Laser-assisted directed energy deposition of nickel super alloys: A review

Abstract

Laser additive manufacturing using directed energy deposition (LAM-DED) is an advanced manufacturing process widely deployed for fabricating near net-shaped engineering components. LAM-DED has been successfully used for processing wide variety of pure metals and their alloys. The list of these metals and alloys is appending rapidly. Among the various materials successfully deployed for LAM-DED, nickel super alloys are extensively used for various engineering applications due to the unique combination of superior properties, such as high temperature strength, oxidation, corrosion resistance, etc. Recent studies show that LAM-DED built nickel super alloys finds wide applications in aerospace and automotive sector for fabricating engineering components, repairing, remanufacturing, and cladding. Considering the importance of LAM-DED and nickel super alloys, significant amount of work is already reported. This paper presents a comprehensive review on LAM-DED of nickel super alloys. It introduces LAM technology and nickel super alloys with a compilation of various lasers and processing parameters deployed for LAM-DED of nickel super alloys. The paper compiles the metallurgy, mechanical properties, processing issues, and effect of post-processing on LAM-DED built nickel super alloys. This paper will serve as a quick-start for novices to understand LAM-DED of nickel super alloys and will be useful as a reference document for researchers and industrialists in the field.

Directed Energy Deposition (DED) Process: State of the Art

“…The DED process utilizes the concept of cladding and welding processes [1-4, Fig. 1 Powder feeding methodologies of LAM-DED processes (Redrawn and modified figures of reference 57) [57]: (a) coaxial feeding and (b) off-axis feeding 6,8,24,32,[42][43][44][45][46][47][48][49][50][51][56][57][58][59][60]. Thermal energy, such as a laser, electron beam, welding heat flux, etc., is focused on the previous layer, as shown in Table 1 [1-4, 6, 8, 24, 32, 42-51, 56-62].…”

“…The DED process consisting of a powder feeding device and a laser is known as a laser additive manufacturing (LAM)-DED process [60]. The wire feeding type DED processes are classified into wire and arc additive manufacturing (WAAM), wire and laser additive manufacturing (WLAM), and wire and electron beam additive manufacturing (WEAM) processes according to used thermal energies [1,4,6,24,46,[58][59][60][61][62][63][64][65][66][67]. The DED process with off-axial feeding devices of the feedstock relative to the focused thermal energy is sensitive to feed orientations and deposition conditions [59].…”

“…Energy densities of the laser, the arc and the electron beam for the DED processes are on the order of 10 6 , 10 4 and 10 8 W/ mm 2 , respectively, as shown in Table 2 [46]. The LAM-DED, WAAM and WLAM processes use a shield gas to prevent oxidation of the molten pool during the deposition [6,24,34,40,42,44,[56][57][58][59][60][64][65][66][67][68]. The WEAM processes are operated in a vacuum furnace unlike the LAM-DED, WAAM and WLAM processes [4,46,62,63,[69][70][71][72].…”

Parametric investigation and characterization on SS316 built by laser-assisted directed energy deposition

“…Figure 1 presents the typical schematic of an L-DED system. L-DED is successfully used for processing a wide variety of materials like Fe-based alloys, 9,10 Ni-based alloys, 4,11 Co-based alloys, 12,13 etc. for various engineering applications.…”

“…3 This results in finer microstructure and better mechanical strength than as-cast samples. 4 LAM can be primarily classified as follows: laser-assisted powder bed fusion (L-PBF) 5,6 and laser-assisted directed energy deposition (L-DED). 7,8 The basic difference lies in the methodology deployed for material feeding.…”