机械合金化及热压烧结制备Fe-Cr-Mn基超细晶奥氏体不锈钢研究

采用高能研磨诱导的机械合金化方法制备了Fe-Cr-Mn基不锈钢合金粉末;对机械合金化粉末分别进行了退火和热压烧结,分析了退火过程中的相变规律,并对热压烧结获得的奥氏体不锈钢进行了组织和耐蚀性能研究。结果表明:机械合金化获得的不锈钢合金粉由亚稳态的纳米晶铁素体构成;退火/热压烧结处理后,铁素体逐渐转变为热力学上更加稳定的奥氏体,相变温度介于498℃到730℃之间;对机械合金化16 h的合金粉末在900℃、200 MPa条件下热压烧结1h获得了Fe-Cr-Mn基奥氏体不锈钢,其平均晶粒尺寸为亚微米级且表现出高硬度和良好的耐蚀性能,其HV硬度值约为5350 MPa、自腐蚀电位和自腐蚀电流密度分别为–0.28 V和1.43×10^-9A·cm^-2。

Study on formation mechanism, microstructure and corrosion resistance of Fe-Cr-Mn-based ultra-fine grain austenitic stainless steel

Fe-Cr-Mn-based stainless steel alloy powder was prepared by mechanical alloying method, which is induced by high energy milling. The milled powders were respectively annealed and sintered via hot pressing sintering method, and the phases evolution, microstructure and corrosion resistance were respectively analysed. It is found that the Fe-Cr-Mn-based stainless steel alloy prepared by mechanical alloying is mainly composed of metastable nanocrystalline ferrite phase. After annealing or hot pressing sintering, ferrite phase will transform into austenite phase, and the transformation temperature range from 650 °C to 700 °C. The powder milled for 16 h is hot pressed at 900 °C and 200 MPa for 1 h for bulk alloy. The average grain size of pressed bulk alloy is submicron, which displays high hardness and good corrosion resistance. The hardness, polarization voltage and polarization current are respectively 535 HV, -0.28 V and 1.43×10_^-9 A.cm_^-2.