The Concept of Quality Index and Its Application for Al–Si Cast Alloys

The quality of aluminum–silicon casting alloys is considered to be a key factor in selecting an alloy for a particular engineering application. Deciding upon the right alloy quality thus involves reaching a suitable compromise between numerous factors so as to present the least possible risk with maximum performance in combination with adequate cost-effectiveness. Alloy composition, solidification rate, heat treatment procedures, casting defects, and such microstructural features as grain size and intermetallic phases, are all parameters which closely affect alloy quality since they also influence the mechanical properties of the casting. The development of the quality index concept and quality charts, in particular, in relation to their application to Al–Si casting alloys will be reviewed in this article. Although this paper covers only aluminum alloys, the methodology should also apply to other materials and alloys (iron and steels, Mg alloys, etc.) Cáceres has established the scientific basis for constructing quality indices and plots, and this could be applied to other materials.