Effect of the chemical composition on the mechanical properties and stress corrosion cracking sensitivities of high-strength Al-Zn-Mg alloy

Abstract

With a view to developing the high-strength Al-Zn-Mg alloy for weld structure, the mechanical properties and stress-corrosion cracking sensitivities have been investigated using the samples containing 1-2% Mg and 4-7% Zn, and under the different conditions of heat treatment. At the same time, the sample with 1.75% Mg and 6.0% Zn was selected as an alloy excelling in the aforesaid both properties. Next, 0.1-0.6% Cu and 0.2-0.6% Ag were added to improve the stress corrosion cracking sensitivity, then the stress corrosion cracking sensitivity was investigated. The authors have confirmed that the addition of Cu and Ag remarkably improves the stress corrosion cracking life, which can be explained by anodic dissolution of the grain boundary precipitates to be restrained, due to the reduction of the potential difference with the matrix.