This study was carried out to characterize thixoextruded AZ31 Mg alloy in terms of its symmetric behavior through the optical microscope, electron back scattering diffraction and mechanical test. The elongated grains to the extrusion direction were generally observed during hot extrusion, while the thixoextruded microstructures were isotropic. Texture of hot extruded bar showed the strong fiber component, while that of thixoextruded bar was random distribution. The aspect ratio of hot extruded bar was irregular at each position. On the contrary, the aspect ratio of thixoextruded bar was almost uniform below 2 at each position.

No abstract

An attempt has been made to investigate feasibility of thixoextrusion for AZ31 Mg wrought alloy through simple partial remelting. Microstructural evolution of AZ31 Mg wrought alloy for thixoextrusion was investigated as functions of isothermal holding temperature and time in the partially remelted semisolid state. The interesting point of this study was that the thixotropic structures of AZ31 Mg wrought alloy without additional pretreatment could be obtained through simple partial remelting. The uniform average grain size and liquid fraction according to the isothermal holding time were very important for the thixoextrusion. Because, it is must be considered on actual extrusion time. The liquid fraction was increased with increasing isothermal holding temperature and time. But, the liquid fraction was almost uniform after 10 min. The average grain size was decreased with increasing isothermal holding temperature. On the other hand, as the holding time increased, the average grain sizes were uniform at 615 and 622. This phenomenon is very useful for thixoextrusion in terms of process control such as actual extrusion time.

No abstract