Abstract:

This paper examines the effects of selected heat treatment processes on the strength and hardness of hot rolled aluminium alloys, namely 2SR, 3SR and 8SR. Three heat treatment processes – annealing, solid solution heat treatment and precipitation heat treatment, are carried out on the alloy samples and their effects on the samples are evaluated by subjecting the samples to tensile and hardness tests before and after heat treatment. The results indicate an increase in hardness with 2SR aluminium alloy after annealing and solution heat treatment processes, and a drop in this property upon subjecting the sample to precipitation annealing, implying that the 2SR aluminium alloy can be better hardened by both annealing and solution heat treatment processes. On the other hand, precipitation heat treatment softens the alloy. This trend is equally applicable to 8SR sample but with a total deviation from this trend with 3SR sample, in which hardness decreases with each heat treat process. The results also suggest aluminium alloys 2SR and 8SR can be better hardened by both annealing and solution heat treatment processes and softened by precipitation hardening. However, 3SR alloy cannot be hardened by any of the heat treatment processes.