Strategy Development for the Manufacturing of Multilayered Structures of Variable Thickness of Ni-Based Alloy 718 by Powder-Fed Directed Energy Deposition

Abstract

In this study, a manufacturing strategy, and guidelines for inclined and multilayered structures of variable thickness are presented, which are based on the results of an own-developed geometrical model that obtains both the coating thickness and dilution. This model is developed for the powder-fed directed energy deposition process (DED) and it only uses the DED single-track cladding characteristics (height, width, area, and dilution depth), the overlap percentage, and the laser head tilting-angle as inputs. As outputs, it calculates both the cladding geometry and the dilution area of the coating. This model for the Ni-based alloy 718 was improved, based on previous studies of the single clad working both vertically and at an inclined angle, adding the equations of the single clad characteristics with respect to the main process parameters. The strategy proposed in this paper for multilayered cladding consisted of both adding an extra clad at the edges of the layer and using a variable value of the overlap percentage between clads for geometric adaptations. With this strategy, the material deposition is more accurate than otherwise, and it shows stable growth. Manufacturing a multilayered wall of wider thicknesses at higher heights was utilized to validate the strategy.

Directed Energy Deposition of AISI 316L Stainless Steel Powder: Effect of Process Parameters

“…These values were selected based on the knowledge acquired using similar powders [24]. Furthermore, results reported in the literature suggest to use similar overlap values in order to avoid a strong increase in the layer height from the first scan track to the last one of the layer [25]. Based on the scan geometries, the displacement values (dX and dZ) for each cube were then calculated according to Equations (3) and (4).…”

Semi-Hybrid CO2 Laser Metal Deposition Method with Inter Substrate Buffer Zone

“…For the semi-hybrid method ( Figure 2 b), four separate regions were identified: IV—fusion line of powder layer and substrate, V—fusion zone between the buffer layers and wire deposited layers, VI—zone of wire penetrated buffer layers, VII—pure wire deposited zone. For the powder deposition method, two separate regions were identified: IV—fusion line of powder layer and substrate (similar for the region IV in S-HDM), VIII—pure powder deposited zone [ 20 ]. Moreover, the fusion mechanisms in the deposition process are different for all considered methods, i.e., for the first method, deep penetration in the substrate occurs, while for the second method, deep penetration occurs only inside the buffer layer and does not reach the substrate material, and for the third method, fusion mechanism appears alongside the substrate surface [ 21 ].…”

Effect of Heat Treatment on the Microstructure and Hardness of Ni-Based Alloy 718 in a Variable Thickness Geometry Deposited by Powder Fed Directed Energy Deposition

“…The dimensions of the target structure were a 50 mm in length wall with a dove tail cross section that starts on the substrate with a width of 7 mm increasing in both edges at 65° wall angle (θ) until reach a total height of 15.6 mm (Figure 2). Strategy for manufacturing a demanding geometry with a multilayer structure of variable thickness as a dove tail geometry, is based on the strategy developed in previous works for multilayered structures of variable thickness [27][28][29], where complex geometries were deposited tilting the nozzle on a horizontal substrate.…”

“…In order to obtain the tool path according to these requirements, the trajectory was programed employing Python software. Strategy for manufacturing a demanding geometry with a multilayer structure of variable thickness as a dove tail geometry, is based on the strategy developed in previous works for multilayered structures of variable thickness [27][28][29], where complex geometries were deposited tilting the nozzle on a horizontal substrate.…”

“…In order to obtain the tool path according to these requirements, the trajectory was programed employing Python software. Optimum working conditions obtained from previous works [27] were selected for alloy 718 deposition through the 4-stream nozzle. All other processing variables were held constant considering previous experience.…”