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 inje ction rate as well as by die temperature and porosity. Relationships betwee n viscoelastic properties of Mg alloy at 150 degrees C and the parameters o f die-casting technology are obtained and presented as simple contour plots (isograms). These properties can be improved by reducing casting temperatu re and increasing injection rate, When fabricating complicated thin-wall co mponents, castability of the alloy can be diminished due to a fast temperat ure drop. In this case, casting temperature should be higher, whereas injec tion rate can be reduced. Porosity seems to be the most important character istic of die-cast alloy microstructure affecting its viscoelastic propertie s, Coarse beta-phase precipitates do not affect creep and relaxation charac teristics of die-cast AZ91D alloy.