Investigation of the T4 and T6 Heat Treatment Cycles of Semi-Solid Processed Aluminium Alloy A356

ABSTRACT

The heat treatment cycles that are currently applied to semi-solid processed components are mostly those that are in use for dendritic casting alloys. These heat treatments are not necessarily the optimum treatments. It is shown that a decrease of the solution treatment time at 540oC from 6 hours to 1 hour does not alter the T4 or T6 tensile properties of the SSM processed A356 alloy. Slightly better impact properties are obtained with the shorter solution treatment. This could lead to time and energy savings. Natural aging prior to artificial aging causes the time-to-peak-hardness to be longer compared to the time when only artificial aging is used. Quenching after solution treatment in water at 70oC results in slightly lower tensile properties than after quenching in water at 25oC. The magnesium content of alloy A356 has a significant influence on the T4 and T6 properties of the alloy.