Study on Mechanism of Improving Metastable Pitting of Duplex Stainless Steel by Ce2O3-contained Oxide
PANG Zongxu, ZHU Rong, TU Kailu, TANG Tianping, ZHANG Yibo
Beijing Key Laboratory of Special Melting and Preparation of High-End Metals, School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083
Abstract: By means of scanning electron microscope (SEM), atomic force microscopy (AFM), potentiostatic pulse technique (PPT), pitting initiation mechanism of 2205 stainless steel in neutral chloride ion environment caused by oxide was studied. It was found that contact potential difference (CPD) increased sharply at MgO segregation in the MgO-Al2O3 inclusions and CaO enrichment zone in the MgO-CaO-Al2O3 inclusions. The enrichment of CaO was easy to cause the appearance of micro cracks on the surface and the exposure of matrix, which leads to galvanic corrosion. After treated by Ce, the inclusions were transformed into complex inclusions containing Ce2O3·11Al2O3 or Ce2O3·Al2O3. CPD decreased and pitting initiation phenomenon did not emerge. Finally, the pitting initiation mechanism caused by oxides inclusions and mechanism of Ce reacted with inclusion were explained.
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2017, Vol. 31 
