The characteristics of grain size controlled microstructure and mechanical properties of Al-Si alloy by thixocasting and rheocasting process

In mass production of thixo die casting, there are many disadvantages such as high raw material cost, billet reheating cost, non-destructive control cost, the difficulty of scrap recycling and billet loss during reheating process. On the contrary, in rheo die casting, on-demand slurry like not only cast alloy but also structural alloy can be used and the recycling of scrap is comparatively easy. However, metal composition may be varied and treatment of liquid metal is difficult. Two processes have been adapted to the production of automobile suspension parts. In order to investigate advantages of rheo and thixo die casting process, both processes were compared with optimal process parameters. Microstructure by image analysis and the mechanical properties of produced automobile suspension part are compared between thixo and rheo die casting process. Particularly, the effect of injection conditions on liquid segregation has been investigated for thixo and rheo die casting. The interrelation of microstructure, injection condition and mechanical properties was discussed.