Observations on the Stress Corrosion Cracking of an Al-5% Zn-2.5% MG Ternary and Various Quarternary Alloys,

摘要

Studies were undertaken to test a concept of controlling stress-corrosion crack propagation in Al-Zn-Mg alloys through the use of minor alloying additions of elements known to retard hydrogen ion recombination such as Cd,As,Zr and Cr. Results indicated that the concept was invalid since the minor alloying additions themselves exerted a more profound influence on the grain boundary microstructure. Specifically,the microstructural features of grain boundary particle size and interparticle spacing were found to correlate with stress corrosion susceptibility. Auger electron spectroscope studies also revealed a correlation between the concentration of Zn and Mg within the precipitate-free zone and the susceptibility to cracking. (Modified author abstract)