Constrained groove pressing and its application to grain refinement of aluminum

The new intense plastic straining technique, named ‘constrained groove pressing’ (CGP), was developed for fabrication of plate-shaped ultrafined grained metallic materials without changing their initial dimensions. The principle of CGP is that a material is subjected to the repetitive shear deformation under the plane strain deformation condition by utilizing alternate pressing with the asymmetrically grooved die and flat die constrained tightly by the cylinder wall. A submicrometer order grain structure was obtained in pure aluminum by utilizing this technique. The grain refinement sequences during pressing were examined by transmission electron microscopy. The enhancement of the mechanical properties of submicrometer order grained pure aluminum fabricated by this technique was comparable to that produced by other intense plastic straining techniques at the similar accumulated strains.