Citation: Li, H.; Liang, X.; Li, Y.;
Lin, F. Performance of
High-Layer-Thickness Ti6Al4V
Fabricated by Electron Beam Powder
Bed Fusion under Different
Accelerating Voltage Values.
Materials 2022, 15, 1878.
https://doi.org/10.3390/
ma15051878
Academic Editor: Amir Mostafaei
Received: 25 January 2022
Accepted: 25 February 2022
Published: 3 March 2022
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Article
Performance of High-Layer-Thickness Ti6Al4V Fabricated by
Electron Beam Powder Bed Fusion under Different Accelerating
Voltage Values
Hongxin Li
1,2,3
, Xiaoyu Liang
1,2,3
, Yang Li
1,2,3
and Feng Lin
1,2,3,
*
1
Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China; lhx12kf@163.com (H.L.);
xiaoyu_liang@tsinghua.edu.cn (X.L.); liyangthu8@163.com (Y.L.)
2
Key Laboratory for Advanced Materials Processing Technology, Ministry of Education of China,
Beijing 100084, China
3
Bio-Manufacturing and Rapid Forming Technology Key Laboratory of Beijing, Tsinghua University,
Beijing 100084, China
* Correspondence: linfeng@mail.tsinghua.edu.cn; Tel.: +86-10-6278-8675
Abstract:
The electron beam powder bed fusion (EB-PBF) process is typically carried out using a
layer thickness between 50 and 100 µm with the accelerating voltage of 60 kV for the electron beam.
This configuration ensures forming accuracy but limits building efficiency. The augmentation of the
accelerating voltage enlarges the molten pool due to the rise in penetrability, suggesting that a higher
layer thickness can be used. Therefore, the effects of layer thickness and accelerating voltage were
investigated simultaneously in this study to explore the feasibility of efficiency improvement. Ti6Al4V
was fabricated by EB-PBF using layer thicknesses of 200 and 300
µ
m. Two accelerating voltage values
of 60 and 90 kV were used to study their effects under expanded layer thickness. The results reveal
that dense parts with the ultimate tensile strength higher than 950 MPa and elongation higher than
9.5% could be fabricated even if the layer thickness reached 300
µ
m, resulting in a building rate of up
to 30 mm
3
/s. The expansion of the layer thickness could decrease the minimum bulk energy density
needed to fabricate dense parts and increase the
α
platelet thickness, which improved the energy
efficiency. However, expanding layer thickness had a significant negative effect on surface roughness,
but it could be improved by applying augmented accelerating voltage.
Keywords:
electron beam powder bed fusion; accelerating voltage; Ti6Al4V; high layer thickness;
properties
1. Introduction
Electron beam powder bed fusion (EB-PBF) is a kind of additive manufacturing
technology which uses electron beams to selectively melt the powder layer by layer based on
three-dimensional (3D) digital models and form 3D parts [
1
,
2
]. Compared with subtractive
manufacturing technologies, parts with low thermal stress and arbitrary complex structures
can be fabricated by EB-PBF due to the high powder-bed temperature and support effect
provided by the sintered powder bed during the manufacturing process. The recycling of
the sintered powder greatly increases the material utilization rate. In recent years, metal
parts with high mechanical properties have been successfully fabricated by EB-PBF using
different materials [
3
–
9
], which demonstrates promising prospects in aerospace, medicine
and other fields.
As a powder bed fusion process, layer thickness plays a key role in EB-PBF. Generally,
the typical layer thickness for the EB-PBF process varies between 50 and 100
µ
m [
10
,
11
].
This is larger than the typical layer thickness between 20 and 50
µ
m used in laser powder
bed fusion (L-PBF) which uses a laser as the heat source to melt the metal powder. A smaller
layer thickness results in higher dimensional accuracy and surface roughness, but a lower
Materials 2022, 15, 1878. https://doi.org/10.3390/ma15051878 https://www.mdpi.com/journal/materials
