Static recrystallisation and hot strength of Al-1Mg during thermomechanical processing

The kinetics of static recrystallisation of an Al-1Mg alloy has been investigated by rolling slabs of tapered and uniform thickness, and by plane strain compression (PSC) tests at 400°C for a wide range of strains (0·03-2·2) and strain rates (0·25-25 s -1 ). The through thickness gradients in recrystallisation observed in hot rolled and annealed slabs are discussed. Recrystallisation follows an Avrami type of kinetics closely, taking place without hindrance from second phase particles and leading to equiaxed recrystallised grains, finer than the original grain size in most cases, with a critical deformation condition below which no discontinuous recrystallisation can occur. While the recrystallisation behaviour in tapered and uniform thickness slabs is similar, comparison of the results from rolling and PSC indicates that PSC leads to faster recrystallisation kinetics than rolling, when the same average rolling conditions are used in PSC test simulations. The constitutive equations are determined and a comparison of calculated rolling loads using Sims' theory and measured values, indicates good agreement.