Abstract:A novel technology of continuous semisolid extrusion Process (CSEP) was adopted to produce AZ31 alloy structural materials. Effects of technological conditions on the microstructures of AZ31 alloy during CSEP were studied. During the casting process, the non-uniform distribution of microstructures was found in the roll-shoe gap. Microstructure evolution from dendrite to rosette or spherical grains was observed during the casting process by CSEP. The results show that high casting temperature and large cooling intensity can cause non-equilibrium solidification region near the roll surface, large roll-shoe gap width and high cooling intensity can lead to the formation of discontinuous solidification microstructure and slip plane near the shoe surface, which will finally cause the failure of the casting process. The proper casting temperature range of 730-750 ˚C, the roll cooling intensity of 0.4 L/s and the roll-shoe gap width of less than 10 mm are suggested. Under the suggested conditions, the product with diameter of  10 mm of AZ31 alloy with smooth surface and homogeneous striped microstructure is obtained. The average strength of the product after heat treatment reaches 270 MPa, and the elongation is 16%.

Key words: continuous semisolid extrusion process; AZ31 alloy; technological conditions; microstructure; property