MODELING AND SIMULATION ON MICROPOROSITY FORMED DURING SQUEEZE CASTING OF ALUMINUM ALLOY
铝合金挤压铸造过程微观孔洞形成的建模与仿真

A mathematical model for simulating the microporosity in squeeze casting of aluminum alloy has been developed, in which the heat transfer, solidification shrinkage, feeding flow, pressure transfer, and hydrogen conservation were taken into account. The shrinkage induced flow and the pressure drop in the mushy zone were calculated by solving continuity and momentum equations. A mechanical model was solved for obtaining the pressure transferred into the central area of the casting. By coupling the pressure drop with the pressure transferred into the central area, the pressure distribution in the mushy zone was calculated. Based on the hydrogen conservation equation, the microporosity volume fraction was calculated by referring to the pressure value in the mushy zone. The squeeze casting processes of aluminum alloy under different process conditions were simulated and the simulation results were compared with experimental results. It was shown that the simulation results agree well with the experimental results, and the increases in applied pressure and mould temperature tend to reduce the microporosity in the castings.