A Systematic Evaluation Method for Grain Morphology in MPF–LB Simulations of Semi-solid Deformation

Semi-solid deformation strongly influences the formation of casting defects, and understanding its governing factors is essential for improving the quality of cast products. In this study, we develop a method to systematically evaluate the influence of grain morphology on semi-solid deformation behavior using multi-phase-field lattice Boltzmann simulations. Cross-shaped grain morphologies are artificially generated, and two approaches—compression and growth—are introduced to create semi-solid mixtures with a wide range of solid fractions. Semi-solid simple shear deformation simulations reveal that deformation proceeds through grain–grain sliding and rearrangement when grain circularity is high, whereas grain clusters form and their rotation govern deformation when circularity is low. Furthermore, lower circularity leads to the formation of larger clusters that are less likely to rotate. These findings demonstrate that grain morphology is a key factor strongly affecting semi-solid deformation behavior. In addition, the proposed methodology is shown to be effective for systematically evaluating semi-solid deformation with respect to both grain morphology and solid fraction.