Galvanic corrosion associated with SM 80SS steel and Ni-based alloy G3 couples in NaCl solution

Potentiodynamic polarization and electrochemical impedance measurements were used to examine the effects of area ratio Sc/Sa and temperature on the galvanic corrosion behavior between SM 80SS steel and Ni-based alloy G3 exposed to CO2 and NaCl environment. It mainly comprised of the electrochemical characterization such as the self-corrosion potential, the galvanic current and Nyquist plots and so on. Weight loss method was utilized to investigate the corrosion rate of the galvanic couples in high temperature and high-pressure autoclave. After the tests, the surface morphologies of the samples were detected by SEM. In addition, pitting corrosion behavior of anodic material caused by galvanic corrosion was also investigated. The quadratic polynomials corresponded to similar parabolas were fitted to compare the curves of Ig vs. Sc/Sa and CRa vs. Sc/Sa. The results indicate that temperature and Sc/Sa have important effects on the couples of the galvanic corrosion.