氮含量及固溶温度对21-6-9奥氏体不锈钢组织和硬度的影响

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

为了探讨氮含量及固溶温度对21-6-9不锈钢组织和硬度的影响,分别在950、1000、1050和1100℃对3种不同氮含量的热轧态21-6-9不锈钢进行1 h固溶处理,通过光学显微镜观察其组织结构,结合Thermo-Calc热力学计算对试验钢的微观组织进行分析,并对其进行硬度测试。结果表明,0.20%~0.28%N的21-6-9不锈钢热轧后沿轧制方向析出铁素体,且钢中铁素体经950~1100℃固溶处理可消除,当N含量达到0.34%时,试验钢中不再出现铁素体。随着固溶处理温度的升高,21-6-9不锈钢的晶粒组织长大,硬度降低。N含量的增加可显著提高固溶态21-6-9不锈钢的硬度,其增加程度随固溶处理温度的升高而减弱。

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.