Luke N. Brewer

Abstract: Here we introduce a novel thermo-mechanical Solid State Additive Manufacturing (SSAM) process referred to as Additive Friction Stir (AFS) manufacturing that provides a new and alternative path to fusion-based additive manufacturing processes for developing fully-dense, near-net shape components with a refined-equiaxed grain morphology. This study is the first to investigate the beneficial grain refinement and densification produced by AFS in IN625 that results in advantageous mechanical properties (YS, UTS, ef) at both quasi-static and high strain rate. Electron Backscatter Diffraction (EBSD) observed grain refinement during the layer deposition in the AFS specimens, where the results identified fine equiaxed grain structures with even finer grain structures forming at the layer interfaces. The EBSD quantified grains as fine as 0.27 µm in these interface regions while the average grain size was approximately 1 µm. Additionally, this is the first study to report on the strain rate dependence of AFS IN625 through quasi-static (QS) (0.001/s) and high strain rate (HR) (1500/s) tensile experiments using a servo hydraulic frame and a direct tension-Kolsky bar, respectively, which captured both yield and ultimate tensile strengths increasing as strain rate increased. The HS results exhibited an approximately 200 MPa increase in engineering strength over the QS results, with the fracture surfaces at both strain rates aligned with the maximum shear plane and exhibiting localized microvoids.

TL;DR: In this article, a method for the visualization of plastic deformation in electron back-scattered diffraction (EBSD) data has been developed and is described in this article, based on mapping the intragrain misorientation in polycrystalline metals.

TL;DR: A method for the visualization of plastic deformation in electron back-scattered diffraction (EBSD) data has been developed and is described in this article based on mapping the intragrain misorientation in polycrystalline metals.

TL;DR: In this paper, the first description of the process parameter relationship to the microstructure/nanostructure and mechanical properties of Aluminum Alloy 6061 AFS-D deposits was provided.