Abstract
It is known that hydrogen in aluminum alloys causes blistering. In this study, the effect of alloying elements on the change of hydrogen content during heat-treatment in Al–Mg based alloys was investigated. As a result, the change of hydrogen content during heat-treatment is affected by not only humidity of atmosphere but also alloying elements. The oxide film on the surface is revealed to prevent the hydrogen from being released to outside. In Al–4mass%Mg based alloys, spheroidal MgO particles can be seen on the surface of the annealed specimens. The number of the MgO particles increases with increasing impurity elements, reducing the shielding effect of oxide film against hydrogen. Therefore, the condensation of hydrogen near the surface after annealing occurs more easily in an Al–Mg alloy of a high-purity than that of an commercial purity.
