Microstructural and Mechanical Characterization of AM60 Alloy in Semisolid Rheo-die casting with Varying Injection Velocity

This study investigated the changes in microstructure and mechanical properties of AM60 alloy due to injection velocity in semisolid rheo-die casting. Results indicated that as the injection velocity was varied from 0.5 to 9 m/s, the size of primary alpha-Mg particles decreased from 81 to 58 mu m while the shape factor decreased from 2.6 to 1.74, and their distribution became uniform. Similarly, the secondary alpha-Mg phase and divorced eutectic phase were also refined and their distribution became more homogeneous. In addition, when the velocity exceeded 3 m/s, the liquid segregation in microstructures near the product surface significantly reduced. However, as the velocity increased from 0.5 to 3 m/s, the quantity of pores within the product increased from 0.7 to 2.5% and the proportion of large-sized pores also increased. Moreover, the oxide inclusion defect became prominent when the velocity exceeded 3 m/s. The ultimate tensile strength of AM60 product decreased with an increase in injection velocity, the best value of tensile strength was 205 MPa and was achieved at 0.5 m/s. Fracture morphology analysis indicated that pore and shrinkage porosity are the main causes of crack generation and propagation, which affect the overall mechanical property of products. Therefore, they should be carefully controlled by adjusting the injection velocity.

Automated summary

This study investigated the effects of injection velocity on the microstructure and mechanical properties of AM60 alloy in semisolid rheo-die casting. The results showed that increasing the injection velocity resulted in smaller particle size and more uniform distribution of primary alpha-Mg particles. However, excessive velocity led to increased porosity and prominent oxide inclusion defects.