细晶高氮奥氏体不锈钢的机械合金化热处理工艺研究

Study on Mechanical Alloying and Heat Treatment Process of Fine Grain and High Nitrogen Austenitic Stainless Steel

通过混合Cr_2N和Fe-Cr合金粉达到Fe-23%Cr-1%N粉末比例,并在氩气气氛下进行了球磨。在真空不锈钢管中将Fe-23%Cr-1%N粉末加热至800℃并固化,再将固化材料加热至900~1200℃实现奥氏体化,最后进行不保温淬火。结果表明:试样在小于1050℃热处理后的组织为马氏体,但经高于1100℃热处理后可形成稳定的奥氏体组织以及少量的Cr_2N。由于氧化物弥散分布在钢内,基体晶粒保持细小,钢的屈服强度高达1.1 GPa,伸长率达到30%,如此高的强化效应是氮的固溶强化和细晶强化共同作用的结果。

The proportion of Fe-23%Cr-1%N powder was achieved by mixing Cr2N and Fe-Cr alloy powder, and the ball milling was carried out under argon atmosphere. Fe-23%Cr-1%N powder was heated to 800 ℃ in a vacuum stainless steel tube and then solidified. The solidified material was heated to 900-1200 ℃ to realize the austenifizing. Finally, the zero time holding quenching was carded out. The microstructure of the sample is martensite after heat treatment below 1050 ℃, but the stable austenite microstructure and a small amount of Cr2N can be formed after heat treatment above 1100 ℃. Because the oxide is dispersed in the steel, matrix grains remain small, the yield strength of the steel is as high as 1.1 GPa, and the elongation reaches 30%. Such a high strengthening effect is the result of solid solution strengthening and fine grain strengthening.