Erosion Resistance of Heat-Treated Aluminum Cast Iron to Aluminum Alloy Melt

Abstract

Improvement in the erosion resistance of permanent molds to aluminum alloy melt is required. Since chemically and mechanically stable layer containing aluminum oxides can be formed on the cast irons by aluminum addition and heat treatment, the layer would improve the erosion resistance of the cast iron in the running melt. In this study, cast irons with different aluminum contents were fabricated, then they were heat-treated to form the oxide layer on the surface. The optimum heat treatment conditions to form the stable layer and the erosion behavior of the cast irons were clarified. Heat treatment in air was found to result in the formation of a layer that consists of the oxides, such as Fe 2 O 3 , Fe 3 O 4 and Al 2 O 3 on the cast irons. Based on the castability of the cast irons and morphology of the layer, it was concluded that the addition of 3% aluminum in the cast iron and heat treatment at 1173 K for 10 hours was the most suitable treatment. The heat treatment drastically improved the erosion resistance of the cast iron. The addition of magnesium to the melt temporarily decreased the time to erosion, but increased the time to erosion again when more than 0.75% magnesium.