Optimization of a step casting die geometry to evaluate the potential mechanical performance of AM60B magnesium alloys

Non-destructive testing has been carried out on AM60B magnesium alloy castings obtained by using two different permanent moulds. The results highlighted a very different defects content. In this paper, the benefits of adopting an optimised die to better evaluate the final castings’ properties are analysed. Numerical simulations have been performed to study the filling and the solidification behaviour of the alloy by changing the die cavity geometry, in order to minimise the presence of defects. The redesigned runner system prevented inclusions to enter the die cavity and allowed a laminar flow of the metal through the gate. Further, defects formation has been investigated using criteria functions provided by the simulation software, and the results confirmed the reliability of the die design. Comparing the simulation and experimental results, it's possible to verify a good correspondence, so allowing to establish semi-empirical rules to forecast the final properties of Mg alloys castings.