracking. In addition, solute distribution is also considered to describe the dendrite growth. Temperature measuring, EBSD, OM and SEM experiments are implemented to verify the proposed model, and the experiment results agree well with the simulation results. Several simulations are performed with a range of withdrawal rates, and the results indicate that 12 mm·min -1 is suitable for LMC process in this work, which can result in a fairly narrow and flat mushy zone and correspondingly exhibited fairly straight grains. The mushy zone length is about 4.8 mm in the steady state and the average deviation angle of grains is about 13.9° at the height 90 mm from the casting base under 12 mm·min -1 withdrawal process. The competitive phenomenon of dendrites at different withdrawal rates is also observed, which has a great relevant to the temperature fluctuation.

Key words: Multi-scale model, Numerical simulation, Liquid-metal cooling, Microstructure