Abstract
A compressive torsion process that is one of the severe plastic deformation processes was applied to a commercial pure aluminum in order to obtain fine grain. In the compressive torsion processing the material was subjected to simultaneous compressive and torsional loading without change in its shape. The possibility of grain refinement and the effects of process conditions on the refinement were investigated by changing deformation temperature, compressive pressure, torsional cycle and torsional speed. Very fine grains around several microns were obtained by the compressive torsion process. However the grain refinement was not uniform in the specimen, the fine-grained region was concentrated in peripheral parts of the operating die. Decreasing processing temperature and increasing torsional cycle are effective to decrease grain size and extend finer grain area. The compressive pressure does not influence grain size and finer grain area. Increasing torsional speed enlarges grain size because of rise in temperature due to deformation heat generated in processing.
