H2S溶液中316L不锈钢TIG焊接头的腐蚀性能

文中通过极化曲线、交流阻抗、Mott-Schottky曲线、浸泡腐蚀试验等方法对316L奥氏体不锈钢TIG焊接头各区域在不同浓度H₂S溶液中的耐蚀性能进行了研究.极化曲线及交流阻抗结果表明，随着溶液中H₂S浓度的升高，焊接接头各区域的耐蚀性明显降低.另一方面对于相同浓度的H₂S溶液，316L基体的耐蚀性最好，其次是热影响区，焊缝区的耐蚀性最差.Mott-Schottky曲线结果表明，焊接接头在H₂S溶液中的表面钝化膜形成p-n结结构，掺杂浓度高达1022 cm-3，且掺杂浓度随H₂S浓度升高而增大，致使钝化膜防护性能降低.

Corrosion behavior of TIG welded joints of 316L stainless steel in H2S solutions

316 L stainless steel welded joints was prepared by tungsten-arc inert gas (TIG) welding. The corrosion behavior of the TIG welded joints of 316 L stainless steel in different concentrations of H₂S solutions are studied by polarization curves, electrochemical impedance spectroscopy (EIS), Mott-Schottky plots, and immersion corrosion experiments. Polarization curves and EIS results show that the corrosion current densities of the joints significantly increased as the concentration of H₂S solutions increasing, while the corrosion potential decreased. Additionally, for the samples in the same concentration of H₂S solutions, the 316 L base material shows the lowest corrosion current densities, next is the heat-effected zone, the welded zone presents the highest corrosion current densities. Mott-Schottky plots show that the passive films appear a p-n heterojunction, and the donor and acceptor densities reach 1 022 cm^-3, showing a highly defective character of the passive film. The donor and acceptor densities increase with increasing H₂S concentrations. The decreased passivity and the increased doping density affect the protectiveness of the passive film toward corrosion.