THE DEPENDENCE OF GRAIN-SIZE ON STRESS DURING DYNAMIC RECRYSTALLIZATION

The steady state grain size during dynamic recrystallisation by grain boundary migration is shown to be simply related to deformation stress for a number of metals and minerals. The data plotted on a scale of grain size (D) divided by Burger's vector (b) against stress (sigma) divided by shear modulus (mu) fills in a remarkably narrow range bounded by loci of form [GRAPHICS] with K = 1 and 10. Models of the dynamic recrystallisation process are developed to show that such a relation can be predicted by considering a dynamic balance between the rate of formation of the deformation substructure and the mean velocity of recrystallising grain boundaries. Hence providing a physical basis for the empirical relation derived from the normalised plot of experimental results.