Electrochemical and Stress Corrosion Cracking Behavior of Alpha-Al Bronze in Sulfide-Polluted Salt Water: Effect of Environmentally-Friendly Additives

The stress corrosion cracking (SCC) behavior of α-Al bronze alloy (Cu7 Al) was investigated in 3.5% NaCl solution in the absence and in the presence of different concentrations of Na 2 S under open circuit potentials using the constant slow strain rate technique.Also, the addition of different concentrations of cysteine (cys), and alanine (ala) to the test solution, as corrosion inhibitors, was studied.Increasing the sulfide ions concentration in polluted salt water resulted in a reduction in the maximum stress (σ max ) and an increase in the susceptibility of α-Al bronze towards SCC.The addition of ala and cys to the test electrolyte increased the time to failure by changing the mode of failure from brittle transgranular cracking to ductile failure.Electrochemical tests were performed to assist the interpretation of the SCC data.Electrochemical impedance spectroscopy (EIS) was used to investigate the mechanism of corrosion inhibition.The results support film rupture and anodic dissolution at slip steps as the operating mechanism of the SCC process.Therefore, cys and ala can be considered as potential environmentally-friendly corrosion inhibitors for the SCC of α-Al bronze in 3.5% NaCl solution containing sulfide ions.