目的 研究316L不锈钢TIG焊接接头各区域在不同浓度H2S溶液中的钝化及耐蚀性能差异.方法 在H2S质量浓度为0. 05,0. 1,0. 2,0. 4,0. 8 g/L的H2S溶液中,通过极化曲线、恒电位阶跃、阳极极化、交流阻抗等方法,分别研究316 L奥氏体不锈钢TIG焊接接头的母材区和焊缝区的钝化性及耐蚀性能.结果 随着H2S浓度的增加,焊接接头母材区和焊缝区的钝化性能都所有降低,电化学活性都明显升高,且腐蚀电位逐渐降低,腐蚀电流密度有所增加. 交流阻抗拟合结果显示,母材区和焊缝区的抗腐蚀性能指标( R1+R2 )随着H2S浓度的升高而降低. 此外,在相同浓度的H2S溶液中,焊缝区的腐蚀电位、钝化性能、阻抗都比母材区低,而电化学活性、腐蚀电流密度都比母材区高. 同时,随着H2S浓度的升高,焊缝区与母材区的钝化性能、耐腐蚀性差距逐渐变大. 结论 随着H2S溶液浓度的增加,316L不锈钢TIG焊接接头母材区和焊缝区的钝化性能逐渐降低,耐蚀性下降,且二者耐蚀性的差距逐渐加大. 在相同浓度的H2S溶液中,母材区的耐蚀性比焊缝区好.
Objective To study the difference in the passivation and corrosion behavior of tungsten-arc inert gas ( TIG) welded joints of 316L stainless steel in different concentrations of H2 S solutions. Methods In 0. 05,0. 1,0. 2,0. 4,0. 8 g/L H2 S solutions, the passivation behavior and corrosion resistance of the base material and the welded zone in TIG joints were investigated by polari-zation curves, potential step, potentiostatic polarization, and electrochemical impedance spectroscopy ( EIS) . Results As the con-centrations of H2 S increased, the passivity and corrosion potentials decreased, while the activity and corrosion current densities in-creased. The fitting results of EIS showed that ( R1+R2 ) of the base material and the welded zone in TIG joints decreased with the increased concentrations of H2 S. Meanwhile, the welded zone presented lower corrosion potential, passivity, impedance and higher electrochemical activities and corrosion current densities than the base material at the same concentration of H2 S. Furthermore, the results also suggested that the difference of corrosion resistance between welded zone and base material became significant with the increasing concentration of H2 S. Conclusion As the concentration of H2 S increased, the passivation and corrosion resistance of the base material and the welded zone in TIG joints decreased and the difference of corrosion resistance between them became signifi-cant. The base material presented higher corrosion resistance than the welded zone at the same concentration of H2 S.
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