The Effect of Hidden Damage on Local Process Variability in Al-10 Pct Si Alloy High-Pressure Die Castings

Abstract An approach to evaluate and quantify process variability in the mechanical performance of castings is explored. The process variability describes the effect of hidden damage given to the metal before solidification on the material performance measured by elongation to failure. The approach is demonstrated on a casting produced by high-pressure die casting (HPDC) with different filling conditions in serial production. Statistical analyses have been conducted on data obtained from several positions throughout the casting to determine whether a position is performing differently from other positions. The results show that elongation in most positions follows the same Weibull distribution. However, the local evaluation shows that one position stands out and follows a separate distribution. Casting simulations, Digital Image Correlation (DIC), and Scanning Electron Microscopy (SEM) reveal that this position displays an increased amount of hidden damage that causes the local reduction in elongation. The investigated changes in prefill amount do not significantly affect the material quality, which is more controlled by the quality of the melt and the nature of mold filling.