Influence of Mould System Design on the Properties of Hybrid-Cast Samples Using Low-Pressure Sand Casting

Abstract The design of mould systems is essential for ensuring the feasibility and quality of hybrid-cast parts produced via low-pressure sand casting. This study systematically investigated several different mould system designs with varying preheating parameters to determine their influence on the mechanical properties and microstructure of the bonding interface. To ensure proper material bonding between the steel sheets and the Al-cast parts, an AlSi-PVD coating was applied to the steel sheets. An induction coil was used to attain the necessary preheating of the steel inserts. Joining properties were quantitatively assessed using shear tensile tests, which were supplemented by SEM/EDX analyses performed on several cross-sections and fracture surfaces. Furthermore, FEM mould filling and solidification simulations were conducted and correlated with the microstructural results. It was found that higher preheating temperatures, a vertical mould filling orientation, and an inert gas atmosphere can improve bonding characteristics, shifting the failure mechanism from a brittle to a more ductile fracture behaviour. This also improved the stability of the hybrid casting process by reducing scatter in the results. Additionally, the morphology of the fracture surfaces and the cross-section analyses could be directly correlated with the melt flow and temperature distributions in the bonding area predicted by the FEM simulations. The combined results allow a comprehensive understanding of the observed change in coating morphology as well as the three identified failure mechanisms of the bonded joints.