Aging precipitation behavior of super austenitic stainless steel 654SMO at 900 ℃

doi:10.13251/j.issn.0254-6051.2023.01.012

Abstract

Abstract: Super austenitic stainless steel 654SMO was aged at 900 ℃ for different time. The microstructure of the precipitated phase was observed by scanning electron microscope (SEM) and transmission electron microscope (TEM). The composition and structure of the precipitated phase were analyzed by energy spectrum analysis and selected area electron diffraction. The precipitation kinetics was studied by JMA equation. The results show that the precipitated phases in the super austenitic stainless steel 654SMO are mainly σ phase and Cr₂N phase.During the aging process from 10 min to 1 h,the precipitated phases in the steel is mainly σ phase. The precipitation position of σ phase is grain boundary, non-coherent twin boundary, coherent twin boundary, and finally within grains in the sequence. During the aging process from 2 h to 12 h, the σ phase begin to form needle-like phase in the grain.With the prolongation of aging time, the amount of precipitated phases become more and more.In addition, they interlace with each other and form a network in the grain.After aging for 24 h and 48 h, because σ phase is rich in Cr element and the grain boundary structure is very different between σ phase and austenite phase,Cr₂N phases nucleate on the σ phases in strips or irregular chunks.The precipitation kinetics equation of precipitated phase in the steel 654SMO is X=1－exp(－0.0487t^0.729).

Key words: super austenitic stainless steel, aging, microstructure, precipitated phase, precipitation kinetics

CLC Number:

Zhao Zhengxiang, Li Jingyuan, Liao Luhai, Xu Fanghong, Zhang Wei. Aging precipitation behavior of super austenitic stainless steel 654SMO at 900 ℃[J]. Heat Treatment of Metals, 2023, 48(1): 68-74.

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