IMPROVING THE SOUNDNESS OF Al-Mg-BASED CASTINGS THROUGH CHEMICAL INOCULATION AND PROCESS OPTIMIZATION

Al-Mg-based alloys are non-heat treatable alloys with an excellent combination of specific strength and ductility, thus having a great potential for automotive applications. However, they suffer from poor castability due to a long freezing range and high oxidation tendency, which makes it challenging to obtain sound castings through shape casting. This study aimed to improve the castability of Al-6Mg alloy by adding chemical inoculations and optimizing processing conditions. The results indicated that the addition of a small amount of Al2Ca resulted in a cleaner melt, with a slight increase in flow length. Moreover, the co-addition of Al2Ca and Ti-based inoculants in the Al-6Mg base alloy induced a further increase of similar to 20% in flow length. Similarly, separate or co-addition of Al2Ca and Ti-based inoculants significantly mitigated the hot tearing of the base alloy. The improved castability was attributed to enhanced oxidation resistance and grain refinement. Additionally, these alloys have shown better fluidity when melted and held in an electric furnace than in an induction furnace. The study also revealed that molten aluminum alloys' cleanliness can be achieved through active degassing or passive degassing, as both processes remove oxide inclusions. [GRAPHICS] .