Characterization and Optimization of Process Parameters for Directed Energy Deposition Powder-Fed Laser System

Abstract

Laser-directed energy deposition (L-DED) is a type of additive manufacturing (AM) technology that allows the manufacture of complex geometry components in a layer-by-layer way and can be considered an emerging manufacturing technique. The process efficiency and properties of produced parts are closely linked to its parameters, i.e., laser power, deposition speed, material flow rate and, inert gas flows. These operational parameters usually are different depending on the machine and material employed. The best combination of process parameters is fundamental to obtain the best characteristics together with process sustainability for each manufactured component. At the present work, an L-DED head and a powder feeding system are combined in a particular machine to deposit Inconel 625 on a substrate made of AISI 304 stainless steel. A combination of analytical studies, CFD simulations, and experimental tests was carried out, finding a process setting that offers a higher concentration of particles, quality depositions, and optimal cooling rates, reducing gas and material consumption during the process. After some in-situ tests, the best results were employed to fabricate thin wall structures and solid components. The specimens were characterized by laser confocal microscopy, roughness, and Vickers microhardness measurements, finding exciting results with a significant reduction in gas consumption and metal powder usage.