A new severe plastic deformation technique based on pure shear

Abstract

Pure shear extrusion (PSE) is introduced as a new severe plastic deformation (SPD) technique. The new SPD process provides the possibility of severely deformed metals and alloys in a combined mode of pure and simple shear with the opportunity of changing the ratio of pure to simple shear. The process is fundamentally based on what in the literature is known as pure shear, in which a square deforms to a rhombic alongside its diagonals. The deformation zone in the PSE process is composed of two sections, i.e., upper and lower deformation zones. In the upper deformation zone, an initial square cross section of a sample gradually changes shape to a rhombic while keeping a constant cross sectional area. The constancy of the cross sectional area certifies no velocity change and, therefore, no strain in the direction perpendicular to the cross section of the sample leading to a plane-strain deformation. In the lower deformation zone, the sample gradually gains its initial geometry back by an inverse deformation regarding the upper zone. The constancy of cross section of the sample provides the possibility of repeating the deformation process which makes the PSE a new candidate for SPD processing of metals and alloys. Effective strain is estimated using a geometrical approach. AA1050 aluminum alloy is deformed up to one pass using PSE in order to verify the feasibility of SPD processing by PSE.