含Ce S31254超级奥氏体不锈钢析出相析出行为及耐蚀性

Precipitation of Second Phase and Its Effect on Corrosion Resistance of Ce-containing S31254 Super Austenitic Stainless Steel

采用扫描电镜(SEM)及电化学测试,研究了S31254-Ce超级奥氏体不锈钢固溶、时效处理后第二相的溶解、析出行为及耐蚀性能。结果表明:1250℃保温120 min后,S31254-Ce试样中析出相可完全回溶。800~900℃时效处理后,S31254-Ce不锈钢均有析出相析出,第二相优先析出于晶界。随着温度升高,840℃以上时效处理后,析出相也逐渐在晶内析出,且数量逐渐增多。860℃时效处理过程中,随时效时间延长,晶内细小点状析出相尺寸逐渐增大,晶内析出相渐渐呈现网状结构。S31254-Ce不锈钢固溶处理后试样的耐蚀性最好。随时效温度提高,析出相越多,S31254-Ce不锈钢的耐蚀性能越弱。时效温度为840~900℃时,对应材料的耐蚀性能的下降幅度增加。

The dissolution and precipitation behavior of the second phase and corrosion resistance of S31254-Ce super austenitic stainless steel after solid solution and aging treatment were studied by scanning electron microscope(SEM) and electrochemical test. The results show that the precipitates in S31254-Ce stainless steel can be completely redissolved after heated at 1250 ℃ for 120 min. After aged at 800-900 ℃, particulates of second phase were precipitated in S31254-Ce stainless steel preferentially along grain boundaries. With the increase of aging temperature up to above 840 ℃, the particulates gradually precipitated within the grain, and the number of precipitates gradually increases. During the aging treatment at 860 ℃, with the extension of aging time, the size of the fine dot-like precipitates within the grain gradually increased, and the intragranular precipitates gradually formed a network-like morphology.S31254-Ce has the best corrosion resistance after solid solution treatment. With the increased of aging temperature, the number of precipitates of S31254-Ce stainless steel increased and therewith the corrosion resistance of the steel decreased. After aging at 840-900 ℃, the degree of the corrosion resistance deterioration of S31254-Ce stainless steel increased.