Effect of solution heat treatment on the age hardening capacity of dendritic and globular AlSi7Mg0.6 alloys

The effect of solution heat treatment on the age hardening capacity of dendritic and globular AlSi7Mg0.6 alloys was investigated in the present work to find out if solution treatment times are in fact shorter for rheocast parts. The morphology of the alpha-Al matrix, whether dendritic or globular, has no effect on the response of the alloy to T6 treatment. A solution treatment at 540 degrees C for 2 h suffices to fully solutionize the Mg and Si and the age hardening capacity of the AlSi7Mg0.6 alloy is impaired when it is 1 h or shorter. This is true for both dendritic and globular alloys. The expected favourable impact of the globular structure on the solution treatment times is believed to be offset by the relatively coarser structure in the globular alloy with respect to its dendritic counterpart.