The Effect of the Iron Content of an Aluminum Die Casting Alloy on the Rate of Reaction Between the Molten Alloy and H13 Die Steel

摘要

Soldering reactions are commonly observed during high pressure die casting of aluminium alloys. These reactions involve the formation and growth of intermetallic phases at the interface between the solid die steel and the liquid aluminium alloy. It is generally believed that approximately 1 wt. percent Fe is required in the aluminium alloy to reduce soldering. However, the role of iron in the interfacial reaction has not been studied in detail. In this investigation, reaction couples were formed between H13 tool steel and an Al-11Si-2.5Cu melt containing either 0.15 or 0.60wt. percent Fe and held at 610 deg C. The rate of steel removal (by consumption during the reaction) and overall growth of the reaction layer was compared for the two aluminium alloys. It was demonstrated that a higher iron content reduces the consumption of the H13 die steel by the interfacial reaction. Metallographic evidence showed that this is due to a thicker compact (solid) intermetallic layer developed at the interface in higher iron melts. This thick compact layer reduces the diffusion flux of the reactants that are consumed in the formation of intermetallic phases.