Effects of Fe, Mn, Cu and Zn on the Technological Properties of AlSi7Mg0.3 (A356) Casting Alloy

Abstract With increasing use of secondary material certain alloying elements may accumulate over repeated melting cycles. To determine the influence of Fe, Mn, Cu and Zn on the technological properties of AlSi7Mg0.3 cast alloy three compositions with varying additions of these elements to a primary alloy melt were produced. Gravity die-casting experiments using a tensile sample permanent mold were conducted, and the cast samples ran through a heat treatment to achieve practical properties. All samples passed through X-ray analysis to minimize the influence of defects on mechanical properties. Specimen for mechanical testing, microscopic analysis and corrosion tests were taken from the cast samples. Quasi-static mechanical properties were measured via tensile and hardness testing, whereas dynamic mechanical properties were determined with high-speed tensile tests. Furthermore, various cyclic fatigue tests are conducted to derive comprehensive S–N curves for each composition. A small increase in R p 0,2 (YS) but a clear decrease in A 5 (Elongation) for quasi-static, as well as for dynamic tensile tests is detected with higher Fe- and Mn-proportions. The further addition of higher amounts of Cu and Zn also affects the mechanical properties in a similar way, albeit at a lower scale. However, Cu significantly aggravates the corrosion properties, whereas no such effect could be detected for Fe and Mn. On the other hand, fatigue properties were not as strongly affected by higher Fe and Mn amounts. In total, the results of this study present a comprehensive overview of the effects that higher amounts of accumulating alloying elements have on the technological properties of AlSi7Mg0.3 cast alloy.