Over the past years, wire-based direct energy deposition (DED) has been transitioning from rapid
prototyping to the production of end-use part and mass production. However, a wide market
penetration of the DED has not happened yet. The difficulties for wide-scale market adoption to
critical structural components are related to the development cost for process optimization and for
manufacturing of high-quality parts. For metallic components, the process conditions (e.g., power,
speed, tool path) control the material and mechanical properties/performance of the printed part. The
thermal history strongly determines the phase fraction, morphology, growth pattern, size of
microstructure, and nature of defects. Thus, in this study, we: 1) developed a thermal simulation using
finite element method, 2) experimentally measured thermal histories from a U-shaped part with four
tool paths of horizontal, vertical, raster, and contour to calibrate and validate the thermal model, and 3)
investigated the effect of thermal history on microstructure evolution and quantified the
microstructural variation during the printing process.Mechanical Engineerin
