QUALITY INDEX FOR ALUMINUM ALLOY CASTINGS

Tensile testing along with nondestructive methods has been traditionally used to assess the quality of cast Al alloys. However, clear guidelines on what remedial steps can be taken in case of low quality indicated tensile data are not available to foundry engineers. Quality indices in the literature were developed as a measure to quantify quality to assist foundry engineers in their pursuit of higher quality. A brief review of those quality indices developed previously is provided. The quality indices can be grouped into two: (1) those with no physical meaning and (2) those that measure what fraction of the expected tensile performance is achieved. The quality index developed by the authors is based simply on the ratio of measured elongation to maximum achievable elongation, portrayed as a percentage of what is achievable. This quality index is recommended over the others. In principle the approach is applicable to all alloys. Step-by-step guidelines on its use and interpretation are provided.