Evolution of microstructure and mechanical property enhancement in wire-arc directed energy deposition with interlayer machining

Wire-Arc Directed Energy Deposition (Wire-Arc DED) has emerged as a promising additive manufacturing technique known for its high deposition rates. However, the variability in microstructure and mechanical properties (e.g., hardness) of the manufactured components poses significant challenges. This study delves into these issues, focusing on the influence of interlayer machining on the microstructural evolution and mechanical properties of thin-wall Wire-Arc DED structures. It is shown that as-built Wire-Arc DED structures exhibit a pronounced microstructure variation between different regions along the build direction, primarily governed by the differences in thermal history. In contrast, a Hybrid Wire-Arc DED process that integrates interlayer machining into the build process to induce severe plastic deformation leads to a microstructure characterized by refinement and homogenization, compared to a Wire-Arc DED process. This study provides insights into the impacts of plastic deformation due to machining and thermal cycling due to subsequent layer depositions on the microstructure and hardness obtained in Wire-Arc DED and Hybrid Wire-Arc DED processes, highlighting the potential of hybrid manufacturing to generate tailored microstructures to enhance the mechanical performance of functional components.