Page 97 - MSAM-2-3

Materials Science in Additive Manufacturing Validation of a novel ML model for AM-PSP

Table 2. Process specific attributes of PBF and DED metal AM techniques
Process Materials Comments References
Powder bed
fusion
EB-PBF Titanium alloys (Ti-6Al-4V), nickel alloys (Inconel (i) Vacuum operation condition, which reduces thermal [17–26]
625, 718, 740, Rene 142), steel alloys (SS 316), TiAl convection, thermal gradients, contamination, and
(γ-TiAl), high-entropy alloy (AlCoCrFeNi) oxidation
(ii) High build but inferior dimensional and surface finish
(iii) High build chamber temperature and preheating reduce
the thermal gradient in the powder bed
(iv) Preheating holds the powder together and acts as a
support structure for the overhang structure
L-PBF Titanium alloys (Ti-6Al-4V), nickel alloys (Inconel (i) Protective gas operation environment (argon, nitrogen) [27–34]
625, 718, 738, 939), steel alloys (316 SS, 420 SS, 4340, (ii) Low build rate but high accuracy, larger build-up
M2 HSS, 17-4 SS), aluminum alloys (AlSi10Mg, volumes compared with EB-PBF
AlSi12, Al-Sc), high-entropy alloys (FeCoCrNi) (iii) A fast cooling rate and a large thermal gradient leads to
large residual stress
(iv) Stress relief heat treatment and/or hot isotropic pressing
(HIP) needed to achieve final mechanical properties
Directed energy
deposition
EB-PBF (wire) Steel alloys (347 SS), titanium alloys (Ti-6Al-4V), (i) Fabricate functionally graded and pure metal [35,36]
aluminum alloys (2219 Al) components
Laser (wire) Titanium alloys (Ti-6Al-4V), nickel alloys (ii) Capability to repairing and cladding parts [37–39]
and LENS (Inconel 718), steel alloys (4340) (iii) The high deposition rate and large volumes
(iv) Limited by geometrical freedom due to lack of support
WAAM Titanium alloys (Ti-6Al-4V), steel alloys (v) Inadequate geometrical accuracy and extremely pool [40,41]
(10V, 15-5 PH, 309), aluminum alloys (Al-Mg) surface finish.
Abbreviations: EB-PBF: Electron beam powder bed fusion; LENS: Laser engineer net shape; L-PBF: Laser powder bed fusion; WAAM: Wire arc
additive manufacturing.
studies have summarized different ML methods and their Since AM technologies afford the creation of complex
applications in AM manufacturing [58-60] . geometries, shorten fabrication time and material cost, and
enable low-volume production and mass customization,
To achieve the designed geometric dimensioning and
tolerancing (GD&T) and surface finish, post-processing, they offer a new approach to fabricating Ti-6Al-4V
alloys . However, in most mechanical and aerospace
[62]
usually a subtractive machining process, is required Ti-6Al-4V applications, post-processing, such as stress
for metal AM components. In a production cycle from relief heat treatment and computer numerical control
design to manufacturing to inspection, GD&T is the (CNC) machining, are required to achieve the required
common language to communicate the acceptable quality mechanical properties, designed tolerance, and surface
of geometric elements of the parts. GD&T standard is finish. Summarizing the prior work in the machining of
based on mathematical representations of an acceptable AM Ti-6Al-4V, researchers found that when compared
range of variation in geometry based on manufacturing to conventionally manufactured Ti-6Al-4V products, the
process-specific knowledge bases to specify design Ti-6Al-4V alloys fabricated using AM processes have highly
intent and prevent misrepresentation during production different material characteristics such as microstructure,
processes. The tolerance specification is the specification and different mechanical properties such as yield strength,
of the type and value of tolerance based on the GD&T hardness, tensile strength, and elongation. In addition,
standard . Compared to traditional processes, AM researchers have established that machining behavior, such
[61]
processes can produce complex geometries, which lead to as cutting force in turning and milling, finished surface
potential tolerance and specification issues. In addition, roughness, and tool wear behavior, is quite different when
since metal AM processes produce components with machining AM Ti-6Al-4V parts compared with conventional
different microstructure and mechanical properties when wrought parts. However, a critical knowledge gap exists in
compared to traditionally manufactured parts, there is a understanding the fundamental relationship between AM
critical research potential to discover ideal post-process Ti-6Al-4V material properties and their machining behavior,
machining parameters for AM products. specifically across different AM processing techniques.

Volume 2 Issue 3 (2023) 5 https://doi.org/10.36922/msam.0999