The Effects of Solidification under Pressure on the Porosity and Mechanical Properties of A206-T6 Cast Aluminum Alloy

The mechanical properties of aluminum alloy castings are severely affected by porosity. Previous results showed that solidification under pressure could reduce the size of the hydrogen/gas porosity and improve the mechanical properties. In the current study, the effects of solidification under pressure on the porosity and mechanical properties of aluminum alloy A206-T6 were determined. Wedge shape castings were produced in chemically bonded sand molds. The wedge shape provides directional solidification, various section sizes and a range of cooling rates. The results showed an increase in ultimate tensile strength by 17-19% and elongation 112-120% due to a decrease in porosity of 79-83% and increase in density by 2.8-2.9% for castings solidified under pressure. Density was significantly increased with the application of pressure during solidification, but density did not show a good correlation with tensile strength or elongation. The mechanical properties of castings solidified under pressure were compared with the HIPed casting and it could be concluded that for A206-T6 alloy the solidification under 10 atmospheres of applied pressure could result in similar equivalent properties of HIPed casting.