Nucleation and growth of recrystallisation in Al-1Mg during thermomechanical processing

A procedure based on quantitative optical microscopy has been used to investigate nucleation and growth of recrystallisation in an Al-1Mg alloy. Hot rolling and plane strain compression tests were employed for this purpose, providing strains within the range 0·2-2·2 and strain rates within the range 2·5-4·9 s -1 , while annealing was carried out at 400°C in all cases. The nucleation kinetics is not site saturated, particularly at low strains, the major discrepancy being observed early during recrystallisaton. However, in practice site saturation is a reasonable approximation. During recrystallisation, the average growth rate decreases continuously. Although concurrent recovery in the unrecrystallised fraction is expected to lead to a decrease in growth rate, the magnitude of the reduction is such that a non-uniform distribution in stored energy is expected to play a significant role.