| FAN Xue-hua,YU Yong,ZHANG Zi-ru,FENG Zhe,CHEN Li-juan,DONG Lei,ZHANG Lei.Pitting and Repassivation Behavior of 316L Austenitic Stainless Steel under Different Potentials[J],49(7):287-293 |
| Pitting and Repassivation Behavior of 316L Austenitic Stainless Steel under Different Potentials |
| Received:January 10, 2020 Revised:July 20, 2020 |
| View Full Text View/Add Comment Download reader |
| DOI：10.16490/j.cnki.issn.1001-3660.2020.07.036 |
| KeyWord:austenitic stainless steel polarization EIS pitting corrosion repassivation |
| Author | Institution |
| FAN Xue-hua |
1.China Petroleum Engineering & Construction Co., Ltd Beijing Company, Beijing , China |
| YU Yong |
1.China Petroleum Engineering & Construction Co., Ltd Beijing Company, Beijing , China |
| ZHANG Zi-ru |
2.Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing , China |
| FENG Zhe |
2.Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing , China |
| CHEN Li-juan |
1.China Petroleum Engineering & Construction Co., Ltd Beijing Company, Beijing , China |
| DONG Lei |
1.China Petroleum Engineering & Construction Co., Ltd Beijing Company, Beijing , China |
| ZHANG Lei |
2.Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing , China |
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| Abstract: |
| The work aims to investigate the effect of applied potentials on the pitting and repassivation behavior of 316L austenitic stainless steel. Cyclic polarization, potentiostatic polarization and electrochemical impedance spectroscopy tests were selected to study the effect of series potential and mixed potential on pitting sensitivity of 316L austenitic stainless steel. In addition, SEM and XPS were used to observe the pitting morphology and analyze the elemental concentration of passivation film. At 60 ℃, the passive region of 316L austenitic stainless steel in saturated CO2 and 10 g/L NaCl test solution was -0.394~0.168 V, but when the potential was between -0.100~0.168 V, there was a certain current fluctuation, namely metastable pitting zone. The current density of 316L stainless steel in passive region was very small, slightly increasing with the increase of potential and the pit was not observed on the sample surface after polarization. However, the current density of 316L austenitic stainless steel in metastable pitting region was high and obvious pitting appeared on the samples. In the mixed polarization with potential from 0.1 V to -0.1 V, the current density droped sharply and eventually stabilized at a lower current value. Meanwhile, the results of XPS showed that the Cr and Mo concentration increased with the potential transition, but the Fe element was selectively dissolved in this condition. Cr and Mo are corrosion resistance elements, and the existence of the oxides or hydroxides can promote the local repair of passivation film. Therefore, the surface of 316L stainless steel presents repassivation behavior, the stability of the passivation film is enhanced and the corrosion resistance is improved with the transition to low potential. |
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