Influence of Grain Size and Shape of Mechanical Properties of Metal AM Materials

Abstract

Metal powder-based additive manufacturing (PAM) typically results in microstructures with a texture and columnar grain structure. The columnar grains can vary greatly in size and shape throughout the microstructure, which can significantly affect the mechanical properties of the resulting part. A previous study developed a microstructurally informed crystal plasticity constitutive model that took into account grain sizes and shapes then showed that grain geometry can influence the prediction of mechanical behavior of the part. In the present work, the influence of grain aspect ratio, size, and loading direction on the resulting mechanical properties of the PAM part are investigated through a parametric study. Results show that considering size and shape effects have the tendency to increase the material yield strength while decreasing the initial strain hardening modulus. Using this knowledge, it may be possible to optimize a PAM microstructure using process parameters to produce a part which exhibit superior yield strength and hardening modulii compared to traditional materials.