The effects of Cu and Mn content and processing on precipitation hardening behavior in Al-Mg-Si-Cu alloy 6022

摘要

In this paper we report on an investigation of the effects of Cu and Mn content on the aging kinetics of aluminum alloys based on the 6022 composition. We varied the Cu content from 0.07 to 0.91 weight percentage and the Mn content from 0.07 to0.60 weight percentage. This study was initiated in order to evaluate the effects of these alloy additions on alloys with application to automotive body parts. Therefore we used the paint bake temperature of current practice (177°C) as the artificialaging temperature. We were particularly interested in the effect of these additions to the early stages of the hardening process, i.e. times of 20 minutes or less. The effect of Mn was minimal on the kinetics of aging. However, Cu had a very large effecton the as quenched hardness (lower) and the kinetics of artificial aging for times less than 20 minutes. We also studied alloys that had significant amount of natural aging. In this case the Cu had a less dramatic effect of increasing the kinetics ofartificial aging.