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采用机械合金化、渗氮以及粉末冶金压制-烧结工艺制备了0Cr18Mn12Mo3N高氮奥氏体钢。结果表明,用机械合金化和渗氮相结合工艺获得的近球形高氮钢粉末,具有良好的压缩性和成形性,在650 MPa压制力下压坯的相对密度高达76.2%。随着烧结温度的提高,粉末压坯烧结体的密度持续增加,氮含量则不断降低;当温度提高到1250℃时,烧结方式以液相烧结为主,烧结2 h足够使粉末致密化过程完成,此时可获得相对密度为97.2%,氮含量高达0.80wt%的烧结体,继续增加烧结温度对烧结体密度增加作用不大,却会造成氮含量急剧降至不能维持奥氏体单相组织。烧结体经1150℃×1.5 h固溶处理水淬冷却后获得全部奥氏体组织,且奥氏体晶粒细小,其屈服强度和抗拉强度分别达到598 MPa和882 MPa,显著优于传统粉末冶金高氮奥氏体钢。
0Cr18Mn12Mo3N high nitrogen austenitic steel was prepared by mechanical alloying, nitriding and powder metallurgy pressing-sintering process. The results show that the near-spherical high nitrogen steel powder obtained by the combination of mechanical alloying and nitriding has good compressibility and formability. The relative density of the green compact reaches as high as 76.2% under the compressive force of 650 MPa. With the increase of sintering temperature, the density of powder compact sintered body continuously increases and the nitrogen content decreases continuously. When the temperature is increased to 1250 ℃, the sintering method is mainly liquid phase sintering, and sintering for 2 h is enough to make the powder densification process complete , At this time can get a relative density of 97.2%, nitrogen content as high as 0.80wt% of the sintered body, continue to increase the sintering temperature of the sintered density does not increase, but will result in a sharp decrease in nitrogen content can not maintain austenite single phase structure . After sintered at 1150 ℃ for 1.5 h, the sintered austenite was obtained by quenching with solution treatment. The austenite grain size was small and the yield strength and tensile strength reached 598 MPa and 882 MPa, respectively, which were significantly better than that of the conventional powder Metallurgical high nitrogen austenitic steel.