Effects of nitrogen content and solution treatment temperature on microstructure and hardness of 21-6-9 austenitic stainless steel

doi:10.13251/j.issn.0254-6051.2021.12.012

Abstract

Abstract: In order to investigate the effect of nitrogen content and solution treatment temperature on microstructure and hardness of 21-6-9 stainless steel, three kinds of hot rolled 21-6-9 stainless steel with different nitrogen contents were solution treated at 950, 1000, 1050, and 1100 ℃ for 1 h, respectively, of which the microstructure was observed by optical microscope. Combined with Thermo-Calc thermodynamic calculation, the microstructure of the tested steel was analyzed and the hardness was tested. The results show that ferrite precipitates in the 21-6-9 stainless steel with 0.20%-0.28%N along the rolling direction after hot rolling, and the ferrite in the steel with 0.20%-0.28%N can be eliminated by solution treatment at 950-1000 ℃. When the N content reaches 0.34%, the ferrite no longer appears in the tested steel. With the increase of solution treatment temperature, grain growth occurs in the 21-6-9 stainless steel and the hardness decreases. With the increase of N content, the hardness of the 21-6-9 stainless steel in solution treated state can be significantly increased, while the increasing degree decreases with the increase of solution treatment temperature.

Key words: 21-6-9 stainless steel, solid solution treatment, microstructure, hardness

CLC Number:

TG161

Yan Zhikun, Chen Haitao, Lang Yuping, Qu Huapeng, Feng Hanqiu, Liu Rongpei. Effects of nitrogen content and solution treatment temperature on microstructure and hardness of 21-6-9 austenitic stainless steel[J]. Heat Treatment of Metals, 2021, 46(12): 76-80.

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