Comparison of the corrosion behaviour of AZ31B magnesium alloy under immersion test and potentiodynamic polarization test in NaCl solution

This paper reports the comparative evaluation of the corrosion behaviour of AZ31B magnesium alloy under immersion and potentiodynamic polarization test in NaCl solution at different chloride ion concentrations, pH value and exposure time. The specimens were exposed to immersion and polarization environments in order to evaluate their corrosion rates. Empirical relationship was established to predict the corrosion rate of AZ31B magnesium alloy. Three factors, five level, central composite rotatable design matrix was used to minimize the number of experimental conditions. Response surface methodology was used to develop the relationship. The developed relationship can be effectively used to predict the corrosion rate of AZ31B magnesium alloy at 95% confidence level for both the testing. This research work proves a better corrosion resistance of AZ31B magnesium alloy at the alkaline solution than the acidic and the neutral solutions, moreover, low corrosion rate was found at low concentrated solution and higher exposure time respectively.