Influence of microstructure on hydrogen embrittlement of Al-8%Mg alloy

Abstract

When hydrogen is charged to the Al-8%Mg alloy, a large amount of hydrogen is penetrated only in the age-hardened state, but a small amount is penetrated in the under and over-aged states. The maximum penetration state is nearly agrees with the maximum hardened state. This is attributed to the correspondence of hydrogen penetration to distribution of precipitates owing to preferred penetration into grain boundaries and interfaces of precipitates. The alloy hydrogen-penetrated is embrittled and further susceptible to intergranular cracking. The alloy slightly under-aged is the most embrittled. This is attributed to the predominant relation to grain boundary precipitation. Hydrogen enhances intergranular cracking by facilitating formation of microvoids and cracks at grain boundaries and interfaces of precipitates.