The welded joints of 3Cr pipeline steel were fabricated with commercial welding wire using the gas tungsten arc welding （GTAW） technique. Potentiodynamic polarization curves, linear polarization resistance （LPR）, ...The welded joints of 3Cr pipeline steel were fabricated with commercial welding wire using the gas tungsten arc welding （GTAW） technique. Potentiodynamic polarization curves, linear polarization resistance （LPR）, electrochemical impedance spectroscopy （EIS）, scan- ning electron microscopy （SEM）, and energy-dispersive spectrometry （EDS） were used to investigate the corrosion resistance and the growth of a corrosion film on the weld zone （WZ）. The changes in electrochemical characteristics of the film were obtained through fitting of the EIS data. The results showed that the average corrosion rate of the WZ in CO2 environments first increased, then fluctuated, and finally de- creased gradually. The formation of the film on the WZ was divided into three stages： dynamic adsorption, incomplete-coverage layer forma- tion, and integral layer formation.展开更多
The cathodic reaction mechanisms in CO2 corrosion of low-Cr steels were investigated by potentiodynamic polarization and galvanostatic measurements.Distinct but different dominant cathodic reactions were observed at d...The cathodic reaction mechanisms in CO2 corrosion of low-Cr steels were investigated by potentiodynamic polarization and galvanostatic measurements.Distinct but different dominant cathodic reactions were observed at different p H levels.At the higher p H level(p H>~5),H2 CO3 reduction was the dominant cathodic reaction.The reaction was under activation control.At the lower pH level(pH<~3.5),H+reduction became the dominant one and the reaction was under diffusion control.In the intermediate area,there was a transition region leading from one cathodic reaction to another.The measured electrochemical impedance spectrum corresponded to the proposed cathodic reaction mechanisms.展开更多
基金financial support from the Natural Science Foundation of China (No. 51371034)
文摘The welded joints of 3Cr pipeline steel were fabricated with commercial welding wire using the gas tungsten arc welding （GTAW） technique. Potentiodynamic polarization curves, linear polarization resistance （LPR）, electrochemical impedance spectroscopy （EIS）, scan- ning electron microscopy （SEM）, and energy-dispersive spectrometry （EDS） were used to investigate the corrosion resistance and the growth of a corrosion film on the weld zone （WZ）. The changes in electrochemical characteristics of the film were obtained through fitting of the EIS data. The results showed that the average corrosion rate of the WZ in CO2 environments first increased, then fluctuated, and finally de- creased gradually. The formation of the film on the WZ was divided into three stages： dynamic adsorption, incomplete-coverage layer forma- tion, and integral layer formation.
基金financially supported by the National Natural Science Foundation of China (No. 51371034)Fundamental Research Funds for the Central Universities (No. 06500118)
文摘The cathodic reaction mechanisms in CO2 corrosion of low-Cr steels were investigated by potentiodynamic polarization and galvanostatic measurements.Distinct but different dominant cathodic reactions were observed at different p H levels.At the higher p H level(p H>~5),H2 CO3 reduction was the dominant cathodic reaction.The reaction was under activation control.At the lower pH level(pH<~3.5),H+reduction became the dominant one and the reaction was under diffusion control.In the intermediate area,there was a transition region leading from one cathodic reaction to another.The measured electrochemical impedance spectrum corresponded to the proposed cathodic reaction mechanisms.
