Article
Laser Powder Bed Fusion (LPBF) of In718 and the Impact of
Pre-Heating at 500 and 1000
◦
C: Operando Study
Asif Ur Rehman
1,2,3,
* , Fatih Pitir
1
and Metin Uymaz Salamci
2,3,4
Citation: Ur Rehman, A.; Pitir, F.;
Salamci, M.U. Laser Powder Bed
Fusion (LPBF) of In718 and the
Impact of Pre-Heating at 500 and
1000
◦
C: Operando Study. Materials
2021, 14, 6683. https://doi.org/
10.3390/ma14216683
Academic Editors: Ludwig Cardon
and Clemens Holzer
Received: 4 October 2021
Accepted: 1 November 2021
Published: 5 November 2021
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Attribution (CC BY) license (https://
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4.0/).
1
ERMAKSAN, Bursa 16065, Turkey; fatih.pitir@ermaksan.com.tr
2
Department of Mechanical Engineering, Gazi University, Ankara 06570, Turkey; msalamci@gazi.edu.tr
3
Additive Manufacturing Technologies Application and Research Center—EKTAM, Gazi University,
Ankara 06560, Turkey
4
Manufacturing Technologies Center of Excellence—URTEMM A.S., Ankara 06980, Turkey
* Correspondence: asyf.rehman@gmail.com; Tel.: +90-53-9387-8001; Fax: +90-22-4294-7549
Abstract:
The morphology of a melt pool has a critical role in laser powder bed fusion (LPBF).
Nevertheless, directly characterizing the melt pool during LPBF is incredibly hard. Here, we present
the melt pool flow of the entire melt pool in 3D using mesoscopic simulation models. The physical
processes occurring within the melt pool are pinpointed. The flow patterns throughout the same are
exposed and measured. Moreover, the impact of pre-heating at 500 and 1000
◦
C has been described.
The study findings offer insights into LPBF. The findings presented here are critical for comprehending
the LPBF and directing the establishment of improved metrics for process parameters optimization.
Keywords:
multiphysics; laser powder bed fusion; LPBF; temperature dependent properties; pre-
heating; superalloy; In718
1. Introduction
Additive manufacturing (AM) provides customized designs, reduced preparation
time, and the ability to create complicated shapes. Many advanced technological applica-
tions [
1
] such as aerospace [
2
], biomedicine [
3
,
4
] and architecture [
5
,
6
] have considerable
interest in it. Laser powder bed fusion (LPBF) is one of the most widely used additive man-
ufacturing (AM) technologies because of its many advantages, which include significantly
reduced structural limitations, high reproducibility, and on-time delivery [
7
]. In the LPBF,
the metal particles are deposited layer upon layer via the blade or roller, followed by the
fusing of particles by laser on particular locations to generate the desired slices, which is
driven by CAD data [
8
]. There are a variety of flaws that are detrimental to efficiency and
component quality [
9
–
11
] including balling, fractures, pores, and poor layer uniformity. As
a result, it is necessary to better understand the deformations and the influence of input
factors on the melt pool [12,13].
It has been shown that a variety of factors, including scan speed, laser power, particle
sizes distribution (PSD), and layer height [
14
], have an impact on the melt pool and, there-
fore, the quality of the elements created [
15
,
16
]. Systematic attempts have been undertaken
to explain the intricate melt pool dynamics [
12
,
17
–
20
], process parameters, and recurring
defects in terms of the processing parameters that have an influence on the process. Studies
by Hodge et al. and Lin et al. [
21
,
22
] looked at the effect of laser power and scan speed
on the surface properties of LPBF parts. According to the research [
21
–
23
], irregularities,
deformations, cracking, and other deficiencies on the surfaces are produced at a high scan
rate, resulting in more surface defects. Studies have focused on the formation of the defect
during the LPBF techniques of metallic metal powder [
24
]. The results of the investigation
revealed that the energy density (ED) had a substantial influence on the formation of de-
fects. The physics underpinning the dynamic interaction between the process parameters
Materials 2021, 14, 6683. https://doi.org/10.3390/ma14216683 https://www.mdpi.com/journal/materials
