Flow Stress Evolution in Further Straining of Severely Deformed Al

Abstract

To investigate the flow stress evolution in further straining of severely deformed Al sheets, a comprehensive model which considers both mechanical and metallurgical alterations is needed. In this study, constrained groove pressing (CGP) as a severe plastic deformation method, and a flat rolling process for further straining are utilized. Using basic mechanical models, strain and strain rate were calculated for this process. Dislocation density and flow stress evolutions were predicted by utilizing initial mechanical data, considering the ETMB (Y. Estrin, L. S. Toth, A. Molinari, and Y. Brechet) dislocation density model. Based on these model predictions, the combination of the CGP process with a further rolling process results in higher flow stresses than repeating the specific process discretely. This phenomenon can be attributed to the ability of the rolling process to produce a greater strain rate, which, in turn, leads to the higher flow stresses. Thorough data from the mechanical tests as well as X-ray diffraction profiles strongly support the validity of the model in the prediction of flow stress and dislocation density, respectively.