Influence of the Wall Thickness on Castability and Microstructure of the QE22 Magnesium Alloy

Abstract

Majority structural elements from magnesium alloys are produced by means of casting. The big and complicated elements are mainly sand cast. The aim of the research was to investigate the influence of wall thickness on the castability and microstructure of modern magnesium alloy with RE and Ag additions – QE22. Eight 145x98mm plates have been cast for the research. Their designed thickness was equal: 0.5mm, 1mm, 1.5mm, 2mm, 3mm, 4mm, 5mm as well as 6mm. The parameters of microstructure constituents in each cast has been estimated quantitatively. The critical wall thickness, at which liquid alloy fill the mould cavity completely, is equal 4mm. With decreasing wall thickness, percentage of filled cavity is decreasing linearly. Mean area of grain flat section increased 7 times in the thickest plate (from 501μm2 to 3773μm2). The volume fraction of eutectics as well as alloy hardness decreased in the thickest plate.