Additive Manufacturing of Titanium Alloys
JOM
Additive Manufacturing of Titanium Alloys
M. QIAN 0
D.L. BOURELL 0
0 1.-Centre for Additive Manufacturing, School of Engineering, RMIT University , Melbourne, VIC 3000 , Australia. 2.-Mechanical Engineering and Materials Science and Engineering, University of Texas , Austin, TX, USA. 3.-
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Titanium alloys are among the most extensively
studied metallic materials in the broad context of
metal additive manufacturing (AM), and the last
decade has seen increased niche applications of
additively manufactured titanium products.
Additive manufacturing of titanium alloys continues to
attract significant research attention today. Invited
by the JOM editorial office, we have organized 13
solicited papers for the December 2017 issue of JOM
under the topic ‘‘Additive Manufacturing of
Titanium Alloys’’. The key features of each accepted
contribution are summarized as follows.
In the first article titled ‘‘New Development in
Selective Laser Melting of Ti-6Al-4 V: A Wider
Processing Window for the Achievement of Fully
Lamellar a + b Microstructures’’, Lui and
co-workers investigated selective laser melting (SLM) of
Ti6Al-4 V alloy with the less commonly used layer
thickness of 90 lm, with a view to broadening the
flexibility of the SLM process. Fully lamellar a b
microstructures were produced in the as-built state
through control of the interlayer time. As a result,
the as-built Ti-6Al-4 V with a 90-lm layer thickness
achieved tensile ductility of 11% and a tensile yield
strength of 980 MPa.
The second article, ‘‘Defect, Microstructure, and
Mechanical Property of Ti-6Al-4 V Alloy Fabricated
by High-Power Selective Laser Melting’’, by S. Cao
et al. discusses the use of a high laser power (350 W,
800 W, and 1000 W) together with the accordingly
adjusted parameters to improve the SLM
productivity for Ti-6Al-4 V. The resultant microstructures
and defects were characterized. Increasing laser
power increased the build rate, but the formation of
defects needs to be properly managed. Further
systematic research appears necessary to fully
identify and understand the influence of high laser
power on the defect, microstructure, and
mechanical property of SLM-fabricated Ti-6Al-4 V.
Ma Qian and David Bourell are the guest editors for the invited topic
Additive Manufacturing of Titanium Alloys in this issue.
The third article by O. A. Quintana and W. Tong
deals with the ‘‘Effects of Oxygen Content on
Tensile and Fatigue Performance of Ti-6Al-4 V
Manufactured by Selective Laser Melting’’. The
oxygen content assessed was in the range of
0.110–0.164%. As-built Ti-6Al-4 V samples
containing 0.162%O exhibited very high tensile strengths
(1360.9 ± 5.5 MPa). After hot isotactic processing
(HIP), samples containing 0.164%O exhibited a
fatigue strength of 645 MPa compared with
595 MPa for samples containing 0.118%O. The
increase in oxygen content from 0.118% to 0.164%
did not show a noticeable impact on the fatigue
strength of notched specimens, which was in the
range of 175–180 MPa.
In the fourth article, B. Torries and N. Shamsaei
report on the ‘‘Fatigue Behavior and Modeling of
Additively Manufactured Ti-6Al-4 V Including
Interlayer Time Interval Effects’’. They investigated
the influence of different cooling rates, as achieved
by varying the interlayer time interval, on the
fatigue behavior of Ti-6Al-4 V specimens fabricated
via Laser Engineered Net Shaping (LENSTM) and
modeled the fatigue behavior using a calibrated
microstructure sensitive fatigue (MSF) model. It
was shown that the MSF model satisfactorily
predicted the fatigue behavior of Ti-6Al-4 V specimens.
The fifth article by J. Gockel et al. focuses on the
‘‘Trends in Solidification Grain Size and Morphology
for Additive Manufacturing of Ti-6Al-4 V’’. Using
analytical, numerical, and experimental
approaches, the authors provide a holistic view of
the trends in the solidification grain structure of
Ti6Al-4 V across a wide range of AM process input
variables. They concluded that within certain
processing ranges, it is possible to indirectly control
prior beta grain size through direct control of melt
pool size.
The sixth article is concerned with how to manage
powder bed fusion challenges including porosity,
surface finish, distortions, and residual stresses of
the as-built material. In this contribution, the
authors present a ‘‘Numerical and Experimental
Qian and Bourell (...truncated)