A Review on Status of Research in Metal

Additive Manufacturing

Ganesa Balamurugan Kannan and Dinesh Kumar Rajendran

Abstract Additive manufacturing is the essential technology in present near net

shape manufacturing scenario in the field of aerospace, automobiles, electronics,
medical implants, robotics, biomedical, etc., where near net shape manufacturing
plays a prominent role in dimensional accuracy. Additive manufacturing has
undergone drastic changes from plastics, polymers to metals. Additive manufac-
turing plays a key role in manufacturing of required components in short span of
time without any defect. In this paper, the different research aspects of additive
manufacturing are discussed on basis of two broad areas like design for manu-
facturing and process parameter control. The field of additive manufacturing has
brought the manufacturing to next level were it made production and product
development easier. An analysis is made on the published research articles and the
research gaps were found and finally the future scope in the field of metal additive
manufacturing is provided.

Keywords Additive manufacturing
Process parameter control
Design for

manufacturing

1 Introduction

Fabrication of near net shape metallic components is the attractive manufacturing

route for recent aeronautical, aerospace and automotive industries. The additive
manufacturing technology through additive manufacturing, 3D models can be
printed or fabricated directly using a laser source or electron beam source. The
metal additive manufacturing follows the principle of layer by layer printing of 3D

G.B. Kannan (&)
D.K. Rajendran

Adhoc Faculties, Department of Production Engineering, NIT,
Tiruchirappalli 600015, India
e-mail: gbmpondy@gmail.com
D.K. Rajendran
e-mail: dineshrd453@gmail.com

© Springer Science+Business Media Singapore 2017 95

D.I. Wimpenny et al. (eds.), Advances in 3D Printing & Additive
Manufacturing Technologies, DOI 10.1007/978-981-10-0812-2_8
96 G.B. Kannan and D.K. Rajendran

Fig. 1 Schematic
representation of additive
manufacturing process

objects. Additive manufacturing avoids tooling and minimizes the wastages. The
working principle of selective laser melting and electron beam melting is shown in
Fig. 1. The heating source of either laser or electron beam melts the successive
layers of metal powder bed and fused with each other to form a 3D finished
component. In this paper, the status of research in metal additive manufacturing
field has been discussed. The recent trend in metal additive manufacturing has been
focusing on two broad categories. Design for additive manufacturing and material
properties monitoring through manipulating the process parameters of selective
laser melting and electron beam melting processes are those broad categories.

2 Research on Design for Additive Manufacturing

The interesting feature of additive manufacturing is facilitating the design freedom.

However, to ensure the quality and reliability of additive manufactured products,
few design rules should be incorporated at the design stage itself. Ponche et al. [1]
have proposed a new numerical chain based on a new design for additive manu-
facturing methodology. This new numerical chain has been proposed for Additive
Laser Manufacturing of thin walled metal parts. The main objective of this work is to
minimize the gap between a CAD model and the corresponding manufactured
part. This new method involves part orientation, functional optimization, and
manufacturing path optimization as important steps. The part orientation step
involves the determination of design area. The functional optimization step involves
determining the optimal part geometry which is going to be the initial part geometry.
The final step in this methodology is to determine the optimized manufacturing
paths. Through these manufacturing paths, the manufacturing program is generated
along with the final part CAD model.
Guido et al. [2] explained about the extended design freedoms of technical parts
which provides them a new potential with the new project “Direct Manufacturing
Design Rules”. This research made the design benefits accessible to different user
groups. Hence a specific method was defined then design rules were developed for
A Review on Status of Research in Metal … 97

Fusion Deposition modeling, Laser sintering, and Laser Melting. The results for
suitable design for additive manufacturing were summarized in a design rule
catalog.
Klhan et al. [3] discussed about the geometrical freedom in design which is
utilized to largely improve the functionality of series products by substituting
conventional parts with additive manufacturing. Four criteria identified for redesign
are integrated design, individualization, lightweight design, and efficiency and it is
observed that a product, to be successful, needs to be improved in both a techno-
logical and economic direction. On the economic side, the investment in the change
of design and process has to pay off either by lower manufacturing costs or by
benefits during the lifetime of the product by fully utilizing the geometric freedom
in the redesign, impressive increases in performance can be realized. This opens
new perspectives in product development.
Cooper et al. [4] exploit the benefits of Additive Layer Manufacturing (ALM) in
the weight reduction of internal combustion engines inlet or exhaust valves. CT
scan technology was used as a reverse engineering tool. The hybrid manufacturing
route was preferred to reduce the manufacturing cost of the vales though ALM.
Further investigations are needed to join conventionally manufactured hollow stem
to the valve head manufactured by ALM by friction welding route.

3 Research on Effect of Process Parameters of Additive

Manufacturing Routes in Metallic Components
Manufacturing

Guijun et al. [5] implemented micro-LAAM (Laser Assisted Additive Manufacturing)

in layer by layer manufacturing of nickel-based super alloys IN100 which has poor
weldability that results in cracking and porosity, the defects were eliminated by
optimization and crack free deposition is achieved with minimal heat input, post
heated sample was observed with EBSD (Electron Back Scatter Diffraction) and
found three size of γ precipitates 0.5–1 µm, 0.1–0.3 µm, 10 µm and the volume
fraction of c to γ phase were 60–40 %. After grain refinement the tensile and yield
strength were found to be improved than the aerospace requirement specification 5397
for IN100 material.
Yanyan et al. [6] used the hybrid fabrication technique for fabricating TC11
titanium sample alloy for examining the microstructure, micro-hardness, and tensile
strength and found that the sample fabricated consist of three typical zone without
any defect in metallurgy the zones are called to be the laser additive manufactured
zone (LAMZ), the wrought substrate zone (WSZ), and the bonding zone and also
found LAMZ has superfine basket-wave microstructure which results in superior
tensile properties and HAZ caused by rapid cooling but no recrystallization or grain
growth found in HAZ due to the heat effect in α + β region micro transition zone
has coarse for k-like primary α and fine β microstructure and the TC11 sample
98 G.B. Kannan and D.K. Rajendran

fabricated has tensile strength of 1,033,713 MPa and elongation 6.8 ± 0.2 % and
the fracture occurs in substrate which shows mechanical properties of bonding zone
is better than the substrate. Micro-hardness in the transition zone was found to be
increased noticeably from the WS Z to the LAMZ
Ting et al. [7] fabricated TA2/TA15 graded structural material (GSM) using
additive manufacturing (LAM) process and examined the chemical composition,
microstructure and micro-hardness of the as-deposited GSM and found that
near-equiaxed grains was Widmanstätten α-laths microstructure where β phase
volume fraction increase and α phase volume fraction decreases. The part con-
taining large columnar grains was divided into four deposited layers with 3000 μm
in width was fine basket-weave microstructure, the graded zone micro-hardness
increases from the TA2 part to the TA15 part from 173 to 400 due to the solid
solution strengthening and grain boundary strengthening.
Yali et al. [8] simulated the temperature fields in additive manufacturing of
AlSi10 Mg by Selective laser melting (SLM) using FEM and investigated the effect
of laser power and scan speed on SLM and found cooling rate elevated slightly
from 2.13 × 106 to 2.97 × 106 °C/S when laser power increased from 150 to
300 W but when the scan speed increased from 100 to 400 mm/sit enhanced
significantly from 1.25 × 106 to 6.17 × 106 °C/s after repeating various combi-
nation it is found that a sound metallurgical bonding between the neighboring fully
dense layers was achieved at laser power of 250 W and scan speed of 200 mm/s,
due to the larger molten pool depth (67.5 lm) as relative to the layer thickness
(50 lm).
Konrad et al. [9] attempted to create light weight material for industrial appli-
cation, and the work focuses on low power fiber laser, feasibility of high strength
aluminum alloys, and custom developed powder system with different particle sizes
in Al and Cu/Zn particles and found that their size did not change during mixing
process. With this customized Al–Cu/Al–Zn composition able to create aluminum
alloy composition during laser melting No brittle hard oxidation upper layer was
noticed on melted lines, which is very promising for further development of multi
additive layer manufacturing process of reactive materials The manufactured
additive layers, characterized by a fine microstructure with homogeneously dis-
solved intermetallic phases in the metal matrix, has a big potential for usability
properties of the final manufactured product.
Processing of aluminum and it alloys through Selective Laser Melting is still
challenging. Aluminum alloy powders have poor flow ability, high reflectivity, and
high thermal conductivity compared to steels and titanium materials [10].
Moreover, difficulties in elimination of oxide layers, porosities, and cracks are
major challenges in SLM of aluminum alloy powders [9]. Most of the researches
are now focusing on SLM of AlSi10 Mg and AlSi12 Mg alloys (6000 series
alloys). The main process parameters are depicted in the following Fig. 2 [10].
Therefore, challenging in processing of aluminum alloy powders through additive
manufacturing still persists.
A Review on Status of Research in Metal … 99

Fig. 2 Process parameters

for SLM process

4 Conclusion

With the statistical analysis on research articles, the challenges faced in metal
additive manufacturing in design and process parameter control were brought out in
this paper. The results of research were analyzed and the research gaps were
identified and conclusions are presented.
• New design rules for metal additive manufacturing are derived for repeatability
and reliability of parts manufactured by additive manufacturing routes.
• Research on design for metal additive manufacturing is in nascent stage and
some of the research works are discussed. Specifically design rule for electron
beam additive manufacturing needs to be focused.
• Various research works on metallic components manufacturing through additive
manufacturing with various metals are briefly discussed
• Most of the research works are based on Laser additive manufacturing rather
than Electron Beam Melting. The wide gap in this area should be bridged with
appropriate research works.
• Metal additive manufacturing of aluminum alloys is still challenging and further
research works are needed in this area.

References

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100 G.B. Kannan and D.K. Rajendran

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