SEVERE PLASTIC DEFORMATION TECHNIQUES

There is a considerable interest in developing methods for processing of materials with ultrafine grain si- zes. Widely used methods in refining microstructure are severe/intense plastic deformation techniques, such as torsion straining, equal channel angular (ECA) pressing/extrusion,and accumulative roll bonding (ARB) technique.While the torsion technique has been available for decades,a new torsion system has been developed at DSI for simulation of complex stress states such as combination of shear and compression or shear and tension stress states. The equal channel angular pressing technique is ma- inly used for production of ultrafine grain aluminum alloys,which is aimed at develoment of high strain rate superplasticity.The accumulative roll bonding technique has been applied for the rolling of both aluminum alloy and steels to produce ultrafine gained materials. Three different types of hot compression deformation methods, each with a different number of deforma- tion axis, are introduced in this paper. They are single axis deformation, two axis deformation and three axis deformation.The single axis deformation has us or little restraint such as plane strain type testing and axisymmetric compression testing, the two - axis deformation can be fully restrained or un- restrained, and the three - axis deformation has no restraint. The two - axis restrainsd compression deformation techopue is recommended for loboratory side after comparing the single - axis and the three - axis deformation techniques since the bulk volume of the two - axis restraint compression speci- men can be easily machined into mechanical testing speciments for mechanical property measurement and other studies,and the technique can be aplied to studies of any metallic materials.