Effects of gap on galvanic corrosion behavior of aluminum alloy A5052/carbon steel SS400 couples in NaCl solutions

Abstract

Galvanic corrosion behavior of Al-Mg alloy A5052/carbon steel SS400 couples with different gaps was investigated in NaCl solutions at various concentrations. The corrosion morphology of the couples differed from each other depending on the gap and NaCl concentration. Steel corrosion was observed as NaCl concentration and/or the gap decreased. When the gap was 10 mm, no corrosion occurred on the SS400 side in all the test solutions, suggesting that anodic dissolution reaction was dominant on the AA5052 side. However, as the gap was decreased, the corrosion of the steel became obvious in the solutions at lower concentrations, although the A5052 also showed localized corrosion. These results indicated that anodic dissolution reaction was generated both on the A5052 and the SS400 under the smaller gap conditions with decreasing the NaCl concentrations. In this study, the effects of gap on the galvanic corrosion behavior were also discussed based on the results of the change in the solution chemistry in addition to galvanic current and potential of the A5052 and SS400 couples.