Abstract
Three dimensional porosity analysis was conducted using computed tomography for Al-Si alloy castings. Statistical analysis was performed to compare the porosities of the castings at high and low cooling rates. It was observed that the cooling rates strongly affect the formation of pores for both small and large pores. The incidence of small pores measuring 0.00003 mm(3) to 0.0004 mm(3) can be up to six times higher in castings formed at low cooling rates. For large pores measuring 300 mu m to 360 mu m, it was observed that lower cooling rates give rise to larger pores, which are known to be detrimental to castings as potential failure initiation sites.