The effect of solution treatment and artificial aging on the work hardening characteristics of a cast Al–7%Si–0.6%Mg alloy

Al–7%Si–0.6%Mg (D357) alloy castings were heat treated for four different solution treatment times at 540 °C (1, 4, 16 and 64 h) and six different artificial aging times at 160 °C (0, 2.5, 5, 10, 20 and 40 h). Tensile work hardening characteristics were investigated by Kocks–Mecking plots for each specimen. The effects of Si particle morphology (solution treatment) and matrix strength (aging) on Kocks–Mecking (Stage III) work hardening model parameters were studied. It was found that (i) the shearing–bypassing transition in β″ precipitates takes place at or slightly after peak strength, and (ii) solution treatment, i.e., the size and aspect ratio of Si particles, has a profound effect on the Stage III work hardening characteristics of D357.