An investigation of hydrogen-induced hardening in 7075-T6 aluminum alloy

The effect of hydrogen on the hardness of 7075-T6 aluminum alloy was investigated after experiments conducted on specimens that hydrogen charged under different cathodic charging conditions. Hardness measurements revealed that the introduction of hydrogen caused hardening on the surface of 7075-T6 aluminum alloy. The severity of the hardening increased with either cathodic current density or charging time. Further charging increased the depth of the hardened region of 7075-T6 aluminum alloy. Transmission electron microscopic observations of the hardened hydrogen-enriched layer revealed an increase in dislocation density. Aging after charging can result in either complete or partial recovery of hardness depending on the charging conditions applied to the material.