Comparative study on the stress corrosion cracking susceptibility of AZ80 and AZ31 magnesium alloys

The stress corrosion cracking (SCC) susceptibility of an as-cast AZ80 magnesium alloy was evaluated using slow strain rate test (SSRT) in air and in 3.5% NaCl solution at various strain rates (10−5 s−1, 10−6 s−1, and 10−7 s−1). Furthermore, to elucidate the effect of aluminum content, the SCC susceptibility of an as-cast AZ31 alloy was also evaluated and compared with the as-cast AZ80 alloy. The SCC susceptibility was quantified using susceptibility indices corresponding to ultimate tensile strength (UTS), strain to failure and time to failure. The SCC susceptibility was found to increase with a decrease in strain rate for both the alloys. The higher SCC susceptibility of the as-cast AZ80 alloy as compared to the as-cast AZ31 alloy was attributed to the higher volume fraction of Mg17Al12 particles, and this was corroborated with the fractographic analysis using a combination of scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS).