Effect of Tensile Deformation and Heat Treatment on the Stress Corrosion Susceptibility of an Al-ZN-Mg Alloy.

摘要

The effect of a series of thermomechanical treatments on the stress corrosion susceptibility of an Al-6.86 w/o Zn-2.35 w/o Mg alloy in a 3.5percent sodium chloride solution was studied by bent beam type stress corrosion tests. The results indicated that for specimens without a room temperature preaging treatment, a 2percent plastic deformation before the final aging at 150C increased the stress corrosion resistance. No such improvement resulted from a 5percent deformation. The difference in the stress corrosion susceptibility for the two treatments was attributed to the difference in the dislocation and precipitate distributions in the matrix in the two cases. For both the undeformed specimens and specimens deformed by 2percent, preaging at room temperature resulted in lower values of stress corrosion time to failure. This reduction in stress corrosion resistance was attributed to incomplete elimination,during aging,of grain boundary solute segregation in the preaged specimens. (Author)