An analytical method has been used to generate quality index charts for diecasting alloys. The charts have been used to analyze the effect of Si, Cu, Mg, Sr and Mn on the strength and ductility of a range of high-pressure diecasting (HPDC) alloys. The analysis shows that Mg increases the strength without loss in alloy quality, while Cu tends to reduce the alloy quality somewhat. A high level of Si has a strong deleterious effect on the alloy ductility, reducing the alloy quality. The quality of any given alloy is controlled, to a large extent, by Mn and Cr, which refine the Fe-rich phases, and by Sr, which refines the eutectic Si particles. Strontium seems to be more important at low (0.6 percent) levels of Fe, while Mn and Cr seem to be more important at higher (1.5 percent) levels of Fe. The tensile strength of alloys with high (13 percent) Si content seems to be more sensitive to casting defects than that of alloys with lower (7 percent) Si content. The available data on fatigue behavior is discussed.
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