Revealing the tensile anisotropic mechanisms of additive manufactured IN718 alloy based on crystal plasticity modeling

Abstract

The mechanical behavior of IN718 alloy produced by additive manufacturing (AM) displays significant anisotropy due to its unique microstructure, which differs markedly from conventionally manufactured materials. This study focuses on understanding the tensile anisotropy of AM IN718 alloy by employing a crystal plasticity approach. Grain boundary strengthening is modeled through the Hall-Petch relationship, and a modified dislocation mean free path model is incorporated to account for the grain size effect. These models are applied to simulate the influence of grain morphology (columnar and equiaxed grains) and crystallographic texture on the tensile response of AM IN718 alloy. The results reveal that columnar grains and texture affect both yield strength and strain-hardening behavior. Columnar grains, aligned along the build direction, induce significant variations in yield strength and strain-hardening due to differences in effective grain size in different loading directions. Texture can also affect the strain-hardening behavior by influencing the dislocation multiplication. The study offers a qualitative assessment of how grain morphology and crystallographic orientation govern the anisotropic behavior of AM IN718 alloy, providing insights that can guide the optimization of mechanical properties in AM-produced components.