A Novel Stress Relaxation Modeling for Predicting the Change of Residual Stress During Annealing Heat Treatment

Abstract

Large tensile residual stresses generated during cold working processes could negatively affect the integrity and geometric accuracy of workpieces. The stress relief annealing is one of the fundamental issues in controlling the deformation of the cold-worked part. A novel residual stress relaxation model was proposed to predict the change of residual stress during the annealing process by considering the dislocation evolution mechanism and the plasticity theory. Copper workpieces were rolled with different rolling ratios and annealed under different heating temperatures and heating times. Hole-drilling experiments were conducted to measure the residual stresses for calibrating the proposed model. The calibrated model was then used to predict the change of residual stresses during annealing heat treatment. The results showed that the initial work hardening of workpieces had a great effect on the residual stress relaxation. Higher initial dislocation density hindered the residual stress relaxation during the annealing process. The results provided guidance on optimizing the annealing conditions for residual stress reduction.