Effect of die-casting conditions on viscoelastic behavior of Mg alloy

Creep and stress relaxation resistance of the most common die-cast Mg alloy AZ91D (Mg-9% Al-1% Zn) are influenced by both casting temperature and injection rate as well as by die temperature and porosity. Relationships between viscoelastic properties of Mg alloy at 150 °C and the parameters of die-casting technology are obtained and presented as simple contour plots (isograms). These properties can be improved by reducing casting temperature and increasing injection rate. When fabricating complicated thin-wall components, castability of the alloy can be diminished due to a fast temperature drop. In this case, casting temperature should be higher, whereas injection rate can be reduced. Porosity seems to be the most important characteristic of die-cast alloy microstructure affecting its viscoelastic properties. Coarse β-phase precipitates do not affect creep and relaxation characteristics of die-cast AZ91D alloy.