Influence of annealing temperature on the baking response and corrosion properties of an Al-4.6 wt% Mg alloy with 0.54 wt% Cu

Abstract

The effect of different thermo-mechanical processing parameters on the baking response, and intergranular corrosion (IGC) resistance of an Al-4.6 wt% Mg-0.54 wt% Cu alloy was investigated. It has been shown that the high temperature anneal at 530 degrees C resulted in superior baking response of pre-deformed material after short annealing at 140-180 degrees C, compared to the annealing at 280 degrees C. Specimens predeformed 2% had positive baking response for both initial annealing temperatures, however, pre-deformation of 5% induced softening during the baking treatment of the specimens annealed at 280 degrees C. Prior to sensitization of 7 days at 100 degrees C, specimens at all stages of thermo-mechanical treatment were IGC resistant. After the sensitization specimens that underwent annealing at 530 degrees C remained IGC resistant, but specimens that underwent annealing at 280 degrees C became IGC susceptible. Better corrosion properties and baking response are related to the higher Cu content in solid solution after annealing at 530 degrees C than at 280 degrees C.