A Process Optimization Framework for Direct Energy Deposition: Densification, Microstructure, and Mechanical Properties of an Iron-Chromium Alloy

Abstract

Direct Energy Deposition (DED) is a metal additive manufacturing (AM) technique with the ability to fabricate compositional gradients through in-situ alloying. To fabricate functional gradients, it is necessary to understand what process parameters are suitable for printing the materials in the gradient. This study proposes a framework to optimize several critical process parameters: laser power, scan speed, mass flow rate, hatch spacing, and layer height. The framework utilizes single laser scans and geometric criteria to propose a range of process parameters likely to result in high-density parts. The proposed framework is validated by printing Fe-9wt.%Cr as a surrogate for radiation damage-resistant steels. These steels are of interest for functionally graded plasma-facing components in fusion reactors. Using the framework, high-density Fe-9wt.%Cr samples were fabricated using a variety of process parameters. The mechanical properties and microstructure of as-printed Fe-9wt.%Cr are characterized using tensile testing, microscopy, and X-ray diffraction.