Project and analysis (2)

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Student Name : Kareem
Student ID :
UoS/UCLAN ID (Delete which ever unnecessary) :
Title : Investigation of microstructure and microhardness on fiber laser welded
zincalume after laser surface modification
Date of Submission :
Supervisor:
Date:
Module Leader:

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TABLE OF CONTENTS
TABLE OF CONTENTS.................................................................................................ii
LIST OF TABLES.............................................................................................................iv
LIST OF FIGURES..........................................................................................................v
LIST OF SYMBOLS ......................................................................................................vi
TABLE TITLE PAGE
CHAPTER 1: INTRODUCTION.....................................................................................1
1.1 BACKGROUND OF STUDY....................................................................................1
1.2 IMPORTANCE OF STUDY..................................................................................... 2
1.3 PROBLEM STATEMENT........................................................................................ 3
1.4 RESEARCH MOTIVATION.................................................................................... 3
1.5 RESEARCH OBJECTIVES...................................................................................... 3
1.6 SCOPE OF RESEARCH AND LIMITATIONS ....................................................... 4
1.7 THESIS STRUCTURE.............................................................................................. 4
1.8 GANTT CHART……………………………………………………………………5

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CHAPTER 2: LITERATURE REVIEW.........................................................................6
2.1 INTRODUCTION..................................................................................................... 6
2.2 ADVANCED TECHNOLOGIES AND THERMAL JOINING PROSSES ..............9
2.3 TYPES OFLASER WELDING .............................................................................. 12
2.3.1 CO2 LASERS ................................................................................................... 12
2.3.2 FIBER LASER WELDING.............................................................................. 13
2.3.3 ND:YAG SOLID-STATE LASER................................................................... 14
2.3.4 EXCIMER GAS LASER.................................................................................. 16
2.3.5 DIODE LASERS.............................................................................................. 16
2.4 PRINCIPLE OF LASER GENERATION............................................................... 18
2.4.1 SPONTANEOUS EMISSION......................................................................... 18
2.4.2 STIMULATED EMISSION ............................................................................ 18
2.4.3 AMPLIFICATION ........................................................................................... 18
2.5 LASER WELDING CONFIGURATION............................................................... 19
2.5.1 BUTT WELDS................................................................................................. 19
2.5.2 FILLET LAP WELDS……….….....................................................................19
2.5.3 SPOT WELDING…………….........................................................................20
2.5.4 PULG/SLOT WELD…………........................................................................21
2.5.5 EDGE FLANGE WELD………………………………………………...…...……22
2.5.6 OVERLAP WELD………………………………………………………………….……22
2.6 INDUSTRIAL APPLICATIONS OF LASER WELDING…………………….…22
2.6.1 LASER WELDING IN AUTOMOTIVE INDUSTRY.…...............................23
2.6.2 LASER WELDING IN AIRCRAFT INDUSTRY……………………….….25
2.6.3 LASER WELDING IN STEEL INDUSTRY………………………………..26
2.6.4 LASER WELDING IN SHIPBUILDING INDUSTRY……………………..27
2.6.5 LASER WELDING IN MEDICAL INDUSTRY…………………………....27
2.7 STATE OFTECHNIQUE…………………………………………………………28
2.8 COMSOL MULTIPHYSICS……………………………………………………...29

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CHAPTER 3: METHODOLOGY.................................................................................. 32
3.1 FLOWCHART........................................................................................................ 33
3.2 MATERIAL PREPARATION…………………………………………………….34
3.2.1 ZINCALUME STEEL……………………………………...………………...34
3.2.2 SAFETY REQUIREMENT……………………………………………….…36
3.3 JIGS AND FIXTURES............................................................................................ 36
3.4 CUTTING PROCESS………………………………………………………….….37
3.5 GRINDING PROCESS……………………………………………………………37
3.6 METALLURGICAL TESTING SETUP………………………………………….38
3.7 DIGITAL MICROSCOPE…………………………………………………………39
3.8 SCANNING ELECTRON MICROSCOPY……...………………………………..40
CHAPTER 4: NUMERICAL ANALYSIS AND SIMULATION ................................... 41
4.1 NUMERICAL ANALYSIS ................................................................…………...42
4.2 MATHMATECIAL FORMULATION………………………………………….43
4.3 MODELING AND MESHING………………………………………………….45
4.4 RESULT AND DISCUSSION…………………………………………………..46
CONCLUSION……………………………………………………………………………………..50
REFERENCES……………………………………………………………………………………..51
APPENDICES
APPENDIX A Project schedule -Gantt Chart

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LIST OF TABLES
TABLE 2.1: COMMON ADVANTAGES AND DISADVANTAGES OF LASER WELDING………8
TABLE 3.1: PARAMETERS SELECTED IN THE STUDY………………………………………….35
LIST OF FIGUERS
FIGURE 2.1: SCHEMATIC OF LASER BEAM WELDING PROCESS…………………………………….11
FIGURE 2.2: CO2 WELDING SYSTEM……………………………………………………………………..13
FIGURE 2.3: FIBER LASER WELDING SYSTEM ………………………………………………………...14
FIGURE 2.4: Nd:YAG SOLID-STATE LASER………………………………….………………………….15
FIGURE 2.5: MULTI-SENSING SYSTEM FOR HIGH-POWER DISK LASER WELDING PROCESS…17
FIGURE 2.6: BUTT WELDS…………………………………………………………………………………19
FIGURE 2.7: FILLET LAP WELDS………………………………………………………………………….20
FIGURE 2.8: SPOT WELDING……………………………………………………………………………….20
FIGURE 2.9: PULG/SLOT WELD…………………………………………………………………………….21
FIGURE 2.10: EDGE FLANGE WELD……………………………………………………………………….22
FIGURE 2.11: PART OF CAR BODY FOR DOORS…………………………………………………………25
FIGURE 2.12: CO2 LASER WELDING……………………………………………………………………….26

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FIGURE 3.1: METHODOLOGY FLOW CHART……………………………………………………………..33
FIGURE 3.2: CROSS SECTION OF ZINCALUME………………………………...…………………………34
FIGURE 3.3: JIGS AND FIXTURE…………………………………………………………………………….36
FIGURE 3.4: CUTTING MACHINE ……………………….…………………………………………………37
FIGURE 3.5: GRINDING MACHINE…………………………………………………………………………38
FIGURE 3.6: DIGITAL MICROSCOPE……………………………………………………………………….39
FIGURE 3.7: SCANNING ELECTRON MICROSCOPY……………………………………………………..40

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LIST OF SYMBOLS
3D : THREE-DIMENSIONAL
BM : BASE METAL
CO2 : CARBON DIOXIDE
CW : CONTINUOUS WAVE
EDX : ENERGY DISPERSIVE X-RAY
FZ : FUSION ZONE
HAZ : HEAT-AFFECTED ZONES
LASER
: LIGHT AMPLIFICATION BY
STIMULATED EMISSION OF
RADIATION
LBW : LASER BEAMWELDING
OM : OPTICAL MICROSCOPE
DM : DIGITAL MICROSCOPE
SEM : SCANNING ELECTRON MICROSCOPE

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CHAPTER 1
INTRODUCTION
1.1 Background of study
The most realistic and versatile joining method applicable to the construction of products
in every industrial field is welding. Furthermore, the high-power intensity heat source is the laser.
An advanced process for joining materials with a high power, energy intensive laser beam. The
power intensity of a laser beam equivalent to that of an electron beam is much greater than that of
an arc or plasma. As a result, a deep and narrow key hole is formed during welding with a high-
power laser or electron beam, and a deep and narrow penetration source can be produced
effectively. (Katayama, 2013)

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Because of the high energy density, the main advantage of laser welding is the capability
to melt the area of edges on the joints without affecting the greater area of the part (Katayama,
2013). The consequence is a thermal joint with the smallest distortion that do not require any sort
of finishing the operation. On the other hand, because to relatively low energy radiation by the
laser, the thin sheets can be welded. When high penetration is required, high energy density allows
more energy to be concentrated at the joint that is to be welded, giving the resulting compound a
narrow and high penetration shape. Automation and cleaning are very fast and easy compared to
other methods (Aitzol, 2011)
The nature of the laser beam allows you to focus on a small spot, which allows you to
achieve a high-power density. This advantage is the main feature of representing its potential as a
welding process. In addition, the high production speed can be achieved with the laser beam source
is attractive for many applications. Regardless of the welding method, it is well known that fusion
welding usually involves heating the two parts together, which can lead to modifications with loss
of material properties. In other words, the properties of the region around the weld (HAZ) include
a change in hardness, a decrease in tensile strength, impact strength, etc. (Publishing, 1992).
1.2 Importance of Study
The importance of this study is in finding methods of welding Zincalume steel in the
configuration of overlap-joint. In the past, research and studies have focused on the use of high-
intensity lasers for metal welding, but in this research, the similar process of joining Zincalume
steel are welded using low powered fiber laser. Fiber laser is a new technology that developers are
focusing on. This technology takes less time to weld materials, reduces production time and
improves overall productivity and profit (P.Janasekaran, 2017).

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1.3 Problem statement
Panels fabricated from ZINCALUME Steel will provide many years of trouble-free
service when properly designed, installed and maintained. The key to obtaining all the benefits of
the corrosion resistant coatings applied to steel used in roofing, siding and rainwater items lies in
correct material selection, good handling and installation practice, and sensible maintenance. Other
than that, the welding method used determines the quality of the final product. Using fiber laser
welding is expected to provide many benefits such as reduced costs, better efficiency and higher
quality welds.
1.4 ResearchMotivation
Over the past decade, the use of source lasers has significantly increased productivity and
reduced costs in many areas. According to New Zealand, zinc steel is welded using gas arc
welding, manual arc welding and resistance welding. However, fiber laser welding was not used
for welding ZINCALUME steel. This is the main motivation for this study to evaluate the effect
of laser welding parameters on the microstructural properties of low-energy zinc-fiber laser steels.
1.5 Research Objectives
The main goal of this research is developed by method of Overlap-joint configuration with
fiber laser welding without hampering the quality. Primarily in this project report that to study the
influence of laser welding parameters of Zincalume steel by flowing specific measurement factors
which can be stated as
 To Evaluate microstructure of Zincalume after laser surface modification.
 Study about microstructure of welded zincalume after laser surface modification.
 Study about microhardness of welded zincalume after laser surface modification.

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1.6 Scope of Research
The scope of this research is to weld Zincalume steel similar join in an over-lap joint
configuration by using low-power fiber laser. The power of laser machine can be operated up to a
power of 300 W and the recommended range of power to be use is from 220 W to 260 W. the
thickness of the Zincalume panels is 0.62 mm. After the experiment, metallurgical testing setup
will be done such as cold mounting, cutting, grinding and polishing, the samples will be examined
through Scanning Electron Microscope and Energy-dispersive X-ray. The data and results then
will be collected to discuss and obtain the micro-structural properties.
1.7 Thesis Structure
This thesis consists of 5 chapters: introduction, literature review, methodology, results
followed by discussion, conclusions and recommendations.
Chapter 1 describes the important information about research and its impact. The purpose
and problem statement are emphasized.
Chapter 2 describes a literature review of standard welding techniques used as joining
technology. General types of laser welding configurations are described in detail. In addition,
various types of laser machines used in the industry are identified and described. Finally, laser
welding applications and modes are also addressed. Finally, summary related to recent studies is
provided
Chapter 3 describes each of the experimental methods used in this study.
The materials used, equipment and testing equipment are also described.

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CHAPTER 2
LITERATURE REVIEW
2.1 Introduction
Recently, zincalum stainless steel laser welding has attracted great interest in the industry
due to its wide application in petroleum refining stations, power plants, pharmaceutical industry
and homes. Therefore, mechanical properties should be checked to obtain good welded joints.
Welding process should be optimized with appropriate mathematical models. In this research,
tensile strength and impact resistance with the common operating cost of the laser. In fact, the laser
is a light amplification with stimulated radiation emission. The laser is a powerful beam that is
produced by concentrating light in a tube repeatedly until it emerges as a narrow, straight,
monochromatic beam of light. Although the concept of producing a laser beam was given in 1958,

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the practical laser beam was created in 1960 by an American scientist Theodore Maiman. In his
experiment, Maiman used a 2cm long, 1 cm diameter ruby crystal. The ends were coated by silver
so that one end became fully reflective while the other became semi-reflective. The ruby was then
spiraled with a lamp that emitted white light and thus triggered the laser mechanism (Katayama,
2013).
Expert design software was used to create the design matrix and analyze experimental data.
Relationships between laser welding parameters (laser power, welding speed and focal position)
and three responses (tensile strength, impact resistance and joint operating cost) have been
established. In addition, optimization capabilities in expert design software are used to optimize
resource design. The developed mathematical models were tested for proficiency using variance
analysis and other proficiency measurements. In order that improve efficiency and minimize the
total operating cost, the most appropriate resource conditions were determined in this research.
The chromium gets excited by the white light from the spiral bulb. The electrons of the
chromium get excited and move to a higher energy state. After a while, the electrons come back
to their original state and as a result of a which they emit ruby-red light. A part of this light is
reflected back and forth by the two mirror surfaces within the crystal, which then excite more
electrons that give off the more ruby-red light. This process continues until the ruby is exhausted
and a strong and powerful beam of monochromatic light emerges from the crystal that formed term
as the laser. This high energy, straight beam of light is used in many applications. One of its uses
is fusion welding (Katayama, 2013).
The main challenge for the manufacturer is how to choose the process input parameters
that will create a perfect welding connection. Traditionally, defining the welding input parameters
for new welded products to produce a weld joint according to the required specifications is a time-
consuming test in conjunction with the effort to develop an error together with the weld input
parameters selected by the engineer's skill. or machine operator. The source is then examined to

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determine if it complies with the specification. Finally, the selected parameters will produce a weld
joint close to the required specification. Also, what is often ignored or not achieved are optimized
source parameter combinations. In other words, there are alternative combinations of ideal source
parameters that can often be used if they can be determined.
It is important to investigate mechanical properties to describe the performance of any
welding joint. Tensile strength and impact resistance are among the most vital mechanical
properties. In this study, we will investigate tensile and impact strength. In addition, in this
investigation, the operating cost of the solder joint was taken into account to optimize (Charles,
1992).
Table 2.1: Common advantages and disadvantages of laser welding
Advantages Disadvantages
Welding in places that cannot be
accessed easily
Rapid cooling rate may cause cracking in some metals
Small heat-affected zone (HAZ) High capital cost for equipment
Low distortion rate Optical surfaces of the laser are easily damaged
High welding speed High maintenance costs
Little deformation
Metals larger than 19mm in thickness, are difficult to
weld
Possibility for weight reduction
low energy conversion efficiency, generally less than 10
percent.
Low heat input Laser welding machines are expensive
Process can be automated well
Welding pass flash set there maybe has pores and
embrittlement trouble.

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2.2 Advanced technologies and thermal collection joining prosses
The fast-developing technologies are pushing the welding technologies to improve in areas
of efficiency and productivity. As the industries are realizing the need to manufacture more energy-
efficient products, they are looking towards lighter and stronger metals and alloys. One of the
challenges for welding technology is to be able to weld such material and to be able to weld
different kinds of metals and alloys. Moreover, industries are also interested in reducing their
energy consumption. For this purpose, filling material required is reduced and lap joints are
replaced with but joints. This yields a lightweight product as well. The goals of the researchers,
therefore, are to find a solution that is energy efficient and can use lesser material (Kashaev, 2019).
One idea to tackle the above-mentioned challenges is to combine different welding
techniques and leverage on the advantages of the both. The use of laser beam welding alongside
metal arc welding has proven successful for industrial use. The advantages gained from laser
welding include energy-dense beam, increased penetration depth, and feed rate. While those of arc
welding technique include reduced welding defects and high gap bridging ability. When combined,
these processes can be used to weld even products with thick walls. Moreover, using these
processes for welding aluminum products can reduce the number of fluxing agents, which in turn
reduces the number of process steps and simplifies the process chain (Kashaev, 2019).
In laser welding, two metals are fused or welded together using a laser beam. It is, therefore,
categorized as a fusion welding technique. Two metal pieces are held together, and a laser beam
is hit at the cavity between them. The energy of the laser beam should be high enough to be able
to meet the two metal objects so that the molten metal fills the gap between them. Then the melted
metals can cool down and they then solidify back again to form a joint. The resulting joint is strong
and durable. This type of fusion welding technique is efficient and is suitable for industrial use as
it can be automated. Laser welding is mightily utilized in the automotive industry (Czerwinski,
2011).

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The basic principle of laser formation is that when electrons are provided with energy, they
absorb it and proceed to the higher energy state and it is so called the excitation of electrons. When
these electrons return to their original energy state emits a photon or energy packet. When many
such photons are concentrated using stimulated emission, a laser beam is produced (Bansal, 2016).
The basic parts for a laser welding setup as shown in figure 2.1 are:
o Laser Beam Machine: The main part of laser welding is the laser itself, which is
generated through a laser machine.
o Energy Source: The laser machine needs to be powered using a high voltage power
source.
o Computer-Aided Manufacturing (CAM): CAM is used to control the laser welding
process through computers and software. It integrates the parts of the laser machine
with the computers to provide better accuracy and efficiency.
o Computer-Aided Design (CAD): CAD is utilized to design entire welding process
and the product on which the welding needs to take place.
o Shielded Gas: To keep the product from getting oxidized during the high energy
welding process, a shielding gas can be used to isolate it.
Figure 2.1: Schematic of laser beam welding process (Czerwinski, 2011)

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The laser machine does not produce a continuous laser beam and it is designed to emit a
set number of pulses of laser with a second. The beam hits the metal surface and melts and
vaporizes some part of it, this is termed as keyhole effect. The melted metal then flows into the
keyhole and solidifies. This forms a joint. This welding process can take place with the help of
fillers or even without it. The main advantages of the laser beam welding include reduced amount
of heat used that in turn causes less damage to the neighboring material. Moreover, it produces
low part distortion, higher flexibility in tooling design and produces no slag nor spatter
(Czerwinski, 2011).
2.3 Types of Laser Welding
There are various laser welding systems available now. Industries are already using the
fiber, Nd:YAG and CO2 lasers. Low power (Nd:YAG) laser is extensively utilized in the
electronics industry. Enhanced high-power and power-density diode lasers are now available for
deep penetration welding production technology (Katayama, Laser welding, 2017).
2.3.1 CO2 Lasers
The CO2 lasers operate with a wavelength of 10.6 μm and a power range of 1.5 to 6 kW,
but some operate at constant power levels of 10 kW or more. The efficiency of energy transfer
from the laser beam to the workpiece can be as much as 0.8, but the power absorption efficiency
of the metal laser beam is as high as 15%. The optical system consists of a Zinc selenide (ZnSe)
lens and a mirror. This Laser is used for high-speed sheet welding. Figure 2.1 show CO2 welding
system (Walsh, 2002).

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Figure 2.2: CO2 Lasers (Jerncontoret, 1995)
2.3.2 Fiber Laser Welding
The main difference between the fiber laser welding and CO2 welding is the wavelength
of radiation. Wavelength equal to and smaller than 1.07 μm can be achieved in fiber laser welding,
which is an order smaller than that of CO2 welding. The power range of fiber laser welding ranges
from 1 to 100 kW. Moreover, it has an efficiency of 30% that is more than twice that of CO2
welding. These advantages make it a very suitable candidate for metal welding. Furthermore, using
fiber optics as a source to generate a laser beam is more reliable than using optical mirrors that
require special systems to provide a similar level of reliability. This stability, therefore, makes the

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use of laser welding more flexible and expands its uses to areas that were previously difficult to
access (Grezev, 2015).
Figure 2.3: Fiber Laser Welding (TaiQi, 2009)
2.3.3 Nd:YAG Solid-State Laser
In the YAG welding system, the radiation wavelength is 1.06 µm and the power of pulses
can range from1 to 10 kW. Today, lasers that can give power up to 3 kW continuously are also
available in the market. The benefit of using smaller wavelengths is that they are more easily
absorbed into the metal surface (Zhang, 2018).
The YAG welding system can give efficiency of 3-5%. The laser beam produced can travel
through flexible glass fibers giving it an edge over CO2 laser systems. Thus, YAG welding can be
done using articulated robot arms and can be used for 3D operations. Moreover, it gives higher

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flexibility, lower costs and higher accessibility. CO2 lasers, however, are produced using a
complex optical mirror system. By using fiber optics and optical lenses, well-defined size and
angular radiating laser cone with an even energy distribution are produced. On the other hand, the
CO2 laser is produced using a mirror system and hence gives a Gaussian energy distribution.
A single laser beam can be used at multiple locations using a dielectric splitter that can
split the laser beam into multiple beams and hence divides the energy as well. Electrooptical or
mechanical deflectors can also be used to multiplex a beam to different locations. All this is done
using optical fibers. The ability to spot weld different locations simultaneously provided by Nd:
YAG has made it an attractive choice in the electronics industry. YAG reduces stress and distortion
on the product and is highly efficient. Using the above-mentioned techniques, the temporal power
profile of every pulse can also be shaped according to the requirement. This is possible for pulse
rates of up to several kilohertz (Walsh, 2002) (Zhang, 2018).
Figure 2.4: Nd:YAG Solid-State Laser (Zhang, 2018)

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2.3.4 Excimer Gas Laser
The Excimer Gas Laser has wavelength in the ultraviolet region. They are designed to
create short high-power pulses with power levels reaching above 100 MW and duration tens of
nanoseconds. Such laser systems have efficiency of 2-4%. The optical system for these lasers is
difficult to create as few elements are transparent to radiations of this wavelength. The optical
elements have a low life-time. A typical excimer gas laser is a rectangular beam with a 2:3 aspect
ratio. The beam is of low quality and is emitted in both directions. For such a beam K<0.01. As
evident, these beams are difficult to focus on a small area. One application of excimer gas laser is
(Ewing, 2018).
2.3.5 Diode Lasers
The diode lasers have a wavelength that lies in the infra-red region which is suited for
industries looking to weld metals like aluminum that has a better absorption coefficient in this
region. Therefore, diode lasers have this advantage over CO2 and Nd: YAG lasers. Moreover,
diode lasers have higher efficiencies of up to 50%. In order to generate a powerful laser beam
using a diode laser, several emitting diodes are required. The radiation from all these diodes is then
shaped and combined to form a strong laser beam. Because of (Eq. 2.1) the nature of diodes, there
is a need to develop micro-optical elements and diffractive optical elements (Deyong, 2014),
2014) (Walsh, 2002).
The main disadvantage s of diode lasers as compared with (CO2) and (Nd: YAG) lasers
are the lower power and beam quality. The diode lasers available can reach up to 2.5 kW power.
Therefore, for diode lasers to be suitable for deep penetration welding, they need to improve on
these areas. One of the advantages of the diode laser is their compact size; for a multi-kW laser
the size is equal to a small box (Deyong, 2014).
Since a diode laser is significantly smaller in size and has lower weight as compared to the
(CO2) and (Nd: YAG) laser of the same power, it is suitable to be used on robot arms. Moreover,
diode lasers have a longer lifetime, about 5000 to 10,000 hours, and lesser cooling requirements.

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Advancement in the technology cannot reduce the size of these lasers significantly, as it is limited
by the cooling requirements (Walsh, 2002).
Figure 2.5: Multi-sensing system for high-power disk laser welding process (Deyong, 2014)
2.4 Principle of lasergeneration
The generation of a laser beam is a three-step process in which steps occur almost
instantaneously.

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2.4.1 Spontaneous emission
The pump source energizes the environment, thereby stimulating atoms in the laser
environment, so the electrons inside the atoms are temporarily raised to higher energy states.
Electrons held in these excited states cannot stay there forever and go down to a lower energy
level. In this process, the electron emits a photon and loses excess energy from the energy of the
pump. The photons produced by this process, called self-emission, are the seeds of laser
production.
2.4.2 Stimulated emission
Photons emitted by spontaneous emission collide with other electrons in higher energy
states. This occurs in a very short time due to the speed of light and the density of excited atoms.
The incoming photon "hits" the electron at a lower energy level than the excited state, and forms
another photon. These two photons are sequential, that is, they move in phase, at the same
wavelength and in the same direction. This process is called excited radiation.
2.4.3 Amplification
Photons spread in all directions. However, some move along the laser medium to hit the
resonator mirrors that will be reflected from the medium. Resonator reflectors define the preferred
amplification direction for the excited emission. For excitation to occur, the percentage of atoms
in the excited state must be higher than lower energy levels. This "reversing the population" of
more atoms in the excited state leads to the conditions for laser production (James, 2012).
2.5 Laser Welding Configuration
Using laser welding, many different joint geometries can be made as this is a non-contact
process. The common joint designs in welding are as follows:

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2.5.1 Butt Welds
A butt weld is the configuration of components that can be assembled on the same plane.
Tailored blanks automotive space is a typical application of this type of welding. These parts are
associated with the melting of the edge pressed to minimize space. Edge adjustment is required
primarily for welding applications of tailored blank (<2.0 mm or <0.125 inches): the beam moves
through gaps passing approx. 10% of the thickness of the material will cause poor welding. For
welding coated materials, If the edges are not coated, welding them does not cause any trouble
(Chen, 2010).
Figure 2.6: Butt Welds
2.5.2 Fillet Lap Welds
In fillet lap welding, the parts overlap and the edges of one part melted to join the surfaces
of the other part. The preparation of welding using this method is intended to join clean metal
surfaces and requires removing the oxide and surface layer from the joining area.
Figure 2.7: Fillet Lap Welds

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2.5.3 Spot welding
The resistance spot welding is a type of electrical resistance welding used to weld various
sheet metal products in a process where the contact points of the metal surface are combined with
heat from the resistance. electrical current.
Figure 2.8: Spot welding
2.5.4 Plug / Slot weld
A plug welding is used to join the two pieces of metal using a soldering iron. Combining
the parts, a hole is drilled in the upper part and placed under it. Then, by holding the two parts
together, a bead is made by inserting a bead into the drilled hole. While performing auto body
repairs, this type of welding is often used when replacing body panels. The result is similar to a
point source because it is circular. When two different metal thicknesses are combined, the plug
welding is usually the choice of welding. Soldering may occur by welding the thin upper part to a
thicker lower part. While this type of solder is sometimes used to connect two thick steel sheets, it
is primarily a thin source of metal. When making one, welders should be careful not to burn the
bottom metal part. Soldering is also used when welding a bar to a pipe. When suitability is such
that the rod bolt or pin fits into a hollow tube, a hole is drilled into the tube and a plug weld is used
to fix the rod inside. Sometimes, this method is also used when welding thin exhaust pipes in a
vehicle. After the exhaust sections are installed, welding is done using this method to fix the piping
system under the vehicle (Kannan, 2018).

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The socket welds between two elements, one containing a long hole to which the other
element is exposed; the hole is partially or completely filled with weld metal so that it joins the
two elements; one end of the hole may be open.
Figure 2.9: Plug / Slot weld
2.5.5 Edge Flange Weld
In an edge marginal welding, the welded part is bent to provide a peripheral portion, which
is then joined at the edge. Again, here, a good fix up is significant.
Figure 2.10: Edge Flange Weld
2.5.6 Overlap Welds
In the application of overlap welds, one part is placed on top of the other. A widespread
application of this type of weld is laser spot welding. Most importantly, and in the case of lap
welding, the surface of the component to be joined should not have rust and a surface layer.
Installation requirements are secondary. The beam must be strong enough to penetrate the
thickness, which is approximately equal to the total thickness of the material. Coating materials

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that cannot escape from the overlapping area (such as zinc) cause serious problems and can cause
voids and other inclusions in the weld. This can be avoided by leaving a small space (0.05-0.2
mm) between the assembled parts. The vacuum allows the coating to evaporate and leave the weld
without degrading the quality of the joint (Chen, 2010).
2.6 Industrial applications of laser welding
Laser welding has gained popularity in the industries because it is highly suitable for
automation and can be used with robots. It is widely used in areas of mass production like
shipbuilding, automotive industry, electronics, and medical industries. The fact that it can be
completely controlled through computers makes it attractive for processes and products where
accuracy is key. Industrial lasers also ensure high stability and reliability. Moreover, laser welding
comes with many customizable features making them well suited for many applications such as
micromachining (Moskvitin, 2013)
Developed in the mid-1970s, multi-kW class high power CO2 lasers capable of welding
key holes have been developed since then to apply CO2 laser welding to various lasers. Industrial.
This section presents some examples of industrial applications.
2.6.1 Automotive industry
Laser welding is an especially attractive technology for the automotive industry as it can
weld pre-manufactured parts together with minimum alteration to the surrounding area with its
concentrated heat transfer. It is used to weld transmission parts, engine components, solenoids,
alternators, fuel filters, and injectors, as well as air conditioning components (shin, 2017).
From the late 1970s to the 1980s, the application of the CO2 laser source in the automotive
industry began. Various powertrain, including drive gears, hubs and axles, have been welded with
CO2 lasers (Petring, 2004).

22
High efficiency, low heat input and low distortion are the main advantages of the laser
source over other processes. In these applications, CO2 lasers are still used. It is mightily utilized
in production of automotive body parts such laser welded cavities, doors, front and side panels,
side beams and wheel arches.
As shown in Figure 4, flat metal sheets of different size, strength and coating are combined
with the laser source before forming and straightening. Mixing of different sheet metals allows for
a reduction in weight, number of components and total production cost and improved shock energy
management. This technique has been used since the mid-1980s. Most linear welding lines are
equipped with 5-10 kW CO2 laser. On the other hand, Nd: YAG, fiber or disk lasers are mainly
used in nonlinear welding. The application of laser welding in the shop began in the mid-1980s.
Car companies installed C02 class 5 kW lasers to weld the bodywork to white, such as joining the
ceiling to the side frames. However, the use of CO2 lasers decreased in the late 1990s due to the
installation of high-power Nd: YAG lasers with robots capable of 3D laser welding. Installation
of the remote laser source began in the early 2000s to produce body components. In this system,
the laser point is moved quickly with high speed scanning mirrors to weld some parts very quickly.
A high-quality beam laser is required to cover the large welding area with a long focal length,
typically longer than 1 meter. First, a CO2 slab laser was used to obtain a high-quality beam laser
beam. Reduced touch time and high efficiency are the main advantages. Due to the advancement
of high-power discs and high beam quality fiber lasers, a new remote welding system has been
developed combined with the robot. A more flexible and faster source was obtained using fiber
laser and disk. This system is called 'remote source on the go' and is widely used.
The laser welding process is reproducible and easy to automate. These properties make this
process ideal for high-productivity processes such as those used in the automotive industry. Laser
welding offers many advantages and benefits compared to traditional welding processes and can
significantly reduce costs while improving performance and manufacturing quality (Fernandes,
2017).

23
Figure 2.11: part of car body for doors (Fernandes, 2017)
2.6.2 Aircraft industry
In the early 2000s, Airbus applied stringer CO2 laser welding to the cladding plates for
aircraft body panels, this was achieved through improvements in weldable Al-Mg-Si-Cu alloy laser
welding systems. Instead of conventional riveting, beams are attached to the outer layer
simultaneously by laser welding on both sides, as shown in Figure 2.28. Filling wire of Al-12% Si
is used to prevent hot cracking. Weight reduction, high efficiency, improved corrosion resistance
and high performance are the main advantages of replacing the traditional riveting process by laser
welding (al, 2002); (al V. e., 2004).
Figure 2.12: CO2 laser welding

24
2.6.3 Steel industry
Since the early 1980s, the steel industry has installed 5-10 kW CO2 lasers to weld hot or
cold rolled steel sheets to continuous roll welding lines. The joint interface feature has been greatly
improved by replacing the flash source with a laser source. In the early 2000s, two 45 kW CO2
lasers were applied to weld 30mm thick hot steel bars to continuous finishing rolling lines
(Minamida, 2002).
In the early 1980s, CO2 lasers were installed to make small diameter stainless steel welded
pipes to increase productivity, in this field of application, CO2 lasers are still used. For the
production of medium diameter pipes and heavy wall thickness, in the mid-1990s, a 25 kW CO2
laser source combined with high frequency induction coil preheating was applied (al H. e., 1996);
(al O. e., 2001).
2.6.4 Laser Welding in Shipbuilding Industry
The main requirements of welding technology suited for the shipbuilding industry are
maintaining the correct viscoelastic and mechanical properties of the weld metal, being able to
weld in the presence of gaps between edges of surfaces, and a maximum depth of welded seam.
Therefore, only high performing techniques can be used in the shipbuilding industry as they work
with heavy gauge metals. Research shows that a hybrid laser-arc welding technique will be most
suited to meet the criteria for this industry as it gives high quality welded joints, better productivity,
and higher production effectiveness. When compared to a simple laser welding technique, hybrid
laser-arc welding can give better conditions for alloy addition, heat adjustment and seam
formation, based on the thermal cycle calculations (Kristensen, 2009); (Levshakov, 2015).
2.6.5 Laser Welding in Medical Industry
As medical devices are becoming smaller and more precise, the requirements for better
welding technologies are also increasing. The medical devices need to be clean while being
environmentally friendly. Laser welding can provide micro grade weld with no effect on the
flexibility of the joint and the welding area, using nanosecond pulse laser and fiber laser welding

25
technology, making it suitable for use in medical industry. The features of laser welding over
conventional welding technologies used in the medical industry are the precise and reliable
operation and environmental protection and cleaning. Laser welding is becoming increasingly
demanded by the medical industry (Xie, 2013).
2.7 State of Technique
Laser welding has emerged as one of the most useful and advanced forms of welding
techniques (Acherjee, 2018). Substantial researches have already been executed in this field such
as one study emphasized on the keyhole behavior and weld ability in zero-gap laser welding of
zinc-coated steel sheets at very low atmospheric pressures (Kim, 2017).
In the experimentation process, an investigation was carried out to study the response of
the keyhole when the ambient pressure was decreased. In this method, for welding purposes, DP
590 steel sheets coated with zinc were used via coaxial observation. In comparison, the experiment
used both zinc coated and uncoated sheets. The uncoated sheets were used as control. For welding
purpose, a multi-mode fiber laser was used with 2kW intensity. In the process, a zero-gap lap weld
configuration was used. In order to test the welding efficiency, two energy density and four
different pressure variations were used. The energy density was kept at 1830W with 12.5mm/s and
1230W with 21.2mm/s. The pressure was successive increasing values of 0.1kPa, 1kPa, 10kPa and
101.3kPa. The study purposes analysis of both the top and bottom of the surfaces, a time averaged
keyhole was reconstructed. The keyhole had a three-dimensional configuration.
The experimental results showed that in the case of zinc-coated steel sheets, the
evaporation of zinc was significantly higher and much intense as compared to the steel evaporation
for the same pressures at sub-atmospheric levels. This caused the keyhole to fluctuate in the
direction of the welding and highly elongated. It was further observed that the bottom aperture
opening time was inversely proportional to the ambient pressure. This resulted from the
evaporation of the zinc coating on the steel sheet. It was followed by less energy absorption and
smaller melt pools were observed. Ultimately, the procedure showed poor weld quality and weld

26
chevrons spacing were not as narrow as required. On the contrary, welding process produced large
fumes and less emission of light (Kim et al., 2017).
In another study, the wetting and solidification characteristics of aluminum on zinccoated
steel in laser welding and braising was studied (Gatzen, Radel, Thomy, & Vollertsen, 2016). As
the construction industry is advancing, the metal structures are getting more sensitive and
lightweight (Gerhards, Reisgen, & Olschok, 2016). This calls for better and more accurate welding
processes. For this purpose, two types of laser welding processes are studied. One uses bead on
plate brazing and the other uses zinc coated steel and aluminum metal. The results showed that the
solidification and wetting characteristics were different in both cases. The single droplet model
that is useable for a bead on the plate cannot be used in overlap welding. The heat dissipation in
both cases was observed (Gatzen et al., 2016). In the straightforward model, the rate of the heat
loss by evaporations in bead and plate brazing was affected by the zinc evaporation. Similar was
the case in the droplet wetting. It was also found that in order to start the spreading on the metal
surface coated with zinc, the breaking of oxide layers is necessary. It is the only reason that
explains the divergent experimental results in comparison of both cases of bead on plate brazing
and single droplet wetting. The thickness of zinc also has a significant impact on the rate of
solidification. Zinc layers also act as a liquid bonding agent. It aids in better welding and
solidification (Jia et al., 2015).
In the automobile manufacturing units, the demand for lightweight manufacturing of
automobile units is in high demands. This calls for better technologies in the welding procedure
(Hong & Shin, 2017). A research was carried out that focuses on the laser overlap welding of zinc-
coated steel on aluminum alloy (Kashani, Kah, & Martikainen, 2015). For better strength and
durability of the structures of the automobiles, local reinforcement of the structure is carried out.
To decrease the overall weight of the structure, aluminum is used in most of its parts. For this
purpose, aluminum is reinforced with zinccoated steel by using patches welded by the laser beam.
This enhances the durability and strength of the automobile structure. In most of the cases, the
welding of the aluminum and zinc-coated steel is not durable and cracks in the structure are

27
frequent. The zinc, coated on the steel surface, evaporates rapidly during the welding process
(Reimann et al., 2017). As a result, the evaporation from the surface causes instability in the joints
of aluminum and steel at the junction point. It also destabilizes the pool and cavity. The
intermetallic compounds are brittle and cause weakness in the steel-aluminum structure. The
results show that higher strength can be achieved when the thickness of the intermetallic
compounds is kept at 10 micro-meters (Kashani et al., 2015). In addition to this, bonding, diffusion,
and orientation also play a significant role in strength of welding. Nitrogen gas when used in the
welding also improves the weld strength. In addition to this, the use of inert gases also enhances
the corrosion-resistant properties of the welding.
Lightweight automobile structures can help in better fuel economy and less emission of
greenhouse gases. Better welding can also increase the strength and durability of the structure
(Windmann, Röttger, Kügler, & Theisen, 2016). The study focuses on the effect of coating weight
on fiber laser welding of galvanized coated 22MnB5 press hardening steel (Razmpoosh, Macwan,
Biro, & Zhou, 2018). With the advancement in the fracture bearing capacity and elongation
properties, the crash performance has significantly been improved. For press hardening steel
tensile strength of 1.5 Giga Pascal as well as 8 percent elongation can be achieved. But the welding
press hardening steel has many challenges. The welding defects caused by coating mixtures can
lead to poor strength of the structure. The study finds that the effect of the Galvanneal coating
weight on the strength of the structure when used with the fiber laser welding (Razmpoosh et al.,
2018). Galvanneal coating has many impacts on the welding strength both in the process window
and welding geometry. As the amount of the coating is increased on the metal surface, the
penetration of the weld decrease that shows an inverse relation. With high coating weight the
amount of zinc on the surface increase. The welding of the zinc-coated metal results in more fumes.
Similarly, with the coating weight, fusion zone and heat-affected zone showed inverse proportion
in the welding process. It was also studied that here was no effect of the Galvanneal coating on the
tensile strength of the metal welded. EXD analysis also showed that the Galvanneal coating was
mixed with the weld pool. Increased coating pushes the process to the higher power of laser and
low speed of welding (Mei, Wang, Yan, Chen, & Xie, 2017).

28
In order to meet strength in automobile structure, advanced high strength steel is being
used (Sutar, Dharankar, & Raju, 2016). The strength of the structure also depends on the laser
welded joints. In the study, in addition to aluminum, silicon coating was also used. For the strength
analysis after dual Aluminium-Silicon coating, tensile, fatigue and Erichsen cupping test were
conducted (Sun et al., 2019). The results showed that ferrite and aluminum were present in the
fusion zone. Dominant martin sites were also present in the fusion zone. Large disorientations were
also present in both coated and non-coated metals. The tests showed that hardness in fusion zone
was more in the case of decoated metal as compared to the coated metal. The fatigue limit of the
coated metal was also less than the de-coated metal showing that coating decreases the strength of
the metal joints. In the case of the Erichsen tests, there was an insignificant difference in coated
and de-coated metals joints. But this effect was inverse in the case of ferrite on the Erichsen
cupping test.
2.9 COMSOL Multiphysics and Simulation
COMSOL Multiphysics is a program for multifunctional study of finite elements, resolver
and multiphysics. It supports user interfaces and couplings of partial differential equations (PDEs)
in traditional physicals. For electrical, mechanical, fluid, acoustic, and chemical applications,
COMSOL offers an IDE and coherent workflow.
Besides conventional problems, the main Multiphysics kit can be used to solve weak-form
PDEs with framework modules. The program can be managed externally through an API for Java
and Live Link for MATLAB and Autodesk Inventor. You may design individual custom domain-
sensitive simulation applications using an Application Designer. Users may use drag and drop
(Form Editor) or Method Editor (Method Editor) tools. COMSOL Server is a separate business
simulation program management software. COMSOL offers several modules which categories in
accordance with the Electrical, Mechanical and other engineering applications of field.
No COMSOL add-on products are needed for this simple illustration. Actually the Multiphysics.
See the more detailed model of structural dynamics model library of structural mechanics.

29
It is possible that you tensioned a bolt with a wrench at some stage in your life. The exercise takes
through a model for structural dynamics that analyses this simple activity, from the point of view
of the structural integrity of the loading wrist.
Naturally, the wrench is made of steel, a ductile material. The instrument would be permanently
deformed by the elastoplastic actions of the steel if the applied torque is too strong. To assess the
size of the clamping handle, verify if the mechanical stress level is below the yield stress.
The Model Wizard opens and introduces a physics option for robust dynamics. A geometry is then
imported and the material is stainless steel. You then investigate other key steps when constructing
a model, define a parameter and load boundary state, pick geometric entities in the Graphics
window, set the mesh and analysis and then numerically and visualize the output.
The tale has been regenerated and reveals the stress of von Mises Distribution under applied
vertical load in the bolt and wrench. For a standard stain for devices such as a wrench, the return
stress is around 600MPa, indicating that for our 150 N load (corresponding to about 34 pounds of
strength) we are moving closer to plastic deformation. You may also like a margin of protection
of, say, three. To rapidly determine which sections of the wrench are at risk of plastic deformation,
a word like solid.mises>200[MPa] is optimised for inequalities.

31
3.1 Flowchart
Figure 3.1 shows the flowchart of the experimental procedures taken.

32
Figure 3.1: Methodology flowchart
3.2 Material Preparation
Welding analysis should be performed before welding parts, including material selection,
joint design, placement tolerances, and required welding operations (Shannon,2016). The material
used for this study is Zincalume G550 steel.
3.2.1 Zincalume Steel
Figure 3.2: Cross section of Zincalume steel
By combining 1.5% Si, 55.0% Al, and 43.5% Zn the Zincalume coating is produced, that
offers high corrosion performance with a minimum coating mass of 150 g/m2 (AZ150). It has
better corrosion performance compared with other metal-coated steel under varying conditions. It
is manufactured by a continuous hot-dipped structural steel coated with zinc/aluminum alloy and
has a regular spangle surface. It gives strength of at least 550 MPa with limited ductility. It is good
for roll-forming with the smallest possible diameter of 4t. The Zincalume coating steel is used in
roofing, structural steel framing, and walling. Dasheet of Zincalume steel G500 is provided in
appendix B, refer for more information.
The Zincalume steel has high corrosion resisting performance due to the sacrificial
protection provided by zinc and the durable barrier provided by aluminum. In sacrificial protection,
a more active metal protects a less active metal by corroding in preference to the less active one.

33
Here zinc is the active metal while steel is the less active one. The zincalume steel has a complex
coating structure comprising of zinc-rich and aluminum- rich areas.
In this experiment six samples were welded. Table 3.1 shows the parameters selected for
this study, welding speed and laser power. Time taken to weld a one sample were also taken.
Table 3.1: parameters selected in the study
3.2.2 Safety Requirement
Lasers are associated with potential hazards such as laser light, power supplies, by-
products, etc., and require special care and protection for the processing of laser materials. Raffin
Starfire 300 is under 4 calcifications which has high eye and skin risks. The security alert is set as
a quartz security window during the installation process. A training in laser welding was supplied
before the machine is used and only authorized users can work with the machine. Warning signals
are installed both externally and internally of the lap. The fibers connected to the machine must be
at least 1 meter in diameter. The procedure for operating the system is always visible and is located
on the machine for easy search (P.Janasekaran, 2017).
Sample
Name
Laser Power
(w)
Welding Speed
(mm/s)
Processing Time (s)
1 225 20 23.34
2 235 18 25.92
3 245 18 25.92
4 235 16 29.14
5 225 16 29.13
6 245 16 29.14

34
3.3 Jigs and Fixtures
In order to hold different workpieces in a fixed position and alignment, special tools call
jigs and fixtures are used. They are used in industries that manufacturing industries during
machining operations. Jigs and fixtures are used interchangeably in the machining process and
keep the workpieces fixed at their positions to provide accuracy and repeatability. For laser
welding, a jig is used to hold the two surfaces in the correct position concerning the laser beam.
For a joint to be strong, the laser beam power and the jig force is crucial. Moreover, it is important
for reduced alteration, heat affected zone (HAZ), and dimensional changes (Ishak, 2012).
Figure 3.3: Jigs and Fixture (Ishak, 2012).
3.4 Cutting Prosses
To obtain the cross sections of the joining region, a linear precision saw with a diamond
cutter used to cut the molded samples. The machine is shown in Figure

35
Figure 3.4: Cutting machine (Model: Labotom-5, Struers)
3.5 Grinding Process
The cross section of the pair was grinded with a grinder (Fig. 3.5) to prepare sample for
microstructural properties evaluation. By rotating the grinding wheel at high speed, the grinder
produces flat, cylindrical and other surfaces. Grinding is a more accurate way to handle and finish
the parts. This machine has a type of: "surface grinding disc" for a flat surface grinding; and
"magnetic fixation MD-disc" to attach a magnetic polishing disc for polishing surfaces. More other
shaping forms can be shaped for different needs. In this study the three different grades of abrasive
paper were used for grinding the welded samples which they are respectively, 220, 1000 and 2000.
Then, the samples were refined utilizing MD-Mol cloth with the diamond suspension as shown in
figure3.5

36
Figure 3.5: Grinding machine (Model: LaboSystem, Struers)
3.6 Metallurgical Testing Setup
This section describes techniques for preparing materials to study metal profiles.
Configurations include cold mounting, cutting, grinding, polishing, and etching.
3.7 Digital Microscope
As shown in Figure 3.6, the side of the cross-section of the samples in this study was mainly
observed with a digital microscope (model: Dino-Lite, AM4515ZT, Taiwan). The Dino-Light
Edge series extends a wide range of microscopes to provide superior image quality and high
flexibility. All microscopes are equipped with a high-quality optical system, providing very bright,

37
bright, natural color images virtually without space and protection. Edge microscopes have a 20x
to a 220x magnification and are features of an automatic magnification mode with lockable focus
dial to aid in the measurement function. (Carter & & Shieh, 2015); (Komvopoulos, 2010).
Figure 3.6: Digital Microscope (Carter & & Shieh, 2015)
3.8 Scanning Electron Microscopy
SEM is used to study the surface of a specimen in detail. In this process, a powerful electron
beam is used to scan the surface of the specimen, which is normally gold or platinum-coated,
providing a better SNR and improved contrast. The electron beam hits the surface of the specimen
and generates different signals as it interacts with it. These signals can be emitted near or at the
specimen surface. The signals are picked up and processed and eventually displayed as the surface
topography of the specimen. The image thus formed is 3D as shown in figure 3.16. Mainly, low
energy secondary electron signals are collected from the surface. The high energy electrons and

38
X-rays emitted by the internal layers of the specimen are used to collect information about the
composition of the specimen (P.Janasekaran, 2017).
Figure 3.7: Scanning Electron Microscopy (P.Janasekaran, 2017).

39
CHAPTER 4
NUMERICAL ANALYSIS AND SIMULATION

40
4.1 Numerical Analysis
In order to fulfil environmental issues, the demand for low weight cars pushes the automobile
industry to weight reduction, while maintaining the structural integrity and crash dignity of the car.
In the automotive industry, the value of lightweight materials has also increased in their
construction. As a result, lightweight materials such as zincalume, magnesium and high strength
stainless steel are found in conventional materials such as cast iron or low carbons stains.
Advanced AHSS and aluminum alloys, owing to their high strength to weight ratios that improve
car performance, are used mainly in automotive bodies. Laser beam soldering is one of the leading
techniques to link steel and alloys than traditional welding methods as it is a high density energy
process that prevents the production of brittle intermetallic by high heating and cooling speeds in
laser welding. Different material laser welding is often used in Tailor Welded Blanks (TWB)
where single or multiple thickness sheets and components are sold together prior to shape.
However, joining alloys to steel causes many problems such as fragrant inter-metal shape, low
steel weathering to alloy owing to its low miscibility during welding. Because of their widespread
thermal properties (660 ° C, alloys, steels 1560 ° C, thermal expansion and conductivity, for
example) melting temperatures, various thermal expansion. To understand the physical
phenomena behind the process of welding. The geometry of the weld bead (sweat width and
welding depth) must be predicted by constructing a model. The final shape of the weld pool can
be predicted by a thermal transfer and fluid flow model. The high energy laser beam raises the
material 's temperature above its point of fusion and even beyond the point of boiling. A process
called Marangoni convection arises due to wide temperature gradients at the surface of the sold
pond. The convection of Marangoni influences the weld shape. Many experiments were performed
for simulating the method of laser welding. In the keyhole soldering of dense Zincalume sheets, a
modelled effect of a permanent state magnetic field. As a consequence of the use of steady
magnetic field, a Lorentz braking force dependent on Hartmann effect has created major variations
in the flow pattern of the solder pool and the temperature distribution. The marangoni convection
is diminished by the induced magnetic field. Two dimensional (2D) model of axial symmetry was
developed by Courtois et al. to research during welding the related physical phenomena for the
creation of defects. The process stage range was implemented in the model and a phase transition
was simulated in this way from liquid to vapor. A study was also made of the interactions of steam
jet and fluid surface. In order to predict the deformed solder profile and the 2D-Hydro Dynamics
model, Guen et al. Developed a 3D thermal architecture for simulating fluid flow across the bolt.
In the current work, the laser soldering model of material specimen is formed as three dimensional
(3D) axial symmetry in conductive welding mode. The purpose is to evaluate the solid-liquid
interface, the deformed welded pool shape and the surface tension forces of Marangoni. To verify
the specification, tests on dual phase steel and zinc alloy in conduction mode are performed using
a high-power diode laser. Both the heat transfer and the flow model are taken into account in the
model. In relation to the experimental findings for prospective work the temperature distribution
of the welding ponds and welded pool geometry should be performed.

41
4.2 Mathematical Formulation
The laser parameters differ by the laser beam energy density measured with Eq1. Laser criteria
used in Table 1. Table 1 for tests and modelling.
Laser energy density (LED) =
Laser power area
Unit
× (
Laser beam diameter
(Scanning speed )
)
LED = 4P/ πD^2 × D/V (1)
Whereas,
P is the laser power (kW),
D is the laser beam diameter (mm),
and V is the laser beam scan velocity (mm /s).
In order to understand the dependency of the flow pattern and surface tension gradient on a melt
pool form on the weld, a 3D computational model was developed. The computer model integrating
multiphysics effects (heat transfer and laminar fluid flow) to predict the temperature background
of the molten pool, the cooling rate and the flow of fluid. The energy conservation equations (Eq.2)
impetus (Eq.3) and mass (Eq.4) are solved for heat transfer and fluid flow simulation. The models
contain the following assumptions.
1. Fluid metal is known as Newtonians under flow as incompressible.
2. Heat origins from Gaussian.
3. Approximation Boussinesq true
Where ρ is of density (Kg / m3), Cp is the material specific heat (J / Kg. K), u is the molten metal
velocity and T is the temperature absolute. Eq gives the original condition. 3 where T0 is held at
the original temperature at 293 K.
𝑇 (𝑥, 𝑦, 𝑧, 0) = 𝑇0 (3)
The entire geometry except the lower surface was assigned to the convective cooling and the
environmental radiation limits as seen in the diagram. 2 and the geometry bottom has been given
thermal insulation. Eq.4 expresses the boundary conditions and heat flow.

42
Figure 3.8: Schematic of laser welding process
The model utilizes a Gaussian distribution of the heat source and the energy density specified in
Eq. 5 to the limit 6 in the fig. Fig. 2. Of Equality. 2 In the source word laser strength is not specified
and thus specified in the thermal transport module as a separate limiting condition as heat flux (Eq.
5).
In order to assess the deflection of the welding pool under different boundary conditions such as
convection of the Marangoni, force gravitation and surface tension forces the thermal transfer
model has been introduced into fluid stream Multiphysics. For fluid flow in the sold the fluid
equations of mass (Eq.6) and momentum (Navier-Stokes, Eq.7) were used.
Where F is the volume force (N), g is the gravity acceleration, α is the thermal expansion
coefficient (1 / K) and Tm is the moulting temperature.

43
Owing to the surface tension of the soldering pool, the marangoni convection is a fluid flow. The
convection of Marangoni on the top surface is allocated to border 6.
The surface tension temperature derives from μ where dynamic viscosity (Pa-s) and μ are found.
The properties of the material. Relevant heat and thermal conductivity temperature-dependent and
the specifications for laser processing are summarized in the table. 2, table. 2, table. 3 and table. 3
and table. 4.
Table 3.2: Temperature dependentthermal propertiesof zincalume 550
Property 𝐍𝐨𝐦𝐞𝐧𝐜𝐥𝐚𝐭𝐮𝐫𝐞 𝐕𝐚𝐥𝐮𝐞𝐬
Density 𝜌 7594[𝑘𝑔/𝑚3
Temperature
derivative of surface
tension
ᵧ −3.5𝑒 − 4 [𝑁/(𝑚. 𝐾)]
Thermal expansion
coefficient
𝛼 2.7𝑒 − 5[1/𝐾]
Dynamic viscosity µ 1.15 [(𝑚 ∗ 𝑃𝑎)/𝑠]
Convection
coefficient
𝛹 2975 [𝑊/𝑚2 ∗ 𝐾]
Emissivity 𝐸 0.1
4.3 Modeling and Meshing
Figure 3.9 indicates the axis of the model. The geometry and load symmetry is used to model just
half of the two soldered surfaces. To save measurement costs, a non-uniform finite element mesh
(FE) is used. As shown in Fig 3.9, part 1 uses a dense mesh to have good numerical accurateness,
part 3 uses a much grosser mesh, and part 2 is used for linking the other two sections. Part 1 is
meshed by a hexahedral portion with 20 nodes, Part 2 is tetrahedral with 10 nodes and Part 3 is
tetrahedral with 8 nodes. As in the figure. The FE mesh uses the same mesh density as in the
adjacent material region to take into consideration a zinc coating at the faying surface. Zinc coating
thickness is set in the FE model at 0.025 mm on steel surfaces.
A COMSOL based subroutine is written to simulate the melting and vaporizing areas of the metal
and zinc coating at the faying surface of two steel sheets respectively. Fig 3.11 shows the
temperature distribution in the FE model and along the faying surface acquired from the simulation
results. From the temperature distribution profile, the isotherms that corresponds of the boiling
point (2800 C) and the melting point (1500 C) of the DP980 steel denote the keyhole and the

44
melted steel boundary, while the region between the isotherms that represent the zinc boiling point
(907 C) and the steel melting point indicates the vaporized zinc zone.
The independence of the grid is essential to the accuracy of numerical simulation, but is commonly
overlooked, according to Gross' work presented in Dowden's book. Several mesh levels are
selected in this analysis to verify the impact of mesh size on convergence of calculations (element
numbers ranging from 10,000 to 70,000 in the scales of distance, length and depth). A parametric
analysis of mesh convergence is conducted. As in the Fig 3.10. After 45,000 components,
simulated temperature data become autonomous in the mesh density. Therefore, this analysis
selects a mesh of over 55,000 elements. The elements on the top and bottom sheets near and around
the welding line are 0.2 mm 0.1 mm; zinc-coating elements on the felling surface are 0.3 mm 0.2
mm 0.05 mm. The method of simulation is seen in the Fig. 3.11. The first is to take into account
zinc coating for a computer-assisted design (CAD) model of galvanized steel sheets in a zero-gap
lap joints. Zinc is density 7140 kg / m3 and its density is 7842 kg / m3 thermal conductivity, k
and specific heat power, 𝑐𝑝, depend on the temperature of Yang's dissolution and of the American
Galvanizers Associations shown in the figure. Provided that the welding area is situated at a high
temperature gradient, a finer mesh is selected near and within the solder area. Then the thermal
boundary conditions, and the rotary Gaussian volumetric heat source model, are defined to
simulate the temperature profiles. Based on the simulation results, the area of the zinc boiling zone
versus the molten pool area can be acquired.
For boundary 6 along the melting zone a free tetrahedral mesh was created, with a maximum
element size of 15 μm and a minimum of 0,6 μm. In the other domains where the effect of the heat
source is minimal, a very fine mesh was developed. In order to analyze the minute temperature
difference in the soldering process the computer model was resolved in small steps (0.1s). Point
domain samples have been positioned from top to bottom as a cross-section to monitor temperature
change in each phase.
Figure 3.9: 3D CAD model of welding surface of zincalume 550

45
Table 3.3: Welding parameters selected
Figure 3.10: Mesh parameter set for 100mm x 100mm x 20mm
Sample Name Laser Power (w) Welding Speed (mm/s) Processing Time (s)
1 225 20 23.34
2 235 18 25.92
3 245 18 25.92
4 235 16 29.14
5 225 16 29.13
6 245 16 29.14

46
4.4 Results and Discussion
The effects of a moving laser beam on the end form of the weld were produced in a 3D model (Fig.
3). The rise and decrease by Marangoni's convection and surface tension forces in the melted pond
with higher Laser Intensities, convection and radiation losses as well as the flow of water
substantially affects the morphology of the weld bead. In contrast to the sides, a Gaussian laser
beam creates high energy in the middle resulting in non-uniform welding type with maximum
penetration distance in the center of the beam.
Figure 3.11: Three dimensional view of laser beam welding process.
In the creation of the welding bead laser energy density (LED) plays a key role. The model shows
that the maximum temperature raises as the LED grows. The increase in temperatures leads to
higher penetration depths as the amount of heat in the material increases. The models developed a
solder width of 6400 μm and a depth of 789 μm with an LED of 371 J / mm2 (Figure 3.11). The
sole width and penetration depth at a lower LED of 297 J / mm2 decreased to the figure of 5410
μm and 393 μm. 5. The temperature profile has been derived from border 6 using the domain point
samples (Fig 3.11), which were placed in the YZ plane along the cross section of the soil. The
temperature profile for both cases with LED (371 J / mm2 and 297 J / mm2) represents the heating
time and the cooling time in Fig. 3.12 and 3.13. The laser stays in contact with the substrate for a
longer time with a higher LED (371 J / mm2, i.e. at lower scan speed (8 mm / s) and raises the
temperature of the laser to around 0,4 s (8200 km). The heating time decreased as the LEDs
decreased to 297 J / mm2 and the peak temperature decreased to 0.25 s by ~7.800 K. The

47
Marangoni convection forces are another significant phenomena regulating the width and depth of
the solder. The result of marangoni is the transfer of mass due to the gradient of the shaped welding
bowl's surface tension.
Figure3.12: Plot probe of temperature at XY plane for all time
Laser power: 225 W for time t=2 sec
3.13: Plot of probe point temperature along the YZ plane

48
Figure 3.14: Effect of Marangoni convection in the weld pool due to difference in temperature gradient
Table 3.3: Welding parameters selected and extracted temperature
Through the increase in temperature, the surface tension of the molten metal increases. A lower
surface tension is added to 'a' of the colder liquid and pulled to 'b' (Figure 3.14). An additional
shear pressure is induced by the surface tension gradient along the melted pond [Carter & & Shieh,
2015]. This allows the molten metal to travel from the middle of the soot to the sides of the pool
and revert to the surface of the pool as seen in the figure. 8. At higher LEDs, the convection of
Marangoni increases and thus increases the diameter of solder. Compared to the marangoni
convection forces in the solder, the effect of surface tense and gravitational forces was negligible.
Sample Name Laser Power (w) Welding Speed (mm/s) Processing Time (s) Temperature (k)
1 225 20 23.34 510
2 235 18 25.92 575
3 245 18 25.92 601
4 235 16 29.14 623
5 225 16 29.13 655
6 245 16 29.14 688

49
Figure 3.15: Temperature contour on moving welding beam at t=2sec
A highly pressurized zinc vapor is produced around the molten pool by the zinc boiling point
isotherm (907 C). The zin vapor does not have the means to exit, it reaches into the fluid phase
region of the shaped tub, which results in spreads and blowholes, as galvanized steel was welded
in a zero-gap lap joint configuration. The surface area (a) laser energy during solidification is 225
W (b) Laser capacity: 235 W (c) Laser capacity: 245 W. DP980 galvanized coupons with different
laser power (sweating speed is set at 10 mm / s) micrographs of the fracture portion of sold. Fig.-
Fig. 3.15. DP980 galvanized coupons for tensile sharpness testing (welding speed 10 mm / s is
determined), the failure load versus laser ability. (a) Speed for soldering 5 mm / s (b) Speed for
soldering 20 mm / s (c) Speed 18 mm / s (d) Speed for soldering 18 mm / s (Table 3.3). Twenty.
At the cell surface with varying soldering speeds (laser strength 235 W) the vaporized zinc region
vs. steel was melted. J. The voltage of liquid steel rises and blow-holes cannot be closed (Ma et
al). Structures and architecture of weld can be seen under various soldering parameters, the
complex behavior of the large and small molten weld pool at different periods is acquired. Since
zinc vapors are produced readily and the escape from the molten swimming pool, the size of the
molten pool fluctuates significantly and the bottles are created. The expanded molten pool is
though and required more stability. More stability, as stated earlier, there is a longer solidification
period for the expanded solder pad that will make zinc steam easier to escape. In the other hand,
though, a greater sold pool means that the region of boiling zinc is expanded. The further spray
and blowholes are created by the greater quantities of vaporized zinc escaping through a sold pond.
The consistency of the weld is influenced by both the amount of zinc vapor that escapes from the

50
molten pool and the size of the molten pool. Therefore, the characteristic parameter k of the zinc
vapor flow through the molten material at the surface of the fray is explained in this analysis. The
characteristic parameter (k) may be represented by the ratio from the zinc coated vaporised area
(𝐴𝑧𝑖𝑛𝑐) to the molten pond area of the dropped base, assuming a constant zinc coating thickness:
𝑘 1 ⁄ 4 𝐴𝑧𝑖𝑛𝑐 = 𝐴𝑚𝑒𝑙𝑡 ∗ 𝐴𝑑𝑎 The larger the k is, the greater the zinc steam that flows through
the pond and the easier it is to produce spreads and blowholes. The numerically acquired k value
can then be used to approximate solder efficiency in relation to various parameters of laser
welding. In order to investigate the relationship between k and the weld quality, two simulations
are carried out Two simulations are carried out to analyses the interaction between k and solder
efficiency. In one case, the effect of laser force on the k was investigated and in the other case, the
effect of welding speed on the k was investigated. The simulations for all these scenarios was
carried out with the same laser power and soldering speed as those used to evaluate the simulation.
The first selection process is for 235 W, 225 W, 245 W and the soldering speed is fixed at 20 mm
/ s, respectively. Fig. 3.13 displays the vaporized zinc-coated region and the area of the steel weld
tank, as mentioned above. As a result of increased laser intensity, both areas will increase but have
different increases and the characteristic parameter (k) will decrease. It means that as the absolute
amount of vaporized zinc increases, with the increase in laser intensity it reduces the amount of
the zinc vapor that escapes from the molten pool at the disappearing surface. Simultaneously, the
experimental data suggest that the porosity of welds decreases and that, with the rise of laser
strength, the volume of the zinc vapor that leaked from the molten pool decreases in the fallen
surface. During the welding process less vapor was trapped in the molten tank. Thus, with laser
power improvement, the surface strength of the weld increases. The related tensile shear testing
findings indicate that the inner pores of the fracture section decrease and the soldering joint failure
load increases. With a continuously sustained solder rate (20 mm / s), the efficiency of the solder
is increased by increasing the laser strength. In the second case, 18 mm / s, 16 mm / s is chosen
and the laser output of 235 W is set. Indicates that the region of boiling zinc and the molten pool
decreases at different rate of change with an improvement in welding rate. The improvement in
these areas is linearly related to the soldering speed. As a consequence, with an increase in the
soldering rate, the parameter (k) increases, which implies the volume of zinc vapor escape by the
disappearing surface by the molten cup. The surface-quality of sold at a constant laser power at
varying welding speeds shows that the soldering speed of 16 mm / s is appropriate. Since the
welding pool formed at this comparatively low (approximately 16 mm / s) welding speed is greater
and provides more solidification time to escape the zinc vapor. There is clearly a reduction in the
likelihood that the zinc vapor is stuck in the molten pool. In addition, the internal pores rise in laser
power at a steady rate of welding can be seen from the fracture section. The findings of the tensile
shear test of the welds at constant laser power at varying solder speeds imply that the sheer force
of the DP980 solder joint will increase when the soldering speed fall. According to Karlsson and
Kaplan reports, however, when the welding speed is incredibly poor, it is possible to produce
another form of weld defect such as slinging, which should also be avoided during the welding
process.

51
Conclusions
The present paper discusses the initial effects of laser welding of various materials. The effects on the form
of the weld bead (weld width / weld depth) were tested both numerically and experimentally for laser
parameters such as laser strength, scanning speed and laser beam diameter. A study has also been carried
out of the results of convection, gravitational forces and surface tension forces for the molded weld. The
solid-liquid interface of the weld was shown to be primarily controlled by the Marangoni forces. There
have been less extreme effects of gravity and the surface tension than the Marangoni convection. With a
greater temperature differential in the welded tube, the Marangoni convection appears to increase the
soldering width at a lesser scanning speeds. The estimation results demonstrated strong qualitative
consistency with the related experimental values. The minor difference in depth and width of the
penetration. This could happen when a difference in the laser absorption values with a rise in temperature,
speed and time was not taken into consideration.

52
REFERENCES
Acherjee, B. (2018). Hybrid laser arc welding: State-of-art review. Optics and Laser Technology,
99, 60–71.
Aitzol, L., Eneko, u., Ivan, T., & silvia, M. (2011). Thermal advanced machining processes. In J.
Paulo Davim, Modern Machining Technology (p. 412). UK: Woodhead Publishing.
Amo, J., Duran, J., Chao, J., & Fernandez-Saez, J. (1996). Laser welding of Al55–Zn coated
steel sheet. J Mater, Sci 31, 6595–6607.
Bansal, V., Singh, S., & Singh, S. (2016). Study of laser beam welding. Trends in Welding and
Manufacturing Research, Sant Longowal Institute of Engineering and Technology.
Carter, M., & & Shieh, J. (2015). Guide to Research Techniques in Neuroscience. In M. Carter,
& J. & Shieh, Microscopy (pp. 117-144). United States: Elsevier Science Publishing.
Chen, H.-C. (2010). Fibre Laser Welding of Dissimilar Materials. Manchester: University of
Manchester.
Corba, C., ferencz, P., & Mihaila, I. (2018). Laser welding. Nonconventional Technologies
Review, 34-37.

53
Czerwinski, F. (2011). Magnesium Alloys Design, Processing and Properties. In F. Czerwinski,
Magnesium Alloys: Design, Processing and Properties (pp. 469-486). Canada : In tech.
Deyong, Y., Xiangdong, G., & Katayama, S. (2014). Multisensor Fusion System for Monitoring
High-power Disk Laser Welding Using Support Vector Machine. Vector Machine, 1-10.
Ewing, J. (2018). Excimer Lasers. Encyclopedia of Modern Optics, 358-367.
Fernandes, F., Oliveira, D., & Pereira, A. (2017). Optimal parameters for laser welding of
advanced high-strength steels used in the automotive industry. Procedia manufacturing, 219-226.
Gatzen, M., Radel, T., Thomy, C., & Vollertsen, F. (2016). Wetting and solidification
characteristics of aluminium on zinc coated steel in laser welding and brazing. Journal of
Materials Processing Technology, 238, 352–360.
Gerhards, B., Reisgen, U., & Olschok, S. (2016). Laser beam welding of ultrahigh strength
martensitic steels with active cooling. Journal of Laser Applications, 28(2), 022408.
Grigoryants, A., & Grezev, V. (2015). Special features of laser welding using fibre and CO2
lasers. Welding International, 1-6.
Hong, K.-M., & shin, Y. (2017). Prospects of laser welding technology in the automotive
industry: A review. Journal of Materials Processing Technology, 245, 46-69.

54
Ishak, M. (2012). Design And Fabrication of Jig For Butt Welding. Malaysia: Universiti
Malaysia Pahang.
Jia, L., Shichun, J., Yan, S., Cong, N., Junke, C., & Genzhe, H. (2015). Effects of zinc on the laser
welding of an aluminum alloy and galvanized steel. Journal of Materials Processing Technology,
224, 49–59.
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