Aging Behavior of Ultrafine Grained Commercial Al-Mg-Si Alloy Severely Deformed by ARB Process

Abstract

A commercial Al-Mg-Si alloy (6061 aluminum alloy) was used in the present study. The material was solution treated and then severely deformed by accumulative roll-bonding (ARB) process up to 6 cycles corresponding to total equivalent strain of 4.8. Subsequently, the specimens ARB-processed by various cycles were aged at 100°C and 170°C. During aging at 170°C, the increment of hardness of the ARB-processed specimen decreased with increasing the number of the ARB cycles. The hardness of the specimen ARB processed by 6 cycles decreased after aging at 170°C, though the hardness of a conventional solution-treated specimen increased greatly. On the other hand, the hardness of the specimen ARB-processed by various cycles increased significantly after aging at 100°C, and the obtained hardness was quite larger than that of the conventional materials. After aging, the strength and elongation of the solution treated specimen increased and decreased, respectively. The result shows normal tradeoff relationship between strength and elongation. However, in the ARB-processed specimens, the strength as well as elongation increased after aging. Especially, the elongation increased greatly after aging at 100°C. The results suggest that good mechanical properties can be obtained by a combination of grain refinement by severe plastic deformation process and precipitation by aging at low temperature.