Acta Metallurgica Sinica (English Letters) ›› 2021, Vol. 34 ›› Issue (10): 1407-1420.DOI: 10.1007/s40195-021-01240-2

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Effect of Rotation Rate on Microstructure and Mechanical Properties of Friction Stir Processed Ni-Fe-Based Superalloy

Miao Wang1,2, Xing-Wei Huang3,4, Peng Xue3, Chuan-Yong Cui2(), Qing-Chuan Zhang1()   

  1. 1CAS Key Laboratory of Mechanical Behavior and Design of Materials, University of Science and Technology of China, Hefei, 230027, China
    2Superalloy Division, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 110016, China
    3Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 110016, China
    4School of Materials Science and Engineering, University of Science and Technology of China, Hefei, 230027, China
  • Received:2021-02-01 Revised:2021-03-08 Accepted:2021-03-10 Online:2021-10-10 Published:2021-06-02
  • Contact: Chuan-Yong Cui,Qing-Chuan Zhang
  • About author:Qing-Chuan Zhang, zhangqc@ustc.edu.cn.
    Chuan-Yong Cui, chycui@imr.ac.cn;

Abstract:

In this work, friction stir processing (FSP) was applied to the high-strength and high-melting-point Ni-Fe-based superalloy (HT700) for the first time with negligible wear of the stir tool. Different rotation rates were chosen to investigate the effect of heat input on microstructure and tensile properties at different temperatures of friction stir processed Ni-Fe-based superalloy. The results showed that with increasing rotation rate, the percentage of high-angle grain boundaries and twin boundaries gradually decreased whereas the grain size initially increased and then remained almost constant; the difference in tensile properties of FSP samples with rotation rates of 500-700 rpm was small attributing to their similar grain size, but the maximum strength was achieved in the FSP sample with a rotation rate of 400 rpm and traverse speed of 50 mm/min due to its finest grain size. More importantly, we found that the yield strength of all FSP samples tensioned at 700 °C was enhanced clearly resulting from the reprecipitation of γ′ phase. In addition, the grain refinement mechanism of HT700 alloy during FSP was proved to be continuous dynamic recrystallization and the specific refinement process was given.

Key words: Superalloy, Friction stir processing, Grain refinement, Processing parameter