Micromechanical modeling of fracture in high-pressure die cast aluminum

Abstract

High-pressure die cast aluminum is being incorporated into the production of electric vehicles in order to increase vehicle efficiency and reduce manufacturing costs. The process is known as Mega Casting and can produce large scale components with complex geometry in one process, drastically reducing the amount of welds and joints. Due to the process, the aluminum components possess a complex microstructure with different phases and porosity, which makes the mechanical properties difficult to predict. Today, there is a lack of Finite Element (FE) and material models that can capture these microstructural defects on a component scale. Throughout the project, a method for generation of three-phase microstructure models based on Computer Tomography (CT) scanning and Scanning Electron Microscope (SEM) images is developed. Numerical studies on mesh design, time integration and boundary conditions are performed with the intention to optimize computational costs while maintaining accuracy. Furthermore, the variation in mechanical properties depending on morphology is studied by simulating a range of different microstructures subjected to different load cases. The results show that it is possible to generate three-phase microstructures that represent the eutectic silicon region in HPDC-aluminum components. The choices of the numerical model and modeling have impact on computational efficiency and accuracy. Furthermore, it is possible to vary the internal morphology in the model in order to obtain mechanical response data for a wide range of microstructures.