Crystal plasticity finite element study of tension-induced anisotropic contraction of additively manufactured Haynes 282

Cylindrical Haynes 282 tensile specimens fabricated by laser powder bed fusion (L-PBF Haynes 282) have shown anomalous tensile deformation behavior, characterized by anisotropic lateral contraction and elliptical tensile fracture surfaces. In this work, crystal plasticity finite element simulations are conducted to explore the underlying mechanisms of such anomaly. Cylindrical models of grain aggregates are created according to the experimentally observed grain structure of L-PBF Haynes 282. The initial crystallographic orientations are assigned to generate a range of textures ranging from single crystalline to completely random. The evolution of the shapes and crystallographic textures of the simulated grain aggregates during tensile deformation have been analyzed and compared with experiments. It is found that the near-single crystal texture of L-PBF Haynes 282 is responsible for the deformation anomaly. Specifically, the simulated single crystal under tension along the [110] axis exhibits strong anisotropic lateral contraction; and the deformation of the model with random texture is symmetric about the loading axis. While both models evolve a relatively strong [111] pole along the loading axis during deformation, the orientation of the single crystal model splits about the [11 over bar 0\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$1\overline{1 }0$$\end{document}] direction and the random-texture model evolves into a strong fiber texture. When small, random misorientations are introduced into the single crystal model, the deformation anisotropy and texture evolution appear to be the intermediate of the two extreme cases; and resemble what is observed from the experiment.