Modelling of Microstructure Evolution in Wire-Based Laser Direct Energy Deposition with Ti-6Al-4V

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