Effect of flux compositions on grain refinement in Al-Si-Mg alloy

There are many compositions in fluxes and each composition has different effects on melt treatment. However, the effect of flux compositions on grain refinement fading has not yet been well established. This research is to study effect of different typical chemical compositions in various ratios on grain refinement fading after recycling of return scraps. Al-Si-Mg alloy (A356) was selected for this research and grain refined using 0.2 wt.% of Al-5Ti-1B grain refiners. Each molten alloy was treated with three different fluxes at 1% of aluminum weight. The work was undertaken by recycling the grain-refined castings for four cycles. No grain refiner was added but the same flux was added in each melting process at the same weight ratio. It was found that flux compositions have strong effect on grain size and fading phenomenon of grain refinement. Based on this result, it was found that MgCl2 in flux composition can reduce the fading phenomenon substantially.