Effects of hydrogen on stress corrosion cracking of Al-8%Mg alloy

Abstract

The susceptibility of the Al-8%Mg alloy to stress corrosion cracking changes with an aging state and reaches to its maximum at the state in which precipitates are distributed the most densely at grain boundaries. Hydrogen penetration reaches to its maximum at the maximum aging state. Hydrogen has the most remarkable effect on stress corrosion cracking at the slightly under-aged state of maximum susceptibility. The fracture of stress corrosion cracking is of an intergranular mode. The smoothed facet of intergranular cracking may be produced by mechanical fracture, because plastic deformation marks and precipitates remain on the facet. Stress corrosion cracks are generated by mechanochemical corrosion and propagated by a combined action of corrosion and hydrogen embrittlement.