RESEARCH NOTES: The influence of quenching temperature on the hardening of pure aluminium quenched to -72°C

The yield stress of pure polycrystalline aluminium quenched from 600°C shows two stages as a function of ageing temperature. A stage Θ1 below a transition temperature θm ( -43°C) in which the yield stress after 150 min of ageing increases with increasing temperature, and a stage Θ2 above θm in which the yield stress decreases with increasing temperature. The effect of quenching temperature on these transition temperatures has been studied and for six quenching temperatures Tq between 475 and 600°C, both stages are observed. The initial yield stress values decrease with decreasing quenching temperature. The transition temperature θm does not change with Tq in the case of super-refined aluminium, but decreases with increasing quenching temperature for less pure metal.