Microstructural and micromechanical characterization of IN718 theta shaped specimens built with electron beam melting

• DOI: 10.1016/j.actamat.2016.02.005
• Publication Date: 2016-02-23T23:03:27Z
• Authors: Ercan Cakmak; Michael M. Kirka; Thomas R. Watkins; Ryan C. Cooper; Ke An; Hahn Choo; Wei Wu; Ryan R. Dehoff; Sudarsanam S. Babu
• Keywords: Characterization; Lattice (music); Inconel

Abstract Theta-shaped specimens were additively manufactured out of Inconel 718 powders using an electron beam melting technique, as a model complex load bearing structure. Two different build strategies were employed; producing two sets of specimens. Microstructural and micro-mechanical characterizations were performed using electron back-scatter, synchrotron x-ray and in-situ neutron diffraction techniques. In particular, the cross-members of the specimens were the focus of the synchrotron x-ray and in-situ neutron diffraction measurements. The build strategies employed resulted in the formation of distinct microstructures and crystallographic textures, signifying the importance of build-parameter manipulation for microstructural optimization. Large strain anisotropy of the different lattice planes was observed during in-situ loading. Texture was concluded to have a distinct effect upon both the axial and transverse strain responses of the cross-members. In particular, the (200), (220) and (420) transverse lattice strains all showed unexpected overlapping trends in both builds. This was related to the strong {200} textures along the build/loading direction, providing agreement between the experimental and calculated results.