| The purpose of this study was to conduct experiments to determine the relevant microstructural features that influence mechanical properties of the high-pressure die-cast magnesium alloy AM60B. From these resulting experimental data, predictive capabilities of these relationships were developed. This work continues from a previous M.E.Sc. thesis [1].;Medium- (∼8mum) and high-resolution (∼1mum) X-ray tomography testing were completed on several samples of AM60B, and one sample at several levels of loading during uniaxial tension, prior to fracture. The fracture location, strain and stress of the sample during uniaxial tensile testing were predicted using a critical strain model, previously presented in [1], and a new, modified failure model. FE simulations were used to simulate the fracture of uniaxial tensile samples with porosity. It was determined that the critical features leading to fracture of AM6OB samples are the area fraction of porosity, and the proximity of the centre of mass of the porosity to a free surface. With these two features, a mathematical model was formulated capable of predicting the fracture strain of six AM6OB samples tested in uniaxial tension within an error percentage of 6.8%.;Multi-axial testing was completed on several samples of AM60B. Uniaxial compression, plane-strain compression, and shear testing were completed to fracture. FE simulations were found to accurately predict the deformation and true stress-true strain curves each of these loading states. An accurate yield surface was then established for the deformation of AM6OB in plane-stress up to 10% true effective strain. FE simulations were completed under plane-strain tension, balanced bi-axial tension, shear testing, and uniaxial tensile testing to determine a fracture surface for different area fractions of porosity for plane-stress loading. These fracture surfaces were validated using results from uniaxial tensile testing.;Keywords: Finite element analysis simulations, high-resolution X-ray tomography, X-ray diffraction techniques, magnesium die-castings, failure modelling, multi-axial material testing, structure-property relationships.;Metallographic and indentation techniques were used to determine the skin thickness in regions of different solidification conditions throughout the die-casting. It was determined that the yield strength of AM6OB samples tested in uniaxial tension is described by a modified Hall-Petch relationship. These results were then used in FE (finite element) simulations to establish the predicted yield strength for uniaxial tensile samples given the average grain size. |
