Extrudability Improvement of 7000 Series Al Wrought Alloys by Thixoextrusion

The present study discussed extrudability improvement for 7000 series Al wrought alloys by thixoextrusion, with emphasis on controlling thixoextrusion parameters, such as initial ram speed, die bearing length and extrusion temperature of billet in semisolid state. The results of thixoextrusion experiments about microstructures and extrusion pressures were compared with conventional hot extrusion results. The maximum extrusion pressure for thixoextrusion was greatly decreased than that of conventional hot extrusion. This will contribute to extrudability in terms of extrusion pressure, which in turn means that shorter process time is required and smaller extrusion machine can be applied for the same operation. It is also possible to make complex shape components of 7000 series Al wrought alloys, which is not possible by conventional hot extrusion processes. The elongated grains to extrusion direction were generally observed during conventional hot extrusion, while the thixoextruded microstructures were isotropic.