Temperature distribution in Additive Manufacturing involving Titanium Alloy (TI-6AL-4V)

This study focuses on the temperature distribution in additive manufacturing involving titanium alloy (TI-6AL-4V) and its impact on the mechanical properties. The research aims to evaluate the heat distribution during the manufacturing process and analyze the in situ measurements of temperature and distortion effects. The study also compares different scanning strategies and their effects on the final product. The results and discussion highlight the importance of understanding the thermal history and distribution in achieving high-quality parts.

Abstract
Numerous advantages and profits have been realized by the industrial sectors that use the
technology of additive manufacturing. These benefits are not comparable to the conventional
methods which include the use of subtractive manufacturing that is characterized by a little
volume of product prototyping. Majority of the industries that utilize this kind of technology
include aerospace and biometrics where the processes of manufacturing must be supported
effectively and accurately. As a result of the continuous use of this particular alloy of titanium
(Ti-6Al-4V), the research to advance on its application has been considered a very interesting
area of study. It has never been easy to have this kind of precious alloy formed by the other
conventional means.
Such institutions, as well as industrial set up that use Ti-6Al-4V, are very sensitive and
therefore very high levels of accuracy are required. This is the reason why a lot of studies have
been focused on the establishment of the fine properties of Ti-6Al-4V in order to ensure that its
mechanical values are enhanced as much as possible. This particular paper piece has
concentrated on the application of additive manufacturing on Ti-6Al-4V through use of
experiment while seeking to evaluate heat distribution.

Temperature distribution in Additive Manufacturing involving Titanium
Alloy (TI-6AL-4V)
INTRODUCTION
Most of the industries in clouding the aerospace, biomedical among others have taken a
keen interest in the use of additive manufacturing in the production of the tailored products.
Additive manufacturing that is commonly known as AM is one of the means of generating
complex- shaped components of metals which are appealing and conforms to the specific
applications. A metallic feedstock that may be in the form of a wire can be possibly be processed
to produce a greater volume by just an application of model data, computer numerical
control(CNC), directed energy and inert atmosphere[2].
The research of the project is set to begin with the definition of various experiments.
Every experiment will be defined with the utility to the overall objectives properly utilized. The
important ant measurements of the experimental in situ distortion together with the temperature
measurements that are carried out during Laser Powder Bed Fusion Additive Manufacturing
process will be considered key. The research employs an implementation of novel measurements
and techniques which allows for the in situ distortion. This will also allow for the measurement
of the temperature during the process of building[1].
The design of the measurement equipment has been done in a manner which allows for
taking of measurements while the powder bed system operations in a configuration of default
nature. The in situ measurement will be completed while comparing temperature for the
experimental build up and distortion. This will allow for the comparison of the use of the scan

and rotating pattern. The measurements that will be made as part of the study will eventually
demonstrate the increased distortion that will be a consequent of the application of the constant
scan pattern[1]. It is expected that the in situ measurement obtained to reflect what had been
previously measuring used in the distortion evolution in the entire process. The non-constant
distortion accumulation through the process of building will assist in the identification of the
problem with the present modeling techniques of LPBF.
The next stage will include the analysis of the in situ measurements of the temperature
for the Laser Powder Bed Fusion Manufacturing process and its distortion effects. It is to be
characterized by the measurements of at least five cases of experiments using the previously
constructed systems of measurements for the advanced analysis within the process of LPBF. The
research will involve making the comparison that utilizes the in situ measurements of the
temperature of distortion in the process of building[4]. The comparison is to be made while using
in situ measurements for Inconel ® 718 and Ti-6Al-4V with two varying geometries.
It will be very interesting to have a comparison between the experimental constructions
that have been produced through the machine component, EOS M280 machine, and the Reni
Shaw AM250. The in situ results of temperature and distortion components are built the common
machines of LPBF which assist in the identification of the weaknesses and strength of every
machine. The complexity of the implementation of mitigation techniques within distortion and
evolution will be properly illustrated with the result. The study will, therefore, focus on making
measurements which can validate future models of FE thereby providing a comparison for
variable build material and machine of the powder bed. In the evaluation of the experimental
validation of Finite Element Modeling for the Laser Powder Bed Fusion Deformation, there will
be the utilization of two experimental models[6]. One of the experiments utilizes a constant scan

pattern while the other one uses a rotating scan pattern.Both the two approaches employ the use
of cylindrical geometry and their design and construction are meant to provide measurements of
post-build distortion. The comparison of the two cases will, therefore, include use of the post-
build measurements of the parts
RESEARCH PROBLEMS
The Selective Laser Melting is considered to be one of the reliable additive
manufacturing processes which fall under the category of powder bed fusion process. The SLM
allows for the production of metallic parts with the complex geometry without the use of special
tooling and other multiple processes which characterizes traditional manufacturing processes.
The components that have been manufactured by the SLM processes normally have proper
quality and variable tastes as opposed to those which have been produced by subtractive
methods. In other words, the reliability control, and the quality of the parts is more difficult in
the case of the use of SLM that is a consequent of variation in the microstructure, manufacturing
defects like porosity and finally induced residual stress.
The quality of the additively manufactured parts has been studied by many scholars and
researchers. In such research works and investigation, the porosity as a factor has been found to
be responsible for the fatigue strength and resistance to crack propagation. The occurrence of the
porosity is normally as a result of excessive energy density that is responsible for the incomplete
melting of the powder or the excessive energy density which is responsible for the vaporization
of the most constituents of the alloy.
The main objective of this study is to predict the distribution of the temperature and the
induced residual stresses through consideration of different processes and strategies of the

scanning conditions[6]. The model has, therefore, employ an alloy of Ti-6Al-4V as a perfect
example considering that it is widely used in various applications including aerospace and
biomedical. In such applications, high quality and reliability are needed. Ti-6Al-4V is a material
that is biocompatible and has high resistance to corrosion, high strength to weight ratio and
finally high strength at high temperatures.
METHODOLOGY.
In this particular paper, there is the development of a finite element model to simulate the
process of SLM. The objective of such an undertaking is to handle the bigger part of the domain
size with the highest accuracy through consideration of the thermal properties of the thin layer of
the powder. In order to reach a compromise that is between the model accuracy and its
computational efficiency, the project proposes and subsequently utilizes an adaptive re-meshing
along with the scanning vector. Ideally the application of the fine mesh with the scanning vector
to capture high temperature accurately with the high-temperature gradient that has very minimal
re-meshing strategies[2]. The model will, therefore, be able to effectively handle the domain size
that is large. After the problem of the thermal, there is the creation of a new mesh to be used in
the prediction of the induced residual stresses in the analysis of the structure.
Powder Bad Fusion is one of the most commonly known methods of AM used in the
fabrication of the components of metals through an application of heat energy followed by a pre-
deposition of a layer that is called bed of powder feedstock. The source of the energy in the
process is normally generated from a focused laser or beam of the electron. In the case of an
application of laser, the component or the resultant product is called Laser-BPF. The application
of the radiation of laser that is also localized produces a very high flux of heat which is capable

of overcoming the latent heat of fusion of the powder. The product will, therefore, a micro pool
of the molten product. As the laser moves away from the already molten point, solidification
begins taking place. The process is actually repeated to assist in the formation of multiple solid
tracks. In this particular paper, there is the development of a model of the transient thermal finite
element of a selective laser melting for Ti-6Al-4V by the use of ANSYS software[3]. This
particular software has been recommended for the prediction of thermal history and the size of
the melt pool. There is remapping of the thermal solution to the structural problem. This has also
been done to assist in the prediction of the induced residual stress of the items. This particular
model that has thermo-mechanical properties is capable of handling a practical domain size with
effective efficiency of computational analysis[5]. This is achieved through the development of
remapping and mashing techniques that is capable of adapting with the scanner vector.
RESULTS AND DISCUSSION
The research involved the use of a material model which considered the material phase changes
and transitions. This was basically reflected in the powder melting and solidification. There was
a definition of two temperature dependent material model for both the solid materials and
powder and their behavior was found to be similar beyond the temperature for melting. The
calculation of the powered thermal conductivity was done based on Childs et. al.In such
calculation, the powder thermal conductivity was found to be a function of relative density and
thermal conductivity of the solid.
.There was the calculation of the volumetric heat capacity for both powder and solid from the
temperature-dependent density and temperature –dependence specific heat. The properties of the
thermal have been illustrated in the figure below alongside the nonlinear properties. The

assumption made is that the thermal and mechanical properties are isotropic. The possible
changes in the properties of the material due to other parameters are duly ignored. For the case of
the single bead model, there was a setting of the initial temperature at 25 degrees.
There was an assumption of a preheated powder to the temperature of 400 degrees for the case of
the models with scanning strategies. In the case of the mechanical problem, there was a set of
thermal expansion and elastic modulus as the very low quantities or values after the temperature
of melting. This was done so as to ensure that thermal expansion had negligible effect. The
model of material plasticity is actually a temperature dependent multilinear isotropic hardening
from most of the experimental data[1].
Another important component that has been found to be important is the residual stresses. This
has been found to be under the influence of specific parameters like scanning strategy, building
directions and orientations and finally the temperature of the powder bed. It is however still no
proper understanding of the effects of the scanning strategy on the residual stress. In terms of the
strength and life of the products, parts microstructure was found to be influential and it also
affected by the scanning strategy as well as the other parameters of processing.
Despite the fact that the techniques of the post-processing like the heat treatment and hot
isostatic pressing can assist in alleviating some of the problems that have been aforementioned,
they cannot eliminate them completely especially porosity which is being reduced by
undetectable range. Prediction of the thermal history of the part during SLM will be very
important to understand how the quality of the parts is influenced by the parameters of the
process[6]. The numerical methods that characterize the process of SLM assist in the provision
of useful tools. These tools are capable of identifying the temperature history and distribution,

part distortion and induced thermal stress. It can also help to optimize the parameters of the
processes in achieving proper mechanical characteristics.
CONCLUSION
It is important to note that prior to the use of these components, their quality and integrity
must be checked and reliably confirmed. This can be achieved through the determination of the
feedstock process property performance relationship which is normally inherent to the specific
material. By so doing, the same efforts can be expedited[3].Considering that most of the
microstructure and macrostructure of the metallic parts of AM process are coupled directly by
the use of heat during their manufacture, the relationship of the process property can be
determined through observation and quantification of the part temperature and other heat release
requirements during the process of additive manufacturing. The input of laser heat flux is
represented by a heat source of Gaussian. The study took into the assumption that only elements
that are exposed to the surface will be influenced by the laser beam.

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