An investigation on the electrochemical behavior of the base and weld metals of the inner wall of anL245NB/316L bimetallic composite pipe in carbon dioxide (CO2-saturated and CO2-free environmentswith different S2-concentrations) was conducted using potentiodynamic polarization andelectrochemical impedance spectroscopy (EIS) techniques. Results demonstrated that theelectrochemical reaction rate showed an increasing trend with increasing S2-concentration, and CO2 andS2-synergistically accelerated the electrochemical reaction rate when the concentration of S2- was lowerthan 0.1 mol/l. For the weld metal, however, the electrochemical reaction rate decreased due to thesynergistic inhibition effect of CO2 and S2- when the concentration of S2- was increased to 0.5 mol/l. Thecorrosion resistance of the weld metal was significantly lower than that of the base metal under the sametesting conditions..
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