Effect of holding Al-0.7 wt% Mg in liquid state on removal of double oxide film defects from melt

The effect of holding Al-0.7 wt% Mg alloy in liquid state on elimination of double oxide (bifilm) defects from melt and the mechanical properties of the solidified casting was studied using Weibull statistical analysis and study of the fracture surfaces of tensile test bars. From the results of this study, it can be pointed out that the scattering of UTS values increases during the first 60 min of holding, but decreased afterwards when the melt was held for 250 min. The study of the fracture surfaces and the comparison of the Weibull and results in literature, confirms the theory of formation of bonding between the two layers of double oxide film defects in this alloy after a holding time of 90 min, in a real casting condition. This theory was previously verified in a controlled simulated condition. Some evidence for the formation of bonding between the layers of a double oxide defect was also observed in SEM micrographs.