Effect of Zn/Mg ratios on SCC, electrochemical corrosion properties and microstructure of Al-Zn-Mg alloy

A detailed investigations of Zn/Mg ratios on stress corrosion cracking(SCC), electrochemical corrosion properties and precipitates of Al-Zn-Mg alloy with Zn+Mg ≈ 7 wt% were studied by mechanical, stress corrosion cracking(SCC), electrochemical cyclic polarization together with transmission electron microscopy (TEM) microstructural examinations. It is shown that the strength, SCC and electrochemical corrosion resistance are significantly increased with the decrease of Zn/Mg ratio. The strength of the alloys are significantly increases with the decrease of Zn/Mg ratio, which was attributed to increase the volume fraction of matrix precipitates. The enhance of SCC resistance and electrochemical corrosion properties was attributed to the narrower width of PFZ and low concentration of Zn in aluminum matrix. •Influence of Zn/Mg ratio on microstructure and corrosion properties of Al-Zn-Mg alloy have been investigated.•The number of matrix precipitates increases with the decrease of Zn/Mg ratios.•The strength and stress corrosion resistance are significantly improved with the decrease of Zn/Mg ratios.