Rubber pad-constrained groove pressing process: Experimental and finite element investigation

A new severe plastic deformation (SPD) process named rubber pad-constrained groove pressing (RP-CGP) has been developed for producing ultrafine-grained metallic materials. In this process, repetitive shear deformation conditions are imposed on the sheet material by utilizing asymmetrically grooved die and a polyurethane rubber pad instead of the rigid top die, as in the CGP, through alternate pressing. In this study, commercial pure aluminum sheet was subjected to repetitive deformation using RP-CGP. The process was carried out in two conditions utilizing two dies with different groove angles. Changes in mechanical properties measured by tensile and hardness tests is investigated. Tensile tests show a significant enhancement in mechanical properties including hardness, yield strength and ultimate tensile strength, but the ductility of the alloy reduced by employing this process. The influence of die groove angle on strain distribution throughout the transverse cross-section of specimen was analyzed by the finite element method in 2D plain strain condition using the commercial finite element code ABAQUS. It is shown that a die with a larger groove angle can result in better grain refinement and mechanical properties but cause a less uniform plastic strain distribution throughout the specimen.