ROTARY FRICTION WELDING BY CONVENTIONAL LATHE - MTECH PROJECT.pdf

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EVALUATION OF MECHANICAL AND
METALLURGICAL PROPERTIES
OF METALS JOINED BY
ROTARY FRICTION WELDING
WITH CONVENTIONAL LATHE
Dissertation submitted in partial fulfillment of
the requirements of the degree of
MASTER OF TECHNOLOGY
by
SURESH BABU E.M.
(Reg. No. 15314013)
Project guide:
Dr. K.P.S. NAIR
Reader in Mechanical Engineering (Retired)
DIVISION OF MECHANICAL ENGINEERING
SCHOOL OF ENGINEERING
COCHIN UNIVERSITY OF SCIENCE AND TECHNOLOGY
September 2016

i
DISSERTATION APPROVAL
This dissertation entitled “Evaluation of mechanical and metallurgical properties
of metals joined by rotary friction welding with conventional lathe” by
Suresh Babu E.M. is recommended for the award of the degree of Master of Technology.
Members of the Examination Committee
(Name & signature)
……………………………………… ……………………………………..
……………………………………… ……………………………………..
……………………………………… ……………………………………..
……………………………………… ……………………………………..
…………………………………….... ……………………………………..
Date: ………………………………..
Place: ……………………………….

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SCHOOL OF ENGINEERING
COCHIN UNIVERSITY OF SCIENCE AND TECHNOLOGY
C
CE
ER
RT
TI
IF
FI
IC
CA
AT
TE
E
This is to certify that the dissertation work entitled “Evaluation of mechanical and
metallurgical properties of metals joined by rotary friction welding with conventional
lathe” is a bonafide record of work carried by Mr. Suresh Babu E.M., Reg. No. 15314013,
submitted to the Department of Mechanical Engineering, School of Engineering, in partial
fulfillment of the requirements for the award of the degree of Master of Technology in
Mechanical Engineering at Cochin University of Science and Technology, Kochi during the
academic year 2016-2017.
Guided by:
Date: ……………………..
Guided by:
……………………………………………..
Dr. K.P.S. Nair,
Reader in Mechanical Engineering (Retired),
Division of Mechanical Engineering,
School of Engineering, CUSAT
Kochi- 682 022
Head of the division:
……………………………………………
Dr. Biju N.
Associate Professor and Head of Division
Division of Mechanical Engineering
School of Engineering, CUSAT
Kochi – 682 022

iii
DECLARATION
I declare that this written submission represents my ideas in my own words and where others'
ideas or words have been included, I have adequately cited and referenced the original
sources. I also declare that I have adhered to all principles of academic honesty and integrity
and have not misrepresented or fabricated or falsified any idea/data/fact/source in my
submission. I understand that any violation of the above will be cause for disciplinary action
by the University and can also evoke penal action from the sources which have thus not been
properly cited or from whom proper permission has not been taken when needed.
…..…………………..
Suresh Babu E.M.
(Reg. No. 15314013)
Date: 20/09/2016

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ACKNOWLEDGEMENT
This dissertation entitled “Evaluation of mechanical and metallurgical properties of
metals joined by rotary friction welding with conventional lathe” is one of the most
significant accomplishments in my life and it would be impossible without people who
supported me and believed in me.
To begin with, I express my deepest regards, unbound gratitude with sincere thanks to my
guide respected Dr. K.P.S. Nair, Reader in Division of Mechanical Engineering (Retired),
School of Engineering, Cochin University of Science and Technology for his valuable
guidance.
I would like to express my sincere thanks to Dr. Biju N., Head of Division & Associate
Professor in Mechanical Engineering, School of Engineering, Cochin University of Science
and Technology for all his assistance.
I take this opportunity to express my heartfelt gratitude to the respected Prof. Joseph
Alexander, Course Co-ordinator & Professor in Division of Mechanical Engineering, School
of Engineering, Cochin University of Science and Technology for his valuable advice,
suggestions and encouragement during the course of my work.
I extend my sincere thanks to Dr. Sreejith P.S., Professor in Division of Mechanical
Engineering, School of Engineering & Dean-faculty Engineering, Cochin University of
Science and Technology for his valuable teaching, guidance and support.
I also thanks to all faculties in Division of Mechanical Engineering, School of Engineering,
for their valuable support.
I would like to express my sincere thanks to all my friends and subordinate staffs working
with me, who are supporting to do my project work.
Last of all, I would like to express my heartfelt gratitude to my wife who inspired me in
making this endeavor a success.
Suresh Babu E.M.

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ABSTRACT
Friction welding is a solid state welding process in which two work pieces are joined under a
pressure providing an intimate contact between them and at a temperature essentially below
the melting point of the parent material. This type of welding is extensively used in the
industries like aerospace, automobile, agricultural, construction, oil & gas, military,
pharmaceuticals, etc., because the welds are of forged quality, with a 100% butt joint weld
throughout the contact area. This creates a bond strong enough to handle the high stress and
torque required of heavy machinery components including hydraulic piston rods, rear axles,
gears, etc.
In order to conduct the rotary friction welding, Hindustan Machine Tools Limited make
NH22 model conventional lathe was used. As this machine has large number of inbuilt speed
variations, can easily change over to the required spindle speed of 1210 RPM and 2040 RPM
during the friction welding.
There are seven combinations of similar and dissimilar metals are used for friction welding.
Carbon Steel (20C15), Stainless Steel (SS304), Copper (C10300) and Aluminium Alloy
(6063) are the base metals used for friction welding and the work has done in lathe with two
spindle speed of 1210 RPM and 2040 RPM. For conducting tensile test, Rockwell hardness
test and microscopic evaluation, three sets of joints were made.
After the experiment, one set sample was used for tensile test, one set was used for hardness
test and remaining one set sample was used for microscopic evaluation test (SEM test).
The results of the preliminary studies were used for the main set of experiments in the current
work. Tensile test, hardness test were conducted. The microstructural features of the weld
and parent metal has been studied and correlations with mechanical properties have been
done. SEM test has been carried out to study the effect of friction welding parameters on
nature and type of fracture. A correlation between friction welding parameters and type and
nature of fracture has been seen in this study.

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TABLE OF CONTENTS
Title Page No.
Dissertation Approval i
Certificate ii
Declaration iii
Acknowledgement iv
Abstract v
List of figures ix
List of tables xi
Abbreviations and notation xiii
Chapter 1 - Introduction to friction welding (1-7)
1.1 Friction welding 1
1.2 Rotary friction welding 1
1.2.1 Continuous drive friction welding 2
1.2.2 Stored energy friction welding 3
1.2.3 Combined (hybrid) friction welding 3
1.3 Other friction welding techniques 3
1.3.1 Radial friction welding 3
1.3.2 Friction stud welding 3
1.3.3 Friction surfacing 3
1.3.4 Friction taper plug welding 3
1.3.5 Friction taper stitch welding 4
1.3.6 Friction stir welding 4
1.3.7 Friction seam welding 4
1.3.8 Friction lap seam welding 4
1.3.9 Friction plunge welding 4
1.3.10 Friction co-extrusion cladding 4
1.3.11 Friction hydro-pillar processing 4
1.3.12 Linear friction welding 4
1.3.13 Thermo plastic friction welding 5
1.4 Basic principle of friction welding 5
1.5 Advantages of friction welding 6
1.6 Disadvantages of friction welding 6
1.7 Limitation of friction welding 7
1.8 Objectives of the work 7
Chapter 2 – Literature review (8-27)
2.1 Introduction 8
2.2 Fact and findings 8
2.3 What is friction welding? 8
2.4 Why friction welding? 8
2.5 Theory of friction welding 9

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TABLE OF CONTENTS ..Contd.
2.6 History of the friction welding 9
2.6.1 Historical developments in friction welding 10
2.7 Research work on friction welding 11
2.8 Material combination weldable by friction welding 15
2.9 Friction welded components and their application 16
2.9.1 Aerospace industry 16
2.9.2 Agriculture/ Construction industry 17
2.9.3 Automotive industry 18
2.9.4 Oil and Gas industry 19
2.9.5 Military 20
2.10 Variable and parameters that govern the quality of the welded
components 21
2.11 Plot welding parameter verses time in continuous drive friction
welding 22
2.12 Characteristics of friction welded components 23
Chapter 3 – Experimental work (28-45)
3.1 Introduction 28
3.2 Material selection 28
3.3 Specification, properties & application of rotary friction welding 29
3.3.1 Carbon Steel (20C15) 29
3.3.2 Stainless Steel (SS 304) 30
3.3.3 Copper (C 10300) 31
3.3.4 Aluminium Alloy (6063) 32
3.4 Experimental setup 33
3.5 Experimental procedure of rotary friction welding 35
3.5.1 Work-piece preparation 36
3.5.2 Work-piece setting 36
3.5.3 Operational steps in welding 36
3.5.4 Data measurements 38
3.5.5 Testing & Analysis 38
3.6 Observations 45
Chapter 4 – Results & discussions (46-74)
4.1 Carbon Steel (20C15) – Carbon Steel (20C15) 46
4.1.1 Results & findings 46
4.1.2 Tensile test results 47
4.1.3 Rockwell hardness test 48
4.1.4 Microscopic evaluation test (SEM test) 49
4.2 Carbon Steel (20C15) – Stainless Steel (SS 304) 50

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TABLE OF CONTENTS ..Contd.
4.3 Carbon Steel (20C15) – Copper (C 10300) 55
4.4 Carbon Steel (20C15) – Aluminium Alloy (6063) 59
4.5 Stainless Steel (SS 304) – Stainless Steel (SS 304) 63
4.6 Copper (C 10300) – Copper (C 10300) 67
4.7 Aluminium Alloy (6063) – Aluminium Alloy (6063) 71
Chapter 5 – Summary and conclusion (75-77)
References (78-79)

ix
LIST OF FIGURES
Fig.No. Caption Page
1.1 Basic principle of friction welding 5
2.1 Material combination weldable by friction welding 15
2.2 Friction welded components and their application in Aerospace industry 16
2.3 Friction welded components and their application in Agriculture industry 17
2.4 Friction welded components and their application in Automotive industry 18
2.5 Friction welded components and their application in Oil & Gas industry 19
2.6 Friction welded components and their application in Military industry 20
2.7 Generalized plot of welding parameters verses time in friction welding 22
3.1 Carbon steel (20C15) work pieces 29
3.2 Stainless Steel (SS 304) work pieces 30
3.3 Copper (C 10300) work pieces 31
3.4 Aluminium Alloy (6063) work pieces 32
3.5 Experimental setup 33
3.6 Interface temperature measurement with infrared thermometer 33
3.7 Forge force measurement with hydraulic pressure gauge 33
3.8 Tailstock attachment 33
3.9 NH 22 lathe used for rotary friction welding (before fixing attachment) 34
3.10 100mm length work pieces for friction welding (for hardness test) 35
3.11 Pre-contact 36
3.12 First friction 36
3.13 Second friction 37
3.14 Forge 37
3.15 Weld complete 37
3.16 Flash removal 37
3.17 Tension test on 30T Universal Testing Machine 38
3.18 Friction welded component for tension test 39
3.19 Hardness testing techniques 40
3.20 Friction welded component for hardness test 41
3.21 Rockwell hardness testing 41
3.22 Sample preparation for microscopic evaluation (SEM test) 42
3.23 Etching process 43
3.24 Polished samples for microscopic evaluation test 43
3.25 SEM test arrangements 44

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LIST OF FIGURES contd.
Fig.No. Caption Page
4.1 Rotary friction welded joint – Carbon Steel – Carbon Steel 46
4.2 Micrographs of friction welded components (Carbon Steel-Carbon Steel) 49
4.3. Rotary friction welded joint – Carbon Steel – Stainless Steel 51
4.4 Micrographs of friction welded components (Carbon Steel-Stainless Steel) 54
4.5 Rotary friction welded joint – Carbon Steel – Copper 55
4.6 Micrographs of friction welded components (Carbon Steel-Copper) 58
4.7 Rotary friction welded joint – Carbon Steel – Aluminium alloy 60
4.8 Rotary friction welded joint – Stainless Steel – Stainless Steel 63
4.9 Micrographs of friction welded components (Stainless Steel-S. Steel) 66
4.10 Rotary friction welded joint – Copper – Copper 67
4.11 Micrographs of friction welded components (Copper-Copper) 68
4.12 Rotary friction welded joint – Aluminium Alloy – Aluminium Alloy 71
4.13 Micrographs of friction welded components (Aluminium-Aluminium) 74

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LIST OF TABLES
Table
No .
Caption Page
2.1 Historical developments in friction welding 10
2.2 Recent research work in friction welding 11
2.3 Variables and parameters govern the quality of the friction weld 21
2.4 Characteristics of friction welded components 23
3.1 Material composition of Carbon Steel 29
3.2 Material composition of Stainless Steel 30
3.3 Material composition of Copper 31
3.4 Material composition of Aluminium 32
3.5 Common Rockwell hardness scales 41
3.6 Observations of rotary friction welding 45
4.1.1
Measurements of parameters controlling the friction weld quality
(Carbon Steel – Carbon Steel)
47
4.1.2 Tensile test results (Carbon Steel – Carbon Steel) 47
4.1.3 Rockwell hardness test results (Carbon Steel – Carbon Steel) 48
4.2.1
(Carbon Steel – Stainless Steel)
51
4.2.2 Tensile test results (Carbon Steel – Stainless Steel) 52
4.2.3 Rockwell hardness test results (Carbon Steel – Stainless Steel) 53
4.3.1
(Carbon Steel – Copper)
56
4.3.2 Tensile test results (Carbon Steel – Copper) 56
4.3.3 Rockwell hardness test results (Carbon Steel – Copper) 57
4.4.1
(Carbon Steel – Aluminium Alloy)
60
4.4.2 Tensile test results (Carbon Steel – Aluminium Alloy) 61
4.4.3 Rockwell hardness test results (Carbon Steel – Aluminium Alloy) 62
4.5.1
(Stainless Steel – Stainless Steel)
64
4.5.2 Tensile test results (Stainless Steel – Stainless Steel) 64
4.5.3 Rockwell hardness test results (Stainless Steel – Stainless Steel) 65

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LIST OF TABLES contd.
Table
No .
Caption Page
4.6.1
(Copper - Copper)
68
4.6.2 Tensile test results (Copper - Copper) 68
4.6.3 Rockwell hardness test results (Copper - Copper) 69
4.7.1
(Aluminium Alloy – Aluminium Alloy)
72
4.7.2 Tensile test results (Aluminium Alloy – Aluminium Alloy) 72
4.7.3 Rockwell hardness test results (Aluminium Alloy – Aluminium Alloy) 73
5.1 Combination of materials successfully friction welded 75
5.2 Mechanism of friction welding 75

xiii
ABBREVIATION AND NOTATION
Fig Figure
UTM Universal Testing Machine
RFW Rotary Friction Welding
C Carbon
Mn Manganese
P Phosphorus
Si Silicon
Al Aluminium
Cr Chromium
Ni Nickel
Cu Copper
Mg Magnesium
CS Carbon Steel
SS Stainless Steel
RPM Revolution Per Minute
Max Maximum
SEM Scanning Electron Microscope

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CHAPTER 1
INTRODUCTION
1.1 Friction welding
Friction welding is one of the solid-state welding process in which two work pieces are joined
under a pressure providing an intimate contact between them and at a temperature essentially
below the melting point of the parent material. Mechanical energy produced by friction in the
interface of parts to be welded is utilized.
The components to be joined are first prepared to have smooth, square cut surfaces. One part
is held stationary and the other part is mounted in a motor driven chuck or collet and rotated
against it at high speed. A low contact pressure may be applied initially to permit cleaning of
the surfaces by a burnishing action. This pressure is then increased and contacting friction
quickly generates enough heat to raise the abutting surfaces to the welding temperature. As
soon as this temperature is reached, rotation is stopped and the pressure is increased to
complete the weld. The softened material is squeezed out to form a flash. A forged structure is
formed in the joint. If desired, the flash can be removed by subsequent machining or grinding
operations. Friction welding has been used to join steel bars and tubes up to 100mm in
diameter.
1.2 Rotary friction welding
Rotary friction welding is a controlled machining process for joining similar or dissimilar
combinations of materials. The ultimate goal of rotary friction welding is to have a 100% weld
throughout the full joint interface. This means, given suitable materials, the interface strength
is equal in strength to that of the parent metals. This process yields a high-strength, low-stress,
small heat affected zone weld with no porosity, and in most cases eliminates the need for
costly pre-machining or costly tooling.

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This type of welding is extensively used in the industries like aerospace, automobile,
agricultural, construction, oil & gas, military, etc., because the welds are of forged quality.
This creates a bond strong enough to handle the high stress and torque required of heavy
machinery components including hydraulic piston rods, rear axles, gears, etc.
There are three types of rotary friction welding;
1. Continuous drive rotary friction welding,
2. Stored energy friction welding, and
3. Combined (hybrid) friction welding.
1.2.1 Continuous drive friction welding
In continuous drive friction welding, electric motor is directly connected to the machine
spindle. This energy source is infinite with respect to time, and is applied to the interfacing
materials until proper heat is obtained. Speed is held constant for a selected time or distance,
as pressure is varied. When the desired heat is achieved, the rotating component is stopped
and a forging load is applied to complete the joining process, making the work becomes one
part. Rotary friction welding with conventional lathe is an example of continuous drive
friction welding.
Following are the various processes that happen during rotary friction welding:
 Heat generation and dissipation
 Abrasion of common surfaces due to friction
 Plastic deformation
 Cold working and re-crystallization of metal heated to high temperature
 Inter-diffusion of metal and penetration of macroscopic metal parts from one piece
into other
 Continuous formation and destruction of connections between the friction surfaces
The quality of weld and efficiency of the friction welding process depends on the relative
speed of the friction surfaces and on the axial force applied during the heating period.

3
1.2.2 Stored energy friction welding
In stored energy friction welding, energy is provided by the machine‟s kinetic energy that is
stored in a rotating system. The energy available in a stored energy system is finite. When the
desired rotational speed is achieved, kinetic energy is transferred into the freely rotating part.
Constant forge pressure is applied until a plastic state is reached. Rotation stops due to
controlled pressure when the desired total displacement length of material (upset) is met.
Rotational speeds are normally higher than direct drive friction welding. Inertia friction
welding is an example of stored energy friction welding.
1.2.3 Combined (Hybrid) friction welding
The combined friction welding is a combination of continuous drive rotary friction welding
and stored energy friction welding. It has advantages in joining parts with high capacity. This
method is also sometimes termed as flywheel induced friction welding. The essential welding
parameters are rotational speed, friction force on the surface, the length of friction time, and
forging time on the surface, forging time and time of brake.
1.3 Other friction welding techniques
1.3.1 Radial friction welding: A method whereby hollow components can be joined by
using an intermediate ring which is rotated between them while subjected to radial forces.
These forces can be generated by either compressing or expanding the ring. The only
difference from the conventional rotary friction welding is that both hollow components are
fixed in the radial friction welding.
1.3.2 Friction stud welding: A method whereby a solid or hollow component (stud) is
friction welded to a larger component.
1.3.3 Friction surfacing: A method deposition whereby friction between the surfacing
material and the substrate is used to provide the thermo-mechanical conditions for adhesion.
1.3.4 Friction taper plug welding: A method whereby solid or hollow tapered
component is friction welded into a tapered hole in the other component.

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1.3.5 Friction taper stitch welding: A method according to friction taper plug welding
using solid components where a series of single plug welds are overlapped.
1.3.6 Friction-stir welding: A method whereby a non-consumable tool is rotated
between the butting or overlapped surfaces of two components and translated to generated
heat and material flow and a consequent friction weld.
1.3.7 Friction seam welding: A friction welding method whereby a consumable
material is rotated and translated between the butting surfaces of two components, E.g: two
sheets or plates.
1.3.8 Friction lap seam welding: A technique where a high speed non consumable
rotary wheel is offered against two components, which are overlapped, then translated to
effect a friction weld between the components.
1.3.9 Friction plunge welding: A technique whereby a hard material component with a
specially machined re-entrant feature is friction welded into a component of softer material to
produce both a mechanical lock and a metallurgical bond.
1.3.10 Friction co-extrusion cladding: A method whereby an inner component can be
clad with an outer component as they are rotated and forced co-axially through specially
shaped die. For long parts the die can be rotated.
1.3.11 Friction hydro-pillar processing: A method whereby a solid rod or tubular is
rotated, under an axial force, into a cavity in order to completely fill the cavity. The method
can be used for repair, fabrication, cladding and reprocessing of materials.
1.3.12 Linear friction welding: A method in which one component is moved in a linear
oscillating motion relative to and in contact with the mating face of another component.

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1.3.13 Thermoplastic friction welding
There are two types of thermoplastic friction welding techniques;
a) Linear vibration welding, and
b) Orbital welding
a) Linear Vibrational Friction Welding: In vibrational welding process, components are
brought in contact under pressure. The components are then allowed to vibrate perpendicular
to pressure applied in such a way that sliding action takes place against each other. As a result
joint is fused with the help of frictional heat along with the lateral forces.
b) Orbital Friction Welding: In orbital friction welding, the components are allowed to
rotate in a small size orbit, against each other. After attaining the required heat, the orbiting
faces of components are brought to one axis by applying more pressure.
1.4 Basic principle of friction welding
Metals are made up of positive ions „floating‟ in a „sea‟ of electrons. In principle, when two
pieces of metal are brought together under pressure they form one piece. Bonding of the
materials is a result of diffusion of their interface atoms. In friction welding, the surfaces are
rubbed together to burn off the oxide and surface contamination layers and bring the atoms in
close enough proximity to bond. The Fig. 1.1 shows the basic principle of friction welding
technique.

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In a practical situation metal pieces do not spontaneously bond to each other and form one
piece. This is because even polished metal surfaces have a layer of oxide and surface
contamination. They are also not smooth enough for the atoms to be brought close enough to
bond.
In friction welding, the surfaces are rubbed together to burn off the oxide and surface
contamination layers and bring the atoms in close enough proximity to bond. If the bond is
strong, inter-metallic layer is removed from the weld interface. Sufficient axial pressure may
be applied to bring two metallic parts close enough to the mating surfaces. This pressure can
be increased during upset stage of friction welding. Sufficient temperature may be required to
the formation of inter metallic bonding.
1.5 Advantages of friction welding
1) High quality welds can be made in a short cycle of time.
2) Filler material and flux are not required.
3) The process is suitable for welding most of the common metals.
4) This process is capable to join similar and dissimilar metal combinations.
5) Thermoplastics can also weld with this technique.
6) Easy to operate the equipment.
7) Less time is required.
8) The level of oxide films and surface impurities are limited.
9) When compared to resistance butt welding creates better welds at lower cost and
higher speed, lower levels of electric current are required.
10) Heat affected zone is very small.
11) When compared to flash butt welding, less shortening of the component.
1.6 Disadvantages of friction welding
1) Process limited to angular and flat butt welds.
2) Only used for smaller parts.
3) Complicated when used for tube welding.
4) Hard to remove flash when working with high carbon steel.
5) Requires a heavy rigid machine in order to create high thrust pressure.

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1.7 Limitations of friction welding
1) The welding area of at least one part must be rotationally symmetrical to welding
plane. Typical part geometries that can be friction welded are: bar to bar, bar to tube,
bar to plate, tube to tube and tube to plate.
2) This process is normally limited to making flat and angular (or conical) butt joints.
3) The material of at least one component must be plastically deformable under the given
welding conditions. For example alumina can be joined to aluminium.
1.8 Objectives of the work
1) To study the possibilities of rotary friction welding with similar and dissimilar metals
as per the given combinations.
2) To find out the various mechanical and metallurgical properties.
3) To study whether the weld strength will be equal or more than the strength of the
parent metal.
4) To study the rotary friction welding with conventional lathe is a feasible process.
5) To find out the best parameters and whether which can be controlled and varied.
6) Arrive at a conclusion whether the joint can be used for any applications.

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CHAPTER 2
LITERATURE REVIEW
2.1 Introduction
In continuing the report for project “Evaluation of mechanical and metallurgical properties
of metals joined by rotary friction welding with conventional lathe”, literature review is
important in order to study the basic knowledge about the subject of the project. Literature
review is a process to search, collect, analyses and concluded all debates and issues raised
in the work that been done in the past. It also provide the examples, case studies and other
relevant work that be done by other people in the past. It gives the chance to investigate and
read the subject that user may not have thought about before. The literature review focuses
on the various theory and basic knowledge used in the project.
2.2 Fact and findings
There is lot of techniques used to gather information that related to the project through
internet, book, journal, etc. These initial documents will provide some valuable information
to determine the basic view of the project. The theory and concept from the past research,
references, case studies, and other can be applied in order to understand the dissertation.
2.3 What is friction welding?
Friction welding is a completely mechanical solid phase process in which heat is generated
by friction [1]
to produce a high integrity joint between similar and dissimilar metals.
2.4 Why friction welding?
A bonded joint is formed using no filler metal, flux or shielded gas. This process is
environmentally clean, no arcs, sparks, smoke or flames are generated during friction
welding. Surface preparation/ cleanliness are not significant with most materials since the

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process burns through and displaces surface impurities. During the friction welding process
there are narrow heat affected zones. This process is suitable for welding most engineering
materials and is well suited for joining many dissimilar [2][6]
combinations. In most cases, the
weld strength is strong or stronger than [3]
the weaker of the two materials being joined.
Operators are not required to have manual welding skills. Friction welding only required
simple integration into the manufacturing area. This process can be easily automated for
mass production. Welds are made rapidly compared to other welding processes. Plant
requirements (space, power, special foundation, etc.) are minimal for the friction welding
process.
2.5 Theory of friction welding
Friction welding consists of a complex of interrelated processes; heat generation and
dissipation and abrasion of common surfaces due to friction [4]
; plastic deformation, cold
working and recrystallization of metal heated to high temperatures; inter diffusion [5]
of
metal and penetration of macroscopic metal parts from one piece into other; continuous
formation and destruction of connections between the friction surfaces, etc.
2.6 History of the friction welding
According to the American Welding Society, the origins of friction welding date back to
1891, when the first patent on the process was issued in the USA. More work progressed
throughout Europe as more patents were issued from 1920 to 1944 and in the Soviet Russia in
1954. In 1954, this technique has successfully implemented by A.I. Chudikov from Russia
(USSR) with a modified lathe using round metal bars. In the 1960's, friction welding was
further developed in the USA by AMF, Caterpillar, and Rockwell International. Rockwell
built its own machines to weld spindles to truck differential housings, AMF produced
machines to weld steering worm shafts, and Caterpillar‟s machines welded turbochargers and
hydraulic cylinders.
Friction has been used to weld parts for both new make and for repair for many years. The
friction welding family has many different variants, including rotary friction welding (direct
drive, inertia, and hybrid), linear friction welding, and more recently, friction stir welding
(FSW). In e ach case, friction heats the material to a plastic state in conjunction with an

10
applied force to create the weld. Friction welding often produces welds with superior
mechanical properties to that of the parent materials. The weldment produced by this method
often has less distortion than fusion welding methods (such as arc welding, laser welding,
etc.) In addition that dissimilar material combination can be welded that are not possible with
fusion welding processes.
2.6.1 Historical development in friction welding
A historical development [14]
in friction welding is explained in the Table 2.1 below.
Table 2.1 – Historical development in friction welding
1954
A.I. Chudikov of U.S.S.R. succeeded in the experiment of friction welding,
using a modified lathe and round metal bars. U.S.S.R. Electric Welding
Machine Research Institute took up the idea and started the research and
development from around 1956.
1956
U.S.S.R. Electric Welding Machine Research Institute took up the idea and
started the research and development.
1957
The Institute developed and made public the friction welding machine MST-1.
After this announcement, many countries started research and development of
the technology for practical applications.
1958
Development in U.S.S.R. entered the stage that the technology was introduced
in the production processes.
1958
British Welding Research Association (BWRA) succeeded to produce a
prototype of friction welding machine. AMF Corp. of the U.S. also introduced a
prototype of friction welding.
1960
"Friction joining of metals" by VILL of VNIIESO was introduced as a research
data in Japan. This triggered ardent investigations and researches on the friction
joining.
1960
Machine tool research group brought back useful information from the USSR
designed, manufactured and started marketing specialized manufacturing
equipment.
1962
Toyoda Automatic Loom Works Ltd. developed the first brake-type friction
welding machine for commercial industrial use in Japan
1964
The Friction Joining Research Conference was founded. It was renamed later as
the Society for the Study of Friction Joining and further to the Friction Joining
Association, which continues activities to now.
1973
Izumi Machine Mfg. Co. of Japan began consignment manufacturing of Toyoda
Automatic Loom Works, Ltd friction welding equipment.

11
1994 JIS 3607 Standard for the friction joining work of carbon steel was enacted.
1998
Izumi started commercial application of a friction welding machine
incorporating NC control that is compatible with the production of propeller
shafts and other parts.
2002
Izumi started commercial application of a friction welding machine capable of
use on extremely small diameter material (Ø1.6) used for drills, sensor shafts
and other such applications.
2004 Friction welding of plastics
2006 Scientific Optimization Techniques used to study friction welding
2009 Use of interlayers during friction welding
2011 Response surface methodology used to study friction welding
2014 Friction welding of 3D printed objects [15]
2015
Austrian premium chain manufacturer Pewag presented its newly developed
Pewag Hero Friction-welded chain. This innovation marks the starting point of
a new era in chain manufacturing.
2.7 Research work on friction welding
Table 2.2 shows some of the latest research work related to friction welding [1-12].
Table 2.2 – Recent research work on friction welding
Sl.
No
Title Author Year Contributions
1 Friction Welding
Process of
Aluminium 5083
Alloy with Mild
Steel.
V. Ganesh,
N. Parthasarathi, M.
Sivanesh,
S. Pravin Joseph
Rajkumar &
P. Giftan Samuel
2016 Conducted the experiment with
combination of Aluminium
5083 and Mild Steel and they
found that the friction welding
was very successful.

12
Sl.
No
2 Effect of Friction
Welding
Parameters on the
Tensile Strength
and Microstructural
properties of
Dissimilar AISI
1020-ASTM A536
Joints
Radoslaw
Winiczenko
2016 They conducted the
experiment on the friction
welding equipment and made
an empirical relationship
developed to predict the
ultimate tensile strength at
90% confidence level. They
also proved that when
friction force and friction
time increases, tensile
strength also increases. It
was approximately to 87% of
the strength of the base
metal.
3 Joining of AISI
1040 Steel to 6082-
T6 Aluminium
Alloy by Friction
Welding
C.H. Muralimohan,
S. Haribabu,
Y. Hariprasada
Reddy,
V. muthupandi,
K. Sivaprasad
2015 They successfully joined by
friction welding process and
arrived at a conclusion that
the strength of the welds
decreased with an increased
friction time. If the
optimized welding condition
is achieved maximum
strength will be more than
the strength of the base
metal. Hardness test shows
that hardness value increases
with forging pressure.
4 Effect of
Mechanical
Properties and
Microstructural
Characteristics of
Friction Welded
Austenitic Stainless
Steel Joints
N. Mathiazhagan,
T. Senthilkumar &
Balasubramanian
2015
In this investigation,
commercial AISI 304
austenitic stainless steel
specimens were joined by
friction welding process and
the joint performance were
evaluated mechanically and
metallurgically. Optimum
welding parameters yielded
near 95% joint efficiency.

13
Sl.
No
5 A Study on
Mechanical and
Metallurgical
Properties of
Welded Dissimilar
Materials
Sriram Ravi &
Ramadoss R.
2015 Friction welded process
successfully done with AISI
316L-Copper and AISI 316-
Copper. They found the
hardness at the copper side was
high at weld zone and hardness
at the SS side was low at the
weld zone. The highest tensile
strength obtained in AISI 316
and Copper was 270 Mpa and
lowest was 142 Mpa. In case of
AISI 316L and copper was 260
Mpa and lowest tensile
strength was 40 Mpa.
6 Experimental
Investigation of
Rotary Friction
Welding
Parameters of
Aluminium (H-30)
and Mild Steel
(AISI-1040)
B. Seshagirirao,
V.Sivaramakrishna
&
G.Saikrishnaprasad
2015 Conducted the experiment on
medium duty lathe at different
speeds, with 10mm and 12mm
diameter round bars. They
found that the Aluminum H30
and AISI 1040 Steel can be
successfully joined by rotary
friction welding. In the
experiment, 12mm diameter
MS-MS bar welding process
has generated highest
temperature of 767 ºC.
7
Tensile Properties
and Microstructural
Characteristics of
Friction Welded
Similar Joints of
Aluminium Alloys
S.R. Sundara
Bharathi, A. Razal
Rose & V. Bala-
subramanian
2015 With the experiment, they
proved similar joints of
Aluminium Alloys (AA 2024 &
AA 20240) can be successfully
welded. After tensile testing
they found that weld strength
will be less than the strength of
the base metal. In hardness test
they found weld joint hardness
is same as the hardness of the
base metal.

14
Sl.
No
8 Design and
Fabrication of
Rotary Friction
Welding on Lathe
Machine
Rama rao, A. Kiran
Kumar yadav & G.
Sai Krishna Prasad
2015 They conducted the experiment
on a lathe machine with MS-
MS, MS-Al, Cu-Brass and Al-
Al. material combinations.
Their finding was a lathe can
perform friction welding up-to
20mm diameter and they could
not make a firm joint between
Cu-Brass and MS-Al dissimilar
material combinations.
9 The Mechanical
Properties of 1060
Aluminium Joint
by Continuous
drive Friction
Welding
Qingzhe Li,
Ranfeng Qiu,
Zhongbao Shen,
Longlong Hou &
Lihu Cui
2015 They conducted continuous
drive friction welding of 1060
Aluminium under different
friction pressure and forge
pressure. Tensile test result
showed that joint strength is
less than strength of the base
metal. The best parameter they
found, friction pressure is 1.5
MPa, upset pressure is 2.5 MPa,
and friction time is 2.5 sec.
10 Development of
Al/Cu Dissimilar
Joint by New
Friction Welding
Method
Yongbo Hu, Ryoji
TSUJINO, Takeshi
HIGASHI,
Yoshiaki UEDA &
Manabu IGUCHI
2014 Dissimilar joint of Aluminium
Alloy 2017 and pure Copper
was friction welded. 60% joint
efficiency larger than that in the
conventional process was
obtained.
11 Evaluation of
Mechanical and
Metallurgical
Properties of
Dissimilar
Materials by
Friction Welding
Shanjeevi C.,
Satish Kumar S. &
Sathiya P.
2013 Austenitic Stainless Steel and
Copper joints are successfully
friction welded. They found that
use of higher friction pressure
with low upset pressure
increases the tensile strength of
the friction welded joint. The
hardness shows higher in parent
metal than in Heat Affected
Zone of Stainless Steel
materials

15
Sl.
No
12 An Experimental
Assessment of the
Bond Strength of
Friction Weldment
Between AA-6061
and AA-6351
S Thileepan,
S. yuvanarayanan,
S. Jayakumar,
Vasanthan &
R. Adalarasan
2011 Conducted the rotary friction
welding between Aluminium
Alloy AA-6061 and AA-6351 on
friction welding machine. The
diameter of the test specimen was
18mm. The hardness at the
weldment was higher than the
hardness of the base metals.
Hardness of the weldment
increases with increase in
rotational speed.
2.8 Material combinations weldable by friction welding [20]
The data given in the figure 2.1 shows the possible combination of similar and dissimilar
materials that can be joined by friction welding.

16
2.9 Friction welded components and their applications [18]
2.9.1 Aerospace Industry
Aerospace heat pipe
(Aluminium)
Piston for aircraft pump
(Stainless steel)
Aircraft hook bolt
(Nickel-heat resistant)
Stator vane adjustor lever
(Titanium)
Ball screw actuator
(Steel-Medium carbon
alloy)
Jet engine fan shaft
Landing gear component
alloy)
Fan blade rotor
Cluster gear
(Steel-Low carbon alloy
(gear steel))
Fig. 2.2 - Friction welded components and their applications in
Aerospace industry

17
2.9.2 Agriculture/ Construction Industry
Gear welded-clutch drum
(gear steel))
Pin assembly
alloy)
Front axle yoke shaft
alloy)
Trailer axle
alloy)
Rear axle welded to hub
alloy)
Track roller bushing
Copper alloy/
Steel-Low carbon)
Diesel engine piston
alloy)
Chain drive sprocket
alloy)
Water pump gear
(gear steel))
Agriculture/ Construction industry

18
2.9.3 Automotive Industry
`
Universal joint assembly
(Steel-Medium carbon/
Steel-Low carbon)
Rear axle housing tube
(Steel-Medium carbon/
Steel-Llow carbon)
Automotive transmission
Component
(Steel-Low carbon)
Bi-metallic exhaust valve
(Nickel-heat resistant/
Steel-Medium carbon)
Front wheel drive shaft
alloy)
Turbo charger
(Nickel-heat resistant/
Steel-Medium carbon)
Transmission gear
(gear steel)
Wheel rim
(Aluminium alloys)
Drive extension
(gear steel))
Automotive industry

19
2.9.4 Oil and Gas Industry
High pressure valve body
alloy)
Geological core drill
alloy)
Oil well head manifold
alloy)
High pressure valve body
alloy)
Butterfly valve
(Stainless steel SS 304)
Sucker rod
alloy)
Oil well drill pipe
alloy)
Oil pump gears
(Steel-Low carbon)
Oil well drill pipe
alloy)
Oil/Gas industry

20
2.9.5 Military
Impact wrench extension
alloy)
Adjusting link for tracked
vehicles (Steel-Medium
carbon alloy)
Mortar round
alloy)
Midcase bomb assembly
alloy)
Front bomb case assy.
alloy)
Wind screen to
projectiles (Aluminium
alloys/Tungsten)
Drive shaft torque tube
alloy)
Fuze liner
(Steel-Low carbon)
Impact wrench extension
alloy)
Military industry

21
2.10 Variables and parameters that govern the quality of the
welded components
The variables and parameters [20]
that govern the quality of the welded components during
continuous drive rotary friction welding are given in the Table 2.3 below.
1) Frictional pressure: The pressure applied normal to the faying surfaces during the
time that there is relative movement between the components.
2) Forging pressure: The pressure applied normal to the faying surfaces at the time when
relative movement between the components is ceasing or has ceased.
3) Friction time: The time during which relative movement between the components takes
place at rotational speed and under application of the friction force.
4) Braking time: The time required by the moving component to decelerate from friction
speed to zero speed.
5) Forge time: The time for which the forge force is applied to the components.
6) Linear feed: This is the lateral movement of the stationary work-piece relative to the
rotation of the rotating work-piece.
7) Medium in which process takes place: This will depend upon the site conditions.
Sometimes friction welding can be done in the air conditioned atmosphere or in vacuum
chambers. The result will be something different.
Sl. No.
Machine Material
1 Friction pressure Type of metal
2 Forging pressure Part configuration
3 Friction time Size
4 Braking time Initial condition of the friction surface
5 Forge time Shape of the parts to be welded
6 Linear feed
7 Medium in which process takes place
Table 2.3 - Variables and parameters govern the quality of the friction weld

22
2.11 Plot of Welding parameters versus Time in continuous drive
friction welding
Fig. 2.7 shows the generalized plot of the „welding parameters versus time‟ in continuous
drive friction welding process [21]
.

23
2.12 Characteristics of friction welded components[20]
Possible friction welded defects, causes, remedies, etc. are illustrated in the Table 2.4.
Table 2.4 – Characteristics of friction welded components
Desig-
nation
Explanation Diagram Usual test
methods
Causes Remedy Remarks
1) Shape deviation
Axial
mis-
alignment
Misalign-
ment of
parallel
axes of
components
Measure-
ment, visual
examination,
macroscopic
Clamps,
geometrical
inaccuracy,
overhang too
long, poor
component
preparation,
angularity
Adjustment
of clamps,
check
component
geometry,
reduce free
length,
better
component
preparation
Critical when
friction
welding thin
walled tubes
and materials
which are
very
dissimilar
Angular
deviation
Axes of
components
misaligned
Measure-
ment, visual
examination
Clamping
length
too short,
overhang too
long,
loose clamps,
axial force
too great
Improve
clamping,
decrease
free length,
tighten
clamps,
reduce axial
force
Critical
mainly when
thin-walled
tubes
Parts
overlying
Lateral
deviation of
one or both
work pieces
Visual
examination,
macroscopic
Welding
parameters,
component
geometry,
overhang too
long, axial
misalignment
Work piece
preparation,
angularity
Change Critical
mainly when
friction
welding thin
walled tubes
and
components
of very
dissimilar
materials
Deforma-
tion of
work
pieces
Undesired
Change in
geometry
Measure-
ment, visual
examinations
Insufficient
support, axial
strength too
high,
overhang too
long, tooling
wear
Adjust
clamping,
increase
rigidity
Occurs when
welding thin
walled work
pieces

24
Desig-
nation
methods
2) Unsatisfactory joint
Interface
defect
Incomplete
bonding
Macro and
micrographs
examination
of fractured
ends, non-
destructive
tests
Clamps,
welding
parameters,
work-piece
preparation,
centrally
drilled holes
Change
parameter,
better
work-piece
preparation
Undercut Undercut
below
component
diameter
Visual
examination,
magnetic
particle test,
dye pene-
tration test,
ultra-sonic
test
Welding
parameters,
component
preparation,
work holding
alignment.
Change
parameters,
better
component
preparation
Energy input
too low, burn
off (weld
time) too
short
Inclusions Non-
metallic
inclusions in
the welding
area
Macro/
micrographs,
examination
of fracture
Component
preparation,
welding
parameters,
dirty central
hole, high
level of
inclusions in
component
metal
Clean
welding
surfaces, if
necessary
drill central
hole, use
clean
material
Cracks
Partial non-
coalescence
of compo-
nents on the
periphery of
the weld
interface
Dye
penetration
test,
magnetic
particle test,
Macro and
micrographs
Heat
treatment
before/after
welding,
change
parameters,
use different
materials
Low critical
cooling rate
e.g.: When
using high
carbon steels
remove flash
before heat
treatment

25
Desig-
nation
methods
…… Unsatisfactory joint
Cracks
Non-
coalescence
in the
middle
Sections,
Ultrasonic
Test
Hardening,
incorrect
heating, short
weld time
Heat
treatment
before/after
welding,
change
parameters,
increase
axial force,
bevel end
On the
periphery or
in the heat
affected
zone (HAZ)
Sections,
visual exami-
nation, eddy
current test,
ultrasonic
test, dye
penetration
test, etc.
Hardening,
incorrect
heating,
presence of
carbides,
MnS
inclusion
In the
sharply
delineated
transition to
flash
Macro and
micrographs,
visual
examination,
eddy current
test, dye
penetration
test,
magnetic
particle test
Forging
pressure too
high,
overhang too
short
Lower
forge
pressure,
modify
parameters,
increase
rotational
speed
Appears in
heat affected
zone (HAZ)
near weld
line due to
hydrogen
Non-
destructive
testing
Presence of
hydrogen in
one or both
components,
e.g.: Castings
+ plated
metals
Apply
hydrogen
release heat
treatment
Can occur
upto 1000
hours after
welding

26
Desig-
nation
methods
3) Microstructural features
Gross
distortion
in grain
structure
Grain
structure of
base
material
distorted
due to
friction
welding
Metallo-
graphy
Weld
parameter
Incorrect
Modify
parameters,
increase
RPM,
decrease
axial force
Possible
cause for low
ductility in
the joint area,
especially if
non-metallic
inclusions
present
Inter-
metallic
phases
Diffusion of
elements
Macro/
micrographs
Welding
parameters in
particular for
dissimilar
materials
components
Change
material
and/ or
parameters,
e.g.
decrease
welding
time
If present,
severely
embrittle
weld
Carbide,
oxide,
nitride,
agglome-
rations in
the welding
zone
Appear on
welding
surfaces
after
welding
Macro/
micrographs,
ultrasonic
test to a
certain
degree
Better
homoge-
neity of
material,
change
weld para-
meters, e.g.
shorten
welding
time
Peaks and
troughs in
hardness
Hardness
and / or
consistency
values differ
from those
of base
material
Determina-
tion of
distribution
of hardness
values
Welding
parameters,
material,
material
preparation
Change
parameters,
heat
treatment

27
Desig-
nation
methods
4) Flash deviations
Burr
Vertically in
the flash
Visual
examination,
magnetic
particle test,
dye pene-
tration test
Forging
pressure too
high,
insufficient
heat, vertical
fissures in
base material
Change
parameters,
Increase
rotation
speed
Occur in free
machining
steel alloys,
tooling steel
containing W
Extrusion of
material all
the way
around
Visual
examination
Unknown Unknown Consequence
unknown
Material
protrudes in
a spiral
shape at
irregular
intervals
Visual
examinations
Insufficient
heat input
Increase
energy
input by
increasing
RPM
At regular
intervals
Visual
examination
Visual
Unknown Unknown
Secondary
Flash 1
Secondary
Flash II
Assyme-tri-
cal welding
flash
Displace-
ment of
Welding
surfaces
Visual
examination
Very
dissimilar
materials or
work pieces
Welding
parameters
Change
welding
parameters,
increase
friction
force
Flash
restriction
Deforms
against
tooling
Visual
examination
Inadequate
overhang and
poor tooling
Increase
overhang
and
improve
tooling
Reduce
welding
pressures,
can increase
cooling rate

28
CHAPTER 3
EXPERIMENTAL WORK
3.1 Introduction
In this experimental work, conducted experiment on NH22 model lathe manufactured by
Hindustan Machine Tools Limited. This is a high speed precision lathe having 16 numbers
of spindle speeds from 40 to 2040 RPM in forward direction and 7 numbers spindle speeds
from 60 to 1430 RPM IN reverse direction.
In order to conduct the experiment, selected 10mm diameter polished rod of various metal
combinations and have made three sets of experiments in seven combinations with two
different spindle speeds of 1210 RPM and 2040 RPM. The length of specimen used for tensile
test is 300mm and length of other specimens for hardness test and SEM test are 100mm each.
During the test, one specimen of 100mm or 300mm length work piece was held on three jaw
chuck fixed on the lathe machine. This is a rotating part, which rotated either in 1210 RPM or
2040 RPM. Other work piece was held on the special tailstock attachment which capable to
hold on the tailstock of the lathe. This is a non-rotating part. The tailstock attachment is used
for measure axial pressure applied during friction and forge.
3.2 Material selection
Following combination of materials with two spindle speeds was conducted.
1) Carbon Steel (20C15) - Carbon Steel (20C15)
2) Carbon Steel (20C15) - Stainless Steel (SS 304)
3) Carbon Steel (20C15) - Copper (C10300)
4) Carbon Steel (20C15) - Aluminium Alloy (6063)
5) Stainless Steel (SS304) - Stainless Steel (SS 304)
6) Copper (C10300) - Copper (C10300)
7) Aluminium Alloy (6063) - Aluminium Alloy (6063)

29
3.3 Specification, properties and application of metals
3.3.1 Carbon Steel (20C15)
This is a low carbon steel containing following alloying elements and properties and it is used
for making pump shafts, machined components, valves, dairy equipments, fasteners, machine
tools, studs, bolts, hinges, handles, surgical & medical parts, threaded bars, etc. Table 3.1
shows the material composition of carbon steel. Iron is the remaining major element.
Table 3.1 – Material composition of Carbon Steel
C Mn P S Si Al
0.16-0.24% 1.30-1.70% 0.035% Max 0.035% Max 0.10-0.35% 0.02 % Min
 Tensile Strength - 600-700 N/mm2
 Yield Strength - 350-550 N/mm2
 Elongation - 8-25%
 Hardness - 82-93 HRB
 Melting temperature - 1450 – 1510 ºC
 Thermal conductivity - 25 W/m ºK
 Density - 7.8 g/cm3

30
3.3.2 Stainless Steel (SS 304)
It is the most widely used austenitic stainless steel, popularly known as 18/8 stainless steel, it
has excellent corrosion resistance and forming characteristics. Used in chemical,
petrochemical and fertilizer industries, and as equipment in dairy, food processing,
pharmaceutical industries, cryogenic vessels and as heat exchangers in air conditioning
refrigeration, for machinery in paper, pulp and textile beverage sectors, etc. The Table 3.2
shows the material compositions of stainless steel. Iron is the remaining major element.
Table 3.2 – Material composition of Stainless Steel
C Mn P S Si Cr Ni
0.070% 2.0% 0.045% 0.030% 0.75% 17.50-19.5% 8.0-10.5%
 Yield Strength - 205-310 N/mm2
 Elongation - 40%
 Hardness - 92 HRB
 Melting temperature - 1673 - 1723 ºC
 Thermal conductivity - 14-17 W/m ºK

31
3.3.3 Copper (C10300)
This is a high purity, high conductivity, low phosphorus copper and has a very good welding
properties and resistance to hydrogen embrittlement. It has excellent hot and cold forming
properties and a good corrosion resistance in water and especially in atmosphere. It has wide
applications in the field of telecommunications, submarine cable strips, wave guide tubing,
commutators, tubular busbars, terminals, etc. The Table 3.3 shows the material composition
of copper (C10300).
Table 3.3 – Material composition of Copper
Cu P Impurities - - -
99.9% 0.013-0.055% 0.06% - - -
 Yield strength - 69-345 N/mm2
 Elongation - 20%
 Melting temperature - 1083 ºC

32
3.3.4 Aluminium Alloy (6063-T6)
This is a medium strength alloy. It is normally used in intricate extrusions. It has a good
surface finish; high corrosion resistance is suited to welding and can be easily anodized.
Following are the alloying elements and properties of the aluminium alloy (6063). The Table
3.4 shows the material composition of aluminium alloy (6063).
Table 3.4 – Material composition of Aluminium
Cu Mg Si Fe Mn *Others
0.10% 0.40-0.90% 0.30-0.70% 0.60% 0.30% 0.40%
* Others – titanium and other grain refining elements
 Tensile Strength - 215 N/mm2
 Yield Strength - 170 N/mm2
 Elongation - 8%
 Melting temperature - 655 ºC
Fig. 3.4 shown below is the Aluminium Alloy (6063) work pieces required for the rotary
friction welding.

34
Fig. 3.5 to 3.9 shows the experimental setup of rotary friction welding. Following are the
main components involved in this system;
 HMT make NH22 precision lathe with 3 jaw chuck, having 16 numbers of spindle
speeds from 40 to 2040 RPM in forward direction and 7 numbers spindle speeds from
60 to 1430 RPM in reverse direction.
 Specially built tailstock attachment, consists of 2T hydraulic jack, 3/4” drill chuck,
MT5 drill sleeve, 0-100 Kg/cm2
hydraulic pressure gauge, special clamp to prevent
rotation of drill chuck and work piece, etc.
 Infrared thermometer, MetroQ make, Model-MTQ 580, suitable for -58ºC to 580ºC
temperature measurement, resolution 0.1º C, emissivity adjustable to 0.1 to 1.0,
accuracy ≥ 100 ºC ± 2% / ≤ 100 ºC ± 2 ºC, response time ≤ 5 seconds.
 Timer to check the friction time and forge time.
 Intermediate support, provided in the tool post which supports the work-piece as wells
as enables the work piece to slide horizontally freely through the hole provided in the
support.
 Rotating work pieces, fixed in three jaw chuck provided in the lathe head stock; which
will be rotated either 1210 RPM or 2040 RPM and non-rotating work piece fixed in the
drill chuck.

35
3.5 Experimental procedure of rotary friction welding
Following are the different procedures followed to conduct the experiment.
1) Work piece preparation
2) Work piece setting
3) Operational steps in welding
4) Data measurements
5) Testing and analysis
3.5.1 Work piece preparation
Round metal bars of Carbon steel (20C15)/ Stainless steel (SS 304)/ Copper (C10300)/
Aluminium alloy (6063) were precision machined to 10mm diameter and cut into required
length and sufficient quantity. For tensile testing of the work pieces; length of each work
piece were 300mm length and work piece for hardness test and SEM test were 100mm length.
Each ends were finished with facing operation and removed grease, dirt and other impurities
from the end surface. Fig. 3.10 shows an image of 100mm length work pieces for friction
welding.

36
3.5.2 Work piece setting
Work pieces are to be welded, first set in to the lathe chuck provided in the headstock and
drill chuck provided in the tailstock attachment so that their axes lie within the limits
specified for concentricity and alignment. The overhang should not be so short as to cause
unacceptable chilling of the component or so long as to cause unaccepted misalignment or
vibration of the opposing faces during the friction and forge phases. In this experimental
setup an intermediate support for non-rotate work piece has provided to overcome the
misalignment. In order to find the axial load, hydraulic pressure gauge fixed on the tailstock
attachment is used. To prevent the rotation of drill chuck and work-piece, an additional
arrangement is provided in the tailstock attachment.
3.5.3 Operational steps in welding
a) Pre-contact
Parts are mounted in the 3 jaw chuck in the
head stock (rotating part) and drill chuck in
the tail stock attachment (fixed part), provided
in the lathe machine. Rotating part is spun up
to the speed of either 1210 RPM or 2040
RPM. Fig. 3.11 shows the arrangement of
work pieces during pre-contact state.
b) First friction
Increase the speed of rotating chuck and work
piece fixed in the drill chuck brought into
contact under light force by rotating the hand
wheel in the tailstock; force applied during
first friction is approximately 30% of the
second friction. During first friction contact
surface will be rubbed together and as a result
slight heat will be produced.

37
c) Second friction
The increased pressure brought about during second friction, causes the metal to become
“plastic” and flows outward from center to form the characteristic “flash”. Measure the
maximum temperature at the flash area by
using infrared thermometer. Once the designed
flash is accomplished, the rotation is rapidly
stopped. The process then moves to the forge
phase. Fig. 3.13 shows the arrangement of
work pieces during second friction state.
d) Forging
The forge is caused by the application of the
highest of the three process pressures. The
forge phase takes place while the components
are at a complete stop. The pressure is
maintained until the weld joint is sufficiently
cooled. This step promotes refinement of the
microstructure of the weld. Fig. 3.14 shows the arrangement of work pieces during forge
state.
e) Completion of weld
In this phase, completed the weld and allowed
sufficient time to cool the welded joint interface.
After cooling the work piece, can be removed
from the chuck for further process. Fig. 3.15
shows the arrangement of work pieces after
completion of friction welding state.
f) Flash removal
The flash can be removed from the weld interface
by conventional machining process and grinding.

38
3.5.4 Data measurements
In order to measure various data during the time of experiment, provided different
arrangements on the machine. By using the pressure gauge provided in the hydraulic jack in
the tailstock attachment helped to measure friction pressure and forge pressure applied on
the stationary work piece through tailstock hand wheel during the time of actual
experiment. Frictional time and forge time has taken with the help of digital clock. Digital
infrared thermometer has used to measure the interface temperature during the time of
friction welding. As the machine has capable to set to the constant spindle speeds of
required RPM, separate measurements on speed was not required.
3.5.5 Testing & Analysis
In order to analyze the performance of the welded joint, tensile test and hardness test were
done as per Indian standard IS 15728: 2006 (ISO 15620:2000). In addition that,
microscopic examination test were also conducted on the welded samples.
a) Tensile test
The most common type of test used to measure the mechanical properties of a material is
the tension test. Tension test is widely used to provide basic design information on the
strength of materials and is an acceptance test for the specification of materials. The major
parameters that describe the stress-strain curve obtained during the tension test are the
tensile strength, yield strength, percent elongation and percentage reduction in area.

39
As part of the experiment, conducted the tension test on universal testing machine in the
Government Engineering College, Thrissur and tested the welded components which are
friction welded with 1210 RPM and 2040 RPM in similar and dissimilar combinations. The
Fig. 3.17 is the images taken during the tensile test.
From the tension test, various parameters like yield strength, ultimate tensile strength,
breaking load, elongation (within 50mm gauge length), and percentage reduction in area,
etc. are measured and calculated. In absence of good bonding strength between joints, could
not record breaking load and yield strength for some dissimilar welded components. Fig.
3.18 is an image of friction welded joints, required for tensile test. In order to hold the
sample in the UTM, length of work piece used for friction welding were 300mm each.
b) Hardness test
Hardness is a characteristic of a solid material expressing its resistance to permanent or plastic
deformation. There are three general types of hardness measurements, which are scratch
hardness, indentation hardness and rebound or dynamic hardness. Among these three, only
indentation hardness is of major engineering interest for metals. Following are the major
material hardness testing methods used. They are;
 Rockwell hardness test
 Brinnel hardness test, and
 Vickers hardness test

40
In order to measure the hardness of the friction welded components, only Rockwell hardness
was measured. Fig. 3.19 shows the various hardness techniques used in material testing
laboratories.
 Rockwell hardness test
This hardness test uses a direct reading instrument based on the principle of differential depth
measurement. Initially a minor load is applied, and a zero datum position is established. The
major load is then applied for a specific period and removed, leaving the minor load applied.
The resulting Rockwell number represents the difference in depth from zero datum position as
a result of the application of major load. The conical diamond indenter is used mainly for
testing hard materials such as hardened steels and cemented carbides. Hardened steel ball
indenters with diameters 1/16, 1/8, 1/4, 1/2 inch are used for testing softer materials such as
fully annealed steels, softer grades of cast irons, and a wide variety of nonferrous metals.
Generally, in Rockwell testing, the minor load is 10 Kgf, and the major load is 60, 100 or 150
Kgf. The indenter used may be either a diamond cone or steel ball, depending principally
on the characteristics of the material being tested. Common Rockwell hardness scales are
shown in table 3.5 below.

41
Table 3.5 – Common Rockwell hardness scales
Rockwell
scale
Hardness
symbol
Indentor Load (Kg) Typical materials tested
A HRA Cone 60 Carbide, ceramics
B HRB 1.6mm ball 100 Non-ferrous metals
C HRC Cone 150 Ferrous metals, tool steels

42
c) Microscopic examination
Basically, SEM test being used for microscopic examination of the friction welded joint
interface and surroundings, consists of following steps.
 Sampling
 Grinding
 Polishing
 Etching
 SEM test
Sampling: Selected one set welded joint samples for this purpose. The maximum size of the
sample is limited to 10mm x 5mm. This is the maximum size of the sample to be fixed on the
holder in the SEM equipment. Hence cut the welded work-piece in to 10mm length and
reduced the diameter of the work piece from 10mm to 5mm by machining. Fig. 3.22 is
images of sample preparation job during the experimental work.
Grinding: After reduce the diameter of the welded work piece from 10mm to 5mm, removed
the scratches from the weld surface. A series of decreasing grits size are used.
Polishing: Intermediate polishing is carried out by a series of water paper containing
successively fine abrasive. In order to make specimen, scratch free surface smooth polishing
is carried out. A wheel covered with a special cloth that is charged with carefully sized
abrasive particles is used for polishing. For fine polishing, SiC fine grit size honing stick with
oil is also used.

43
Etching: Etching is carried out to reveal many of structural characteristics of metal or alloy.
In order to examine the grain boundaries appearance of metallic surface, all samples were
etched with suitable etchant. The selection of etchant depends upon the nature of the material.
Fig. 3.23 shows the etching process of samples to be tested.
SEM test: After etching the samples are examined under, scanning electron microscope to
study the microstructural changes occurred due to friction welding. Fig. 3.24 is the polished
sample pieces used for SEM test.
To find the microstructure details of the weld interface 12 samples were used, which are
similar and dissimilar metal combinations welded by rotary friction method in conventional
lathe.
Sophisticated Test and Instrumentation Centre (STIC) at Cochin University of Science and
Technology have the facility for the micro-structure evaluation (SEM Test). They used JEOL
make JSM-6390LV Scanning Electron Microscope for this purpose.

44
The Scanning Electron Microscope (SEM) uses a focused beam of high-energy electrons to
generate a variety of signals at the surface of solid specimens. The signals that derive
from electron-sample interactions reveal information about the sample including external
morphology (texture), chemical composition, and crystalline structure and orientation of
materials making up the sample. In most applications, data are collected over a selected area
of the surface of the sample, and a two dimensional image is generated that displays spatial
variations in these properties. Areas ranging from approximately 1 cm to 5 microns in width
can be imaged in a scanning mode using conventional SEM techniques (magnification
ranging from 20X to approximately 30,000X, spatial resolution of 50 to 100 nm). The
maximum magnification level for metals are limited to 3000X because if the magnification
level exceeds 3000X, resulting image quality will be very low. Fig. 3.25 is images of SEM
machine and other arrangements taken during SEM Test.

45
3.6 Observations
The Table 3.6 shows the details of the observations related to the rotary friction welding.
Table 3.6 – Observations of rotary friction welding
Sl.
No.
Material 1 Material 2
Tensile
Test
Hardness
Test
SEM
Test
Result
Friction welded with a spindle speed of 1210 RPM
1
Carbon Steel
(20C15)
Carbon Steel
(20C15)
   Very good joint
2
Carbon Steel
(20C15)
Stainless
Steel (304)
   Good joint
3
Carbon Steel
(20C15)
Copper
(C10300)
   Weak joint
4
Carbon Steel
(20C15)
Aluminium
Alloy (6063)
  * Weak joint
5
Stainless
Steel (304)
Stainless
Steel (304)
6
Copper
(C10300)
Copper
9C10300)
7
Aluminium
Alloy (6063)
Aluminium
Alloy (6063)
Friction welded with a spindle speed of 2040 RPM
1
Carbon Steel
(20C15)
Carbon Steel
(20C15)
2
Carbon Steel
(20C15)
Stainless
Steel (304)
3
Carbon Steel
(20C15)
Copper
(C10300)
4
Carbon Steel
(20C15)
Aluminium
Alloy (6063)
  * Weak joint
5
Stainless
Steel (304)
Stainless
Steel (304)
6
Copper
(C10300)
Copper
9C10300)
7
Aluminium
Alloy (6063)
Aluminium
Alloy (6063)
* While reducing the size of the welded specimen, joint broken.

46
CHAPTER 4
RESULTS AND DISCUSSIONS
4.1 CARBON STEEL (20C15) – CARBON STEEL (20C15)
4.1.1 Results & findings
Rotary friction welding between similar combinations of Carbon Steel (20C15) and Carbon
Steel (20C15) were done with spindle speed of 1210 RPM and 2040 RPM. For this purpose,
three sets of joints were made in each spindle speed. The length of the work piece used for
tensile test was 300mm each and other work piece length was 100mm each. Frictional time
and forge time was taken by using stop watch. By using infrared thermometer, weld interface
temperature was taken. Frictional pressure and forge pressure was taken as constant of 40
Kg/cm² and 70 Kg/cm² each, which controlled by hydraulic pressure gauge provided in the
specially designed tailstock attachment. Out of three sets of samples, one set used for tensile
test, one set for hardness test and other one set used for microscopic evaluation test. The test
results and findings are shown in the Table 4.1.1 to 4.1.3. Figure 4.1 is an image of friction
welded components of Carbon Steel (20C15) and Carbon Steel (20C15) welded with spindle
speed of 1210 RPM and 2040 RPM.

47
Table 4.1.1 – Measurements of parameters controlling the friction welding quality
Test
sample
No.
Spindle
speed
(RPM)
Initial
overall
length
of work
(mm)
Final
length
after
welding
(mm)
Burn off
length
(mm)
Max.
interface
temp
(ºC)
Frictional
time
(Sec)
Forge
Time
(Sec)
Frictional
Pressure
(Kg/cm²)
Forge
Pressure
(Kg/cm²)
1a 1210 600 577 23 538 16 10 40 70
1b 2040 600 576 24 549 12 11 40 70
2a 1210 200 190 10 516 25 8 40 70
2b 2040 200 189 11 528 11 8 40 70
3a 1210 200 192 9 523 26 7 40 70
3b 2040 200 190 10 536 13 8 40 70
4.1.2 Tensile test results
Samples 1a and 1b were taken for tensile test. A gauge length of 50mm was taken for
measuring the elongation. It is assumed that the elongation is proportional. The tensile test
was conducted on 30T Universal Testing Machine. The overall length of the tensile tested
sample was 577mm and 576mm each. The result as per Table 4.1.2 is obtained.
Table 4.1.2 –Tensile test results
Test
sample
No.
Spindle
speed
(RPM)
Length
of work
(mm)
Yield
Strength
(Kgf)
Breaking
load
(Kgf)
Ultimate
tensile
strength
(Kgf)
Elonga-
tion in
50mm
gauge
length
(mm)
Reduced
diameter
(mm)
Elonga-
tion
(%)
Reduc-
tion in
area
(%)
1a 1210 577 2300 2500 3150 3 8.4 6 29
1b 2040 576 3200 3500 4120 6 6.5 12 58
# Carbon Steel 3700 4100 4300 10.5 6.2 21 62
 Tensile tested samples 1a & 1b, fractured at welded joint.
# Tensile test results of bare carbon steel (20C15).

48
Tensile test results given the table 4.1.2 shows that, ultimate tensile strength of bare carbon
steel bar of 10mm diameter is 4300 Kgf (537 N/mm²); ultimate tensile strength of sample 1a,
is 3150 Kgf (393 N/mm²) and sample 1b, is 4120 Kgf (514 N/mm²) respectively.
It is found that, the sample 1b, welded with 2040 RPM spindle speed get 95% strength of
parent metal and sample 1a, welded with 1210 RPM spindle speed get 73% strength of parent
metal. The results of other mechanical properties are almost same as the ultimate tensile
strength.
Hence, this rotary friction welded combination is suitable for tensile and compressible load
applications.
4.1.3 Rockwell hardness test
Samples 2a and 2b were taken for hardness test. In order to find the Rockwell hardness of the
samples, 1.6mm ball indentor and load of 100 Kg is considered. There are three positions like,
joint (0mm), -5mm and +5mm were considered for taking hardness. The test results as per
Table 4.1.3 were obtained.
Table 4.1.3 –Rockwell hardness test results
Test
sample
No.
Spindle
speed
(RPM)
Rockwell Hardness Number
(HRB)
-5mm at joint +5mm
2a 1210 84 76 83
2b 2040 82 78 81
# Carbon Steel 86 -
# Test results of bare carbon steel (20C15)
It is found that, the friction welded sample 2b, welded with 2040 RPM spindle speed get 90%
hardness (78 HRB) of parent metal (86 HRB) at weld joint and friction welded sample 1a,
welded with 1210 RPM spindle speed get 88% hardness (76 HRB) of parent metal at weld
joint. It is assumed that if the friction welding is more precise, same hardness may be
obtained.

49
4.1.4 Microstructure Evaluation (SEM Test)
To know the micro-structural details like grain shape and size, morphology of inclusions and
precipitates, micro-segregation, micro-cracks, weld defects etc. in friction welded
components, SEM test were conducted. For this purpose JEOL make JSM-6390LV Scanning
Electron Microscope was used. Resulting micrographs are shown in the Fig. 4.2 given below.
In order to evaluate the microstructure at the weld region, the welded sample size is reduced
from 200mm length x 10mm diameter to 10mm length x 5mm diameter and made a polished
surface.
Samples 3a and 3b were taken for SEM test. There are three sets of images are obtained with
zoom size of 30X, 500X and 3000X.

50
Images of sample 3a, shows that there is an interface defect at one edge, which may be due
to incomplete bonding. The reason is that improper heating and short weld time, slow
speed, work piece preparation, etc. In the middle of interface, intermediate white colour
shows the microstructure of ferrite which is structure of hypo eutectoid steel. This improper
bonding can be controlled by optimization of weld parameters and proper work piece
preparation.
Images of sample 3b, shows that the weld joint is almost perfect. There is no crack or any
other imperfections seen in the weld interface. There is no intermetallic barrier between
weld joints. The reason for the perfect welding is that the weld was done at higher speed of
2040 RPM.
4.2 CARBON STEEL (20C15) – STAINLESS STEEL (SS 304)
Rotary friction welding between dissimilar combinations of Carbon Steel (20C15) and
Stainless Steel (SS 304) were done with spindle speed of 1210 RPM and 2040 RPM. For this
purpose, three sets of joints were made in each spindle speed. The length of the work piece
used for tensile test is 300mm each and other work piece length was 100mm each. Frictional
time and forge time was taken by using stop watch. By using infrared thermometer, weld
interface temperature was taken. Frictional pressure and forge pressure was taken as constant
of 40 Kg/cm² and 70 Kg/cm² each, which controlled by hydraulic pressure gauge provided in
the specially designed tailstock attachment.
Out of three sets of samples, one set used for tensile test, one set for hardness test and other
one set used for microscopic evaluation. The test results and findings are shown in the Table
4.2.1 to 4.2.3. Figure 4.3 is an image of friction welded components of Carbon Steel (20C15)
and Stainless Steel (SS304) welded with spindle speed of 1210 RPM and 2040 RPM.

51
Test
sample
No.
Spindle
speed
(RPM)
Initial
overall
length
of work
(mm)
Final
length
after
welding
(mm)
Burn off
length
(mm)
Max.
interface
temp
(ºC)
Frictional
time
(Sec)
Forge
Time
(Sec)
Frictional
Pressure
(Kg/cm²)
Forge
Pressure
(Kg/cm²)
1a 1210 600 593 7 518 15 8 40 70
1b 2040 600 594 6 528 14 7 40 70
2a 1210 200 192 8 518 17 7 40 70
2b 2040 200 191 9 535 13 6 40 70
3a 1210 200 190 10 522 16 7 40 70
3b 2040 200 189 11 526 14 6 40 70

52
Test
sample
No.
Spindle
speed
(RPM)
Length
of work
(mm)
Yield
Strength
(Kgf)
Breaking
load
(Kgf)
Ultimate
tensile
strength
(Kgf)
Elonga-
tion in
50mm
gauge
length
(mm)
Reduced
diameter
(mm)
Elonga-
tion
(%)
Reduc-
tion in
area
(%)
1a 1210 593 1000 1500 1750 1 9.9 2 0.1
1b 2040 594 1050 1500 1930 1 9.9 2 0.1
# Carbon Steel 3700 4100 4300 10.5 6.2 21 62
## Stainless Steel 2633 3975 4180 9.0 6.0 18 36
# Test results of bare Carbon Steel (20C15).
## Test results of bare Stainless Steel (SS 304).
Tensile test results given the Table 4.2.2 shows that, ultimate tensile strength of bare carbon
steel bar of 10mm diameter is 4300 Kgf (537 N/mm²) and stainless steel bar is 4180 Kgf (523
N/mm²); ultimate tensile strength of sample 1a, is 1750 Kgf (219 N/mm²) and sample 1b,
1930 Kgf (241 N/mm²) respectively.
It is found that, the sample 1b, welded with 2040 RPM spindle speed get only 46% strength of
bare SS 304 metal and sample 1a, welded with 1210 RPM spindle speed get only 42%
strength of bare SS 304 metal. The results of other mechanical properties are almost same as
the ultimate tensile strength.
Hence, this rotary friction welded combination not suitable for tensile load applications.

53
Test
sample
No.
Spindle
speed
(RPM)
(HRB)
-5mm at joint +5mm
2a 1210 85 73 91
2b 2040 85 74 91
# Carbon Steel 86 -
## Stainless Steel 92
# Test results of bare Carbon Steel (20C15)
## Test results of bare Stainless Steel (SS 304)
It is found that, the friction welded sample 2b, welded with 2040 RPM spindle speed get
86% hardness (74 HRB) of bare carbon steel (86 HRB) at weld joint and friction welded
sample 1a, welded with 1210 RPM spindle speed get 85% hardness (73 HRB) of bare
carbon steel at weld joint. There is only 15% less hardness than the parent metal having
lowest hardness.
To know the microstructural details like grain shape and size, morphology of inclusions and
surface.

54
Images of sample 3a, shows that there is an interface defect and crack at one edge, which
may be due to incomplete bonding and non-coalescence at the edge. The reason is that
improper heating and short weld time, slow speed, work piece preparation, etc. This
improper bonding and non-coalescence can be controlled by optimization of weld
parameters and proper work piece preparation. There are no other notable points.
other imperfections seen in the weld interface. There is mild intermetallic barriers are
formed at weld joint interface. Actually, this is not a perfect welded structure.

55
4.3 CARBON STEEL (20C15) – COPPER (C10300)
Rotary friction welding between dissimilar combinations of Carbon Steel (20C15) and Copper
(C10300) were done with spindle speed of 1210 RPM and 2040 RPM. For this purpose, three
sets of joints were made in each spindle speed. The length of the work piece used for tensile
test is 300mm each and other work piece length was 100mm each. Frictional time and forge
time was taken by using stop watch. By using infrared thermometer, weld interface
specially designed tailstock attachment.
4.3.1 to 4.3.3. Fig. 4.5 is an image of friction welded components of Carbon Steel (20C15)
and Copper (C10300) welded with spindle speed of 1210 RPM and 2040 RPM.

56
Test
sample
No.
Spindle
speed
(RPM)
Initial
overall
length
of work
(mm)
Final
length
after
welding
(mm)
Burn off
length
(mm)
Max.
interface
temp
(ºC)
Frictional
time
(Sec)
Forge
Time
(Sec)
Frictional
Pressure
(Kg/cm²)
Forge
Pressure
(Kg/cm²)
1a 1210 600 596 4 246 27 9 40 70
1b 2040 600 595 5 295 21 10 40 70
2a 1210 200 195 5 294 32 10 40 70
2b 2040 200 197 3 306 15 11 40 70
3a 1210 200 194 6 292 27 12 40 70
3b 2040 200 193 7 302 22 10 40 70
sample was 596mm and 595mm each. The result as per table 4.3.2 is obtained.
Test
sample
No.
Spindle
speed
(RPM)
Length
of work
(mm)
Yield
Strength
(Kgf)
Breaking
load
(Kgf)
Ultimate
tensile
strength
(Kgf)
Elonga-
tion in
50mm
gauge
length
(mm)
Reduced
diameter
(mm)
Elonga-
tion
(%)
Reduc-
tion in
area
(%)
1a 1210 596 - - 550 - - - -
1b 2040 595 - - 700 - - - -
# Carbon Steel 3700 4100 4300 10.5 6.2 21 62
## Copper 1626 2374 2650 6 5.9 12 34
## Test results of bare Copper (C10300).

57
steel bar of 10mm diameter is 4300 Kgf (537 N/mm²) and Copper bar is 2650 Kgf (331
N/mm²); ultimate tensile strength of sample 1a, is 550 Kgf (69 N/mm²) and sample 1b, 700
Kgf (88 N/mm²) respectively.
bare copper bar and sample 1a, welded with 1210 RPM spindle speed get only 21% strength
of bare copper bar. As the joint was broken during tensile test, other mechanical properties
could not be measured.
Hence, this rotary friction welded combinations are not suitable for tensile load applications.
This may be suitable for extension rod to the actuators, which requires only mild compressive
loads.
Test
sample
No.
Spindle
speed
(RPM)
(HRB)
-5mm at joint +5mm
2a 1210 85 41 46
2b 2040 83 42 47
# Carbon Steel 86 -
## Copper 48
## Test results of bare Copper (C10300)

58
87% hardness (42 HRB) of bare copper bar (48 HRB) at weld joint and friction welded
copper at weld joint. There is only 15% less hardness than the parent metal having lowest
hardness.
surface.

59
Images of sample 3a, shows that there is an interface barriers and ridges are formed, which
may be due to incomplete bonding and non-coalescence at the weld joint. The reason is that
sufficient temperature is not reached for the good inter metallic bonding. This improper
bonding cannot be controlled at certain extend. This is due to the variation in melting
temperature of carbon steel and copper. In addition that copper has very high thermal
conductivity than carbon steel. Hence constant temperature distribution is not possible.
other imperfections seen in the weld interface. There is mild inter-metallic barriers are
formed at weld joint interface. Actually, this is not a perfect welded structure.
This welded combination is not suitable for tensile load applications and only suitable for
mild compressive load applications.
4.4 CARBON STEEL (20C15) – ALUMINIUM ALLOY (6063)
Rotary friction welding between dissimilar combinations of Carbon Steel (20C15) and
Aluminium Alloy (6063) were done with spindle speed of 1210 RPM and 2040 RPM. For this
4.4.1 to 4.4.3. Fig. 4.7 is an image of friction welded components of Carbon Steel (20C15)
and Aluminium Alloy (6063) welded with spindle speed of 1210 RPM and 2040 RPM.

60
Test
sample
No.
Spindle
speed
(RPM)
Initial
overall
length
of work
(mm)
Final
length
after
welding
(mm)
Burn off
length
(mm)
Max.
interface
temp
(ºC)
Frictional
time
(Sec)
Forge
Time
(Sec)
Frictional
Pressure
(Kg/cm²)
Forge
Pressure
(Kg/cm²)
1a 1210 600 583 17 149 16 7 30 50
1b 2040 600 584 16 153 15 6 30 50
2a 1210 200 192 8 130 23 8 30 50
2b 2040 200 189 11 151 19 7 30 50
3a 1210 200 186 14 146 21 8 30 50
3b 2040 200 184 16 152 18 7 30 50

61
Test
sample
No.
Spindle
speed
(RPM)
Length
of work
(mm)
Yield
Strength
(Kgf)
Breaking
load
(Kgf)
Ultimate
tensile
strength
(Kgf)
Elonga-
tion in
50mm
gauge
length
(mm)
Reduced
diameter
(mm)
Elonga-
tion
(%)
Reduc-
tion in
area
(%)
1a 1210 583 - - 580 - - - -
1b 2040 584 - - 620 - - - -
# Carbon Steel 3700 4100 4300 10.5 6.2 21 62
## Aluminium 1562 1886 2050 12 5.9 24 35
## Test results of bare Aluminium Alloy (6063).
steel bar of 10mm diameter is 4300 Kgf (537 N/mm²) and Aluminium Alloy bar is 2050 Kgf
(256 N/mm²); ultimate tensile strength of sample 1a, is 580 Kgf (72 N/mm²) and sample 1b,
620 Kgf (77 N/mm²) respectively.
bare aluminium bar and sample 1a, welded with 1210 RPM spindle speed get only 28%
strength of bare aluminium bar. As the joint was broken during tensile test, other mechanical
properties could not be measured.
Hence, this rotary friction welded combinations are not suitable for tensile load applications.
This may be suitable for stationary and mild compressive load applications.

62
Table 4.4.3 – Rockwell hardness test results
Test
sample
No.
Spindle
speed
(RPM)
(HRB)
-5mm at joint +5mm
2a 1210 83 25 34
2b 2040 85 27 35
# Carbon Steel 86 -
## Aluminium 37
## Test results of bare Aluminium Alloy (6063)
73% hardness (27 HRB) of bare aluminium bar (37 HRB) at weld joint and friction welded
aluminium at weld joint. There is only 27% less hardness than the parent metal having
lowest hardness.
When the time of preparation of samples for microstructure evaluation test (SEM Test);
during machining operation, as the joint was very weak, it was broken. So, could not prepare
the test sample. Hence, could not conduct a SEM test to this sample.

63
4.5 STAINLESS STEEL (SS 304) – STAINLESS STEEL (SS 304)
Rotary friction welding between similar combinations of Stainless Steel (SS 304) and
Stainless Steel (SS 304) were done with spindle speed of 1210 RPM and 2040 RPM. For this
one set used for microscopic evaluation. The test results and findings are shown in the table
4.5.1 to 4.5.3. Fig. 4.8 is an image of friction welded components of Stainless Steel (SS304)
and Stainless Steel (SS304) welded with spindle speed of 1210 RPM and 2040 RPM.

64
Test
sample
No.
Spindle
speed
(RPM)
Initial
overall
length
of work
(mm)
Final
length
after
welding
(mm)
Burn off
length
(mm)
Max.
interface
temp
(ºC)
Frictional
time
(Sec)
Forge
Time
(Sec)
Frictional
Pressure
(Kg/cm²)
Forge
Pressure
(Kg/cm²)
1a 1210 600 592 8 540 30 12 40 70
1b 2040 600 593 7 549 28 11 40 70
2a 1210 200 196 4 528 22 10 40 70
2b 2040 200 195 5 535 17 9 40 70
3a 1210 200 194 6 532 24 11 40 70
3b 2040 200 192 8 542 19 10 40 70
Test
sample
No.
Spindle
speed
(RPM)
Length
of work
(mm)
Yield
Strength
(Kgf)
Breaking
load
(Kgf)
Ultimate
tensile
strength
(Kgf)
Elonga-
tion in
50mm
gauge
length
(mm)
Reduced
diameter
(mm)
Elonga-
tion
(%)
Reduc-
tion in
area
(%)
1a 1210 592 - 1400 1650 1 9.9 2 2
1b 2040 593 - 1600 1800 2 9.8 4 4
# Stainless Steel 2633 3975 4180 9.0 6.0 18 36
# Test results of bare Stainless Steel (SS 304).

65
Tensile test results given the Table 4.5.2 shows that, ultimate tensile strength of bare stainless
steel bar is 4180 Kgf (523 N/mm²); ultimate tensile strength of sample 1a, is 1650 Kgf (206
N/mm²) and sample 1b, 1800 Kgf (225 N/mm²) respectively.
bare SS 304 metal and sample 1a, welded with 1210 RPM spindle speed get only 39%
strength of bare SS 304 metal. The results of other mechanical properties are almost same as
the ultimate tensile strength.
Hence, this rotary friction welded combination not suitable for tensile load applications.
Test
sample
No.
Spindle
speed
(RPM)
(HRB)
-5mm at joint +5mm
2a 1210 79 77 80
2b 2040 88 86 89
# Stainless Steel 92
# Test results of bare Stainless Steel (SS 304)
93% hardness (86 HRB) of bare stainless steel (92 HRB) at weld joint and friction welded
stainless steel at weld joint. There is only 16% less hardness than the parent metal.

66
surface.
Images of sample 3a, shows that there is no noticeable weld defects or cracks in the joint
interface.
other imperfections seen in the weld interface.

67
4.6 COPPER (C10300) – COPPER (C10300)
Rotary friction welding between similar combinations of Copper (C10300) and Copper
(C10300) were done with spindle speed of 1210 RPM and 2040 RPM. For this purpose, three
sets of joints were made in each spindle speed. The length of the work piece used for tensile
test is 300mm each and other work piece length was 100mm each. Frictional time and forge
time was taken by using stop watch. By using infrared thermometer, weld interface
specially designed tailstock attachment.
one set used for microscopic evaluation. The test results and findings are shown in the table
4.6.1 to 4.6.3. Fig. 4.10 is an image of friction welded components of Copper (C10300) and
Copper (C10300) welded with spindle speed of 1210 RPM and 2040 RPM.

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