The effect of gate shape on the filling limitation in the semi-solid forging process and the mechanical properties of the products

Abstract

To obtain high quality components with the semi-solid forging process, it is important to obtain a homogeneous distribution of solid particles without liquid segregation. In the closed-die semi-solid forging process, liquid segregation is strongly affected by injection velocity than process parameters such as the pressure and the solid fraction, because the material has to travel a relatively long distance to fill the cavity through a narrow gate before solidification begins. To investigate the effect of gate shape on the filling phenomenon in the semi-solid forging process, two kinds of gate shape system are proposed. A filling test for the two kinds of gate systems was carried out. Therefore, in this study, the optimal injection velocity and die temperature were investigated to fabricate a near-net-shape compressor component called an Al frame. For uniformity of the solid particles, the injection velocity has to be higher than 160 and 370 mm/s to produce sound part without filling defects, in the range of die temperature of from 200 to 300 °C. In addition, the mechanical properties for a forged semi-solid component with a good filling situation were tested with the specimen before and after heat treatment. The forming limits and mechanical properties were discussed in terms of chemical composition and microstructure of the materials used.