Effect of test method on transition from multiple to single peak dynamic recrystallization

The effect of test method on the transition from multiple to single peak dynamic recrystallization is reviewed. Data obtained from tension, compression, and torsion tests are used to evaluate the dependence of the peak and recrystallization strains on the peak stress. It is shown that the intersection stress at which the peak and recrystallization strains are equal depends on the type of test employed. Thus, it does not conform to the critical transition stress which distinguishes between grain refinement (and single peak flow) on the one hand, and grain coarsening (and multiple peak flow) on the other. The discrepancy arises because factors such as flow localization, stress gradients, friction, and the difficulty of determining the surface shear stress from torque data all affect the peak and recrystallization strains, thus modifying the intersection stress.