Optimization of Direct Energy Deposition of 304L Stainless Steel through Laser Process Parameters

Abstract

The quality of metal components manufactured by laser-based additive manufacturing technologies is governed by the process parameters. Moreover, the process parameters differ depending on the material used. In particular, direct energy deposition (DED) technology is vulnerable to the control of external environmental variables, and there are many process variables, such as powder characteristics and laser parameters, and thus many tests are required to determine the optimal parameters. In this study, an experiment was conducted to derive the conformity criterion of the DED process for metal powder (STS304L). First, the effects of laser energy output, laser header moving speed, powder feed rate, and gas feed rate on the DED process were studied. The experimental results showed that the deposition height decreased as the laser header moved faster and that the dilution ratio and the width of the heat-affected zone depended on the laser power and powder feed rate. Specimens were printed based on the process parameter values determined in the experiment, and tensile tests were conducted to analyze their mechanical performance.

Direct Energy Depositions of a 17-4 PH Stainless Steel: Geometrical and Microstructural Characterizations

“…where Ac (mm 2 ) is the area across the clad, and Am (mm 2 ) is the area across the molten diluted part. According to some experimental findings, dilution is strongly dependent on the process parameters [3,[20][21][22][23], and by several authors, values in the range of 10%-30% were considered appropriate to guarantee adequate bonding and adhesion with the substrate [20,23,24]. In addition to the geometrical features, the soundness of the deposited materials in terms of porosity and defects, such as detachment between the clad and the substrate, was also evaluated.…”

“…According to these preliminary results, the highperformance four sets of parameters were selected with respect to all the following criteria: dilution in the range of 10%-30%, the height of the clad less than 400 µ m, and a weighted sum of defects less than 3.5 (ranking from 0.5 to 2 as concerns the porosity, and 4 if a detachment is observed). According to some experimental findings, dilution is strongly dependent on the process parameters [3,[20][21][22][23], and by several authors, values in the range of 10%-30% were considered appropriate to guarantee adequate bonding and adhesion with the substrate [20,23,24]. In addition to the geometrical features, the soundness of the deposited materials in terms of porosity and defects, such as detachment between the clad and the substrate, was also evaluated.…”