Influence of temperature and alloying elements on fluidity of Al-Si alloys

The goal of the work is to study the influence of casting temperature and four alloying elements: Mg, Ti, Fe and Sr, on fluidity of Al-7wt.% Si alloys. The fluidity of the alloys was measured using a fluidity mold produced by N-Tec Ltd., U.K. The experiments were designed using three orthogonal L-8 Taguchi matrices. Each of the four alloying elements and the casting temperature was an independent variable with two levels. Three interactions between the variables were identified and analyzed. The two levels of Mg were 0.003wt.% and 0.45wt.%; Ti levels were 0 and 0.2wt.%, Fe levels were 0.006wt.% and 0.24wt.%, and Sr levels were 0 and 0.023wt.%. Superheats were 70 degrees C and 130 degrees C over the respective liquidus temperatures of the experimental alloys. The main effect of each of the independent variables on the fluidity was quantified and Analysis Of Variance (ANOVA) was performed on the experiment matrix. The results were verified and validated to ensure robustness of the experiment design. The results of the Taguchi design of experiments show that casting temperature has the most pronounced influence on fluidity of the molten metal. Among the alloying elements chosen, only Mg has an appreciable effect on fluidity. Increasing Mg in the melt from 0.003wt % to 0.45wt.% decreases the fluidity of the molten metal.