Effect of high pressure processing in the formation of castings of aluminum alloys

The effect of high pressure on the formation conditions of aluminum castings has been investigated. It was established experimentally that the crystallization of castings under high mechanical pressure proceeds at a higher temperature difference across the cross section than at atmospheric pressure. The cooling rate of a cylindrical casting in various zones on the section, which is characteristic for cooling alloy in the crystallization range, is determined. The formula for calculating the solidification time of a casting and the time of its holding pressure during piston compression is recommended. The influence of the scale factor on the solidification time of cylindrical castings is considered. It is shown that with increasing height at a constant diameter of the casting, the relationship between the solidification time and diameter of the casting is linear. It has been experimentally established that the solidification coefficient of an alloy depends on its thermophysical properties of the alloy and the applied pressure. Its value increases with decreasing silicon content in the alloy and increasing pressure. The pressure significantly reduces the difference in the values of the solidification coefficient of castings from alloys of different compositions. © Published under licence by IOP Publishing Ltd.