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采用动电位极化曲线和电化学阻抗谱结合光学显微镜研究了超级双相不锈钢SAF2507焊接接头经不同温度固溶处理后在高温浓磷酸中电化学行为。结果表明:2507不锈钢固溶处理可以改善原始焊接接头的组织提高其耐蚀性能;其中经950℃固溶处理后的焊接接头自腐蚀电流密度和致钝电流密度较小,极化后的电极表面点蚀较轻;腐蚀行为受电荷转移电阻和有限扩散层的混合控制,符合半无限扩散过程的特征;经950℃固溶处理后焊接接头在高温浓磷酸中形成的钝化膜较为致密。
The electrochemical behavior of super duplex duplex stainless steel SAF2507 welded joints at different temperatures after solution treatment was investigated by using potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS). The results show that the solution treatment of 2507 stainless steel can improve the microstructure of the original welded joint and improve the corrosion resistance of the welded joint. The self-corrosion current density and blunt current density of the welded joint after solution treatment at 950 ℃ are small, The corrosion behavior is controlled by the mixture of charge transfer resistance and limited diffusion layer, which accords with the characteristics of semi-infinite diffusion process. The passivation film formed by high temperature concentrated phosphoric acid after the solution treatment at 950 ℃ is dense.