Experimental and numerical investigations of oxide-related defects in Al alloy gravity die castings

This research aimed to study the formation and distribution of oxide-related defects in the gravity die casting process of an AlSi7Cu0.5Mg alloy by using experimental and numerical investigations. Metallographic and image analysis techniques were conducted to map the distribution of oxide inclusions inside the casting at the microscopic level. Numerical simulations were used to analyse the filling and solidification stages, and to foresee the turbulence of the melt and the formation of the oxide defects. The results show that most of the defects were correlated with the oxide layers or bubbles entrained inside the liquid metal. The accuracy of the numerical code in simulating the metal fluid-dynamic behaviour and the heat transfer was verified, and the results were in agreement with the experimental findings. The numerical distribution of defects was consistent with the experimental results, proving that the model successfully predicted the formation of oxide-related defects.