固溶温度对00Cr20Ni25Mo6Cu3不锈钢点腐蚀性能的影响

Effect of solution temperature on pitting corrosion resistance of 00Cr20Ni25Mo6Cu3 stainless steels

利用极化曲线、化学浸泡和电化学阻抗测试等方法研究了固溶温度对超级奥氏体不锈钢00Cr20Ni25Mo6Cu3耐点腐蚀性能的影响。并借助金相显微镜（OM）分析了热处理后的组织形貌。结果表明,随着固溶温度的升高,第二相逐渐溶于基体,晶粒也明显长大;腐蚀失重率先降低后增加,在1 200℃时达到最小;交流阻抗谱圆弧半径先增大后减小,即材料耐腐蚀性能先增强后减弱。第二相是导致00Cr20Ni25Mo6Cu3不锈钢耐腐蚀性能下降的主要原因。

The effect of solution temperature on pitting resistance of superaustenitic stainless steels 20 Cr-25 Ni-6 Mo in concentrated chloride media was studied by potentiodynamic scanning（PDS）,chemical immersion test and electrochemical impedance spectroscopy（EIS）.The microstructure of the alloy after heat treatment was observed by optical microscope（OM）.The results show that with the increase of solution temperature,the secondary phases dissolve in the matrix,the grain grows significantly.The rate of weight loss decreases first,and reaches the minimum at 1 200℃,and thereafter,it increases with further increasing solution temperature.Meanwhile,the radius of the EIS capacitive loop increases first and then reduces,signifying that the corrosion resistance of the stainless steels is first enhanced and then weakened.The deterioration of the corrosion resistance of the stainless steel is attributed to the presence of secondary phases.