Modeling and validation of residual stresses induced by heat treatment of AA 7075-T6 samples toward the prediction of part distortion

Abstract

Residual stresses distributions induced by heat treatment of AA 7075-T6 alloy were modeled and simulated. Models of quenching followed by tempering were developed and simulated using the Finite Element Method (FEM). To determine the convection coefficients used in these models, an inverse method coupled with optimization algorithms was developed. The simulated residual stresses distributions were validated by comparing these stresses with those determined experimentally using layer removal and contour methods. The layer removal method consisting into remove successive layers of material by milling was also modeled and simulated using FEM to predict not only the residual stresses, but also part distortion. The predicted part distortion was close to that measured experimentally, which proves the hypothesis that the residual stresses induced by the layer removal method do not affect part distortion. The contour method was used to validate the residual stresses determined by layer removal, and to evaluate the effects of the temperature gradient on the residual stress distribution.