Synergistic Corrosion Mechanism of Cl-and SO32-on 2507 Duplex Stainless Steel
作者
单位
1 Xiamen Branch of Luoyang Ship Material Research Institute、Xiamen 361101、China 2 State Key Laboratory for Marine Corrosion and Protection、Luoyang Ship Material Research Institute (LSMRI)、Xiamen 361101、China 3 Xiamen Key Laboratory of Marine Corrosion and Intelligent Protection Materials、School of Marine Engineering、JiMei University、Xiamen 361021、China
关键词
收录来源
International Corrosion Congress · 第22届国际腐蚀大会
摘要
The synergistic corrosion mechanism of Cl - and SO3 2- on 2507 duplex stainless steel during seawater desulfurization was invest igated using simulation calculations, heat treatment, electrochemical test, SEM, EDS, XRD and XPS. Metallographic observations revealed that the microstructure comsisted of ferrite and austenite phases after solid solution treatment at 1050 °C for 60 min. The electrochemical tests indicated that the hydrolysis of SO3 2- increased the pH of the simulated artificial seawater and inhibited the oxygen depolarization process at the cathode. Moreover, SO3 2- and metal ions formed metal sulphates, reducing th e shielding performance of the passivation film and thus promoting corrosion in the presence of Cl-. Corrosion morphology observation revealed that the corrosion type of 2507 duplex stainless steel in simulated artificial seawater with different concentrations of SO3 2- is selective pitting corrosion, with pitting holes preferentially nucleating and growing in the ferrite region. As the concentration of SO3 2- increases, the number and size of pitting holes increased.