Development of new fiber textures for enhancing mechanical properties of 2024 Al alloy using elevated-temperature constrained groove pressing

Abstract

Constrained groove pressing (CGP) is a type of severe plastic deformation (SPD) employed for sheet metal strengthening. In this investigation, the annealed 2024 Al alloy sheets were employed to conduct the CGP operation at 300 °C temperature and up to three cycles. Afterward, complementary experiments, namely metallography, texture, hardness, and tensile tests were conducted with various deformed and undeformed sheets. As an important observation, a new fiber texture was developed during the third cycle of the CGP operation, affecting the ductility enhancement of this sample besides certain improvement in its ultimate strength. Moreover, in the deformed sheets, existence of hardest orientation, i.e. [111] ‖ RD, in the 1-passed sample with high intensity and creation of some new and soft orientations, i.e. [104] ‖ TD and [326] ‖ ND in the 2-passed specimen and [718] ‖ ND in the 3-passed workpiece, during the CGP process resulted in production of worksheets having specific mechanical properties. It was found that the 1st pass of the CGP process increased the yield strength (YS), ultimate tensile strength (UTS), and hardness of the alloy by 45%, 21%, and 71%, respectively. The worksheets produced via the 2nd and 3rd CGP cycles had higher YS, UTS, and hardness in comparison with the annealed worksheets. The material elongation was improved in the 3rd pass significantly, namely 41%. The precipitations evolutions and the γ-fiber overall intensity are the two most important factors for increasing elongation in the 3-passed specimens. Fractography of the fracture surfaces, also, confirmed these mechanical properties changes in different CGPed samples.