Functionally Graded Additive Manufacturing of Thin-Walled 316L Stainless Steel-Inconel 625 by Direct Laser Metal Deposition Process: Characterization and Evaluation

Abstract

Direct Laser Metal Deposition (DLMD) is a state-of-the-art manufacturing technology used to fabricate 316L stainless steel/Inconel 625 functionally graded material (FGMs) in this research. For the practical application of these materials in the industry, the effects of process parameters on the geometric characteristics and surface roughness require more investigation. This FGM was additively manufactured in five layers by changing the 316L stainless steel/Inconel 625 ratio in each layer. The effects of laser power on geometric characteristics, height stability, and surface roughness were investigated. The microstructural analysis and microhardness profiles were studied. The results show that despite the high solidification rate, the segregation of alloying elements into dendritic areas occurred. It was also found that increasing the laser power will increase the height, width, height stability, and surface roughness of the gradient walls. The maximum width and height of the deposited layers were 1.615 and 6.42 mm, respectively, at the highest laser power (280 W). At the laser power of 220 W, the least surface roughness (Ra = 105 µm) and the best height stability (0.461 mm) will be obtained. The microhardness values will differ in various sections of the gradient walls in a range of 225–277 HV.

Untapped Opportunities in Additive Manufacturing with Metals: From New and Graded Materials to Post-Processing

“…In this regard, DED is more popular due to its powder-blowing or wire-injection mechanism and, thus, high flexibility in adjusting and altering the chemical composition during the process [66]. Figure 18 shows a laser-directed energy deposition (L-DED) process able to continuously control the chemical composition along the build direction to fabricate an FGM part [67]. In contrast, the difficulty of successively changing the composition of the powder bed in the PBF system has made it less likely to be used for the fabrication of compositionally graded materials, though PBF is leading the production of structural gradients (e.g., graded lattice).…”

Study on Optimization Strategy for the Composition Transition Gradient in SS 316L/Inconel 625 Functionally Graded Materials

“…These blades demonstrate excellent performance in high-temperature, high-stress and corrosive environments [ 8 , 9 , 10 ]. Currently, several nickel-based superalloy and stainless steel FGMs have been successfully developed, including SS 316L/Inconel 718 [ 5 , 11 , 12 ], SS 316L/Inconel 625 [ 9 , 13 ], SS 304L/Inconel 625 [ 10 ] and SS 321/Inconel 625 [ 14 ].…”