Acta Metallurgica Sinica (English Letters) ›› 2022, Vol. 35 ›› Issue (11): 1837-1848.DOI: 10.1007/s40195-022-01413-7

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Interfacial Oxides Evolution of High-Speed Steel Joints by Hot-Compression Bonding

Wei-Feng Liu1,2, Bi-Jun Xie1, Ming-Yue Sun1(), Bin Xu1, Yan-Fei Cao1, Dian-Zhong Li1()   

  1. 1 Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 110016, China
    2 School of Materials Science and Engineering, University of Science and Technology of China, Shenyang, 110016, China
  • Received:2022-01-10 Revised:2022-02-04 Accepted:2022-02-22 Online:2022-11-10 Published:2022-05-21
  • Contact: Ming-Yue Sun, mysun@imr.ac.cn; Dian-Zhong Li, dzli@imr.ac.cn

Abstract:

The interfacial oxidation behavior of Cr4Mo4V high-speed steel (HSS) joints undergoing hot-compression bonding was investigated by using optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). In the heating and holding processes, dispersed rod-like and granular $\delta - {\text{Al}}_{{2}} {\text{O}}_{{3}}$ oxides were formed at the interface and in the matrix near the interface due to the selective oxidation and internal oxidation of Al, while irregular Si–Al–O compounds and spheroidal SiO2 particles were formed at the interface. After the post-holding treatment, SiO2 oxides and Si–Al–O compounds were dissolved into the matrix, and $\delta - {\text{Al}}_{{2}} {\text{O}}_{{3}}$ oxides were transformed into nanoscale $\alpha - {\text{Al}}_{{2}} {\text{O}}_{{3}}$ particles, which did not deteriorate the mechanical properties of the joints. The formation and migration of newly-formed grain boundaries by plastic deformation and post-holding treatment were the main mechanism for interface healing. The tensile test results showed that the strength of the healed joints was comparable to that of the base material, and the in-situ tensile observations proved that the fracture was initiated at the grain boundary of the matrix rather than at the interface. The clarification of interfacial oxides and microstructure is essential for the application of hot-compression bonding of HSSs.

Key words: Hot-compression bonding, High-speed steel, Interfacial oxides, Interface healing, Mechanical properties