| With the demands for lightness and precision of aerospace equipments, weapons, electronic equipments, the lost foam casting of aluminum (magnesium) alloy becomes a wide used process. However, the porosity defect is largely consisted in the lost foam casting of aluminum (magnesium) alloy, which reduces the castings density and deteriorates the mechanical properties of castings, and limits the further development of lost foam casting. As the pressure solidification could reduce the porosity and shrinkage, and increase the density, combining pressure solidification to lost foam casting process can improve the mechanical properties of the castings.In this paper, the pressure solidification device was designed firstly, and then the influence of different pressures on the porosity, density, mechanical properties and microstructures of the ZL101 aluminum alloy castings was studied, the influence of the pressure increasing rate was investigated also, further the impact of thickness on the properties under different pressure parameters was studied, finally three castings were produced by the lost foam casting under pressure solidification.The results shown that the mechanical properties of the casting were improved, and the density was increased gradually, but the porosity was reduced significantly, with the pressure increasing. The properties of the castings reached a rather constant level over the 0.5MPa pressure.When the pressure increasing rates were changed from 0.003MPa/s to 0.03MPa/s, the castings showed better mechanical properties. Pressure solidification could reduce the sensitivity of mechanical properties to the castings thickness. Shrinkage porosity and misrun defects were more likely to occur in the magnesium alloy castings than in the aluminum alloy, and process parameters of lost foam casting for magnesium alloy under pressure solidification need to be further studied. |
