Fine Microstructure Production Through Sandglass Extrusion

摘要

A method of fine and equiaxed microstracture production through Sandglass Extrusion (SE) has been investigated in this paper. In the experiment, a special severe plastic deformation process was conducted in a sandglass die, which is different from Equal-Channel-Angular-Extrusion and looks like cyclic and reciprocating extrusion and compression. A cast Zn-5%Al eutectic alloy with initial grain size about 200 μm and another extruded LY_(12) Al-alloy with initial strong texture have been used as the test materials. The Sandglass Extrusion Processing (SEP) has been described in details. The microstructures after different SEP were observed. The influences of SEP, SE passes and extrusion ratios on the microstructures have been analyzed and discussed. The experimental results showed that the streamlines in test material could be destroyed and uniform equiaxed microstructures with phase particle size of about 1μm could be achieved in Zn-5%Al by SEP at 553K, the m value in superplastic compression test after SEP reached 0.49 under 573K at strain rate of 4.7 x 10~(-2)s~(-1). The initial crystal preferential orientation in extruded LY_(12) alloy was weakened greatly by means of SEP and strong oriented textures disappeared almost.