900℃时效条件下超级奥氏体不锈钢904L的析出相研究

Study on Precipitated Phase in Super Austenitic Stainless Steel 904L Aged at 900℃

采用Factsage热力学软件计算和实验相结合的方法,借助金相显微镜、扫描电镜、透射电镜等检测技术,研究了900℃时效条件下超级奥氏体不锈钢904L热轧板的组织变化情况。结果表明:904L不锈钢在1080℃×40min固溶处理为单一奥氏体组织;900℃时效处理过程中,析出相优先在晶界上形成,随着时效时间延长,析出相数量逐渐增加,尺寸不断增大,最终在晶界上形成网状分布;TEM和EDS表征确定为富Cr、Mo和低Ni的σ析出相,形貌以条状和块状分布为主;热力学计算结果表明904L不锈钢在平衡状态下主要析出相为σ相,与实验结果吻合。

The microstructure evolution of super austenitic stainless steel 904L with different aging time at 900℃ were studied by using the combined method of Factsage thermodynamic calculation software and experiment, with the help of metallographic observation, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. The results show that after 1080 ℃/40 min treatment, the super austenitie stainless steel 904L shows a unitary austenitic microstructure. When aged at 900 ℃ for different time, the precipitated phase formed priority in the grain boundary, and the amount and size of precipitate phase increased with aging time rising, they became into mesh distribution on the grain boundary at last. The results of TEM and EDS show that the precipitated phase was σ, which is mainly rich in Cr, Mo and low Ni and it is distributed in the form of strip and block. Thermodynamic calculation results show that the main precipitated phase of super austenitic stainless steel 904L is σ under the equilibrium state, which agrees with the experimental results.