International Journal of Engineering Trends and Technology (IJETT) – Volume 27 Number 5 - September 2015
An overview over Friction Stir. Welding
Umasankar Das1, Dr. Vijay Toppo *2,
1
Research Scholar, Department of Manufacturing Engineering
National Institute of Foundry and Forge Technology, Hatia , Ranchi, India
2
Associate Professor, Department of Manufacturing Engineering
National Institute of Foundry and Forge Technology, Hatia , Ranchi, India
Abstract - Through this paper an attempt is made to
study and review a special welding technology of
friction stir welding (FSW) which is a solid-state
joining process. Friction Stir Welding (FSW) is a
recent advanced technique, invented by The Welding
Institute
(TWI) in 1991, that utilizes a nonconsumable rotating welding tool to generate
frictional heat and plastic deformation at the welding
location; thereby, affecting the formation of a joint
while the material is in the solid state. In particular,
FSW can be used to join high-strength aerospace
aluminum alloys and other high temperature metallic
alloys that are difficult to weld by conventional fusion
welding method. FSW is considered to be the most
significant development in metal joining process in a
decade The comprehensive body of knowledge that
has built up with respect to the friction stir welding
(FSW) of aluminum alloys. This study addresses the
current state of understanding and development of the
FSW process. The principles of weld formation,
welding parameters, design principles, including
metal flow and thermal history, before discussing how
process parameters affect the weld microstructure and
the likelihood of defects. and application areas of
FSW for improved welding are discussed The major
applications of FSW in the field of aerospace,
shipbuilding and automotive are also discussed with
reference to the several technical reports from FSW
machine manufacturers
Keywords — Friction stir welding, metal flow,
process
parameters,
mechanical
properties,
Microstructure
rapid and high quality welds of 2xxx and 7xxx series
alloys, traditionally considered unweldable, are now
possible. In FSW, a cylindrical shouldered tool with
a profiled pin is rotated and plunged into the joint area
between two pieces of sheet or plate material. as
shown in fig.1 The parts have to be securely clamped
to prevent the joint faces from being forced apart.
Frictional heat between the wear resistant welding tool
and the work-pieces causes the latter to soften without
reaching melting point, allowing the tool to traverse
along the weld line. The plasticized material,
transferred to the trailing edge of the tool pin, is
forged through intimate contact with the tool shoulder
and pin profile. On cooling, a solid phase bond is
created between the work-pieces. Friction Stir
Welding can be used to join aluminum sheets and
plates without filler wire or shielding gas. Material
thicknesses ranging from 0.5 to 65 mm can be welded
from one side at full penetration, without porosity or
internal voids. In terms of materials, the focus has
traditionally been on non-ferrous alloys, but recent
advances have challenged this assumption, enabling
FSW to be applied to a broad range of materials. [3]
The pieces are rigidly clamped onto a backing plate in
a manner that prevents the butting joint faces from
being forced apart. Frictional heat is generated
between the tool shoulder and the material of the work
pieces. This heat causes the latter to reach a viscoplastic state that allows traversing of the tool along the
weld line. The plasticized material is transferred from
the leading edge of the tool to the trailing edge of the
tool probe and is forged by the intimate contact of the
tool shoulder and the pin profile. It leaves a solid
phase bond between the two pieces. [1]
I .INTRODUCTION
Due to the affinity of aluminium for oxygen, it
cannot successfully be arc welded in an air
environment. In case of fusion welding in a normal
atmosphere oxidisation readily occurs as a result
both slag inclusion and porosity in the weld, greatly
reducing its strength. To overcome these problems
Friction stir welding (FSW). has been to use for
welding of aluminium alloy. [1] The Friction stir
welding (FSW) was invented and patented by W. M
Thomas et al. of the Welding Institute in Cambridge,
UK in December 1991.[2] Friction Stir Welding is a
solid-state process, which means that the objects are
joined without reaching melting point. This opens up
whole new areas in welding technology. Using FSW,
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Fig[1]. Process principles for friction stir welding.
The rotating non-consumable pin-shaped tool
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International Journal of Engineering Trends and Technology (IJETT) – Volume 27 Number 5 - September 2015
penetrates the material and generates frictional heat,
softening the material and enabling the weld [4]
II. LITERATURE REVIEW
A. Terminology.
To understand the process of friction stir welding
and the focus of this review is to define certain
terminologies and their usage in this process. In FSW,
the tool typically consists of a cylindrical shoulder
with a profiled probe, also called the pin. The material
or materials being welded can be called the work piece,
part, sample, or plate. The joint where the samples are
a butted will be referred to as the weld line. The part
used to support and clamp the sample is called the
backing plate, backing bar, or anvil. The tool rotates
at an angular velocity given in revolutions per minute
(RPM), which will be referred to as rotational speed
(RS). The translational velocity at which the tool
travels along the weld line is called the feed rate or
travel speed (TS), and will be given in millimetre per
second (mm/s) or inches per minute. The side of the
weld where the angular velocity and forward velocity
of the pin tool are additive is called the advancing or
leading side. The other side where the angular velocity
and translational velocity are in opposite directions is
called the trailing or retreating side. As shown in
Figure 2, forces act in three dimensional spaces. The
force along the X-axis, Y-axis, and Z-axis will be
referred to as the translational (Fx), transverse (Fy),
and axial force (Fz) respectively, and will be given in
Newton‟s (N). The moment (Mz) about the axis of
rotation will be referred to as the torque and given in
Newton-meters (N-m). Power however will be given
in Watts (N-m/s). Figure 2 &3 shows a schematic of
the process and with the given terminologies.[5]
Fig.[2]: Schematic Diagram of FSW
In FSW a cylindrical-shouldered tool, a
cylindrical/profiled, threaded/unthreaded probe (pin)
is rotated at a constant speed and moved at a constant
traverse rate in the joint line between two pieces of
sheet or plate material, which are butt welded together
as shown in Fig 3. The parts have to be clamped
rigidly onto a backing plate in order to prevent the
abutting joint faces from being forced apart but also to
support the high plunging forces applied by the FSW
machine head. The length of the pin is slightly less
than the required weld depth and the tool shoulder
should be in direct contact with the surface of the
ISSN: 2231-5381
work piece. The probe is submerged into the work
piece and then the tool is moved along the weld line
with a tilt angle of 2-4 degrees increasing the pressure
under the tool shoulder.
Fig.[3]: Schematic Diagram of FSW
Frictional heat is generated between the wear-resistant
welding tool shoulder and pin on one side, and the
material of the work pieces on the other. This heat,
along with the heat generated by the plastic dissipation
due to the mixing process, causes the stirred materials
to soften without reaching the melting point (hence
cited a solid-state process), allowing the traversing of
the tool along the weld line in a plasticised tubular
shaft of metal. As the pin is moved in the direction of
welding, the leading face of the pin, often assisted by
a special pin probe, forces plasticised material to the
back of the pin while applying a substantial forging
force to consolidate the weld metal. The welding of
the material is facilitated by severe plastic deformation
in the solid state, involving dynamic re-crystallization
of the weld nugget [6&7]
Fig.[4]:(a) An FSW weld between aluminium
sheets (Nandan et al. 2008). (b) An actual tool, with a
threaded-pin (Nandan et al. 2008).[8]
The solid-state nature of the FSW process, in
combination with its unusual tool and asymmetric
nature, results in a very characteristic microstructure.
While some regions are common to all forms of
welding some are unique to the FSW process. Fig. [5]
shows A typical cross-section of the FSW joint
consists of a number of zones [9]
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International Journal of Engineering Trends and Technology (IJETT) – Volume 27 Number 5 - September 2015
Fig.[5]: Schematic cross–section of a typical FSW
weld showing four distinct zones: (A) base metal, (B)
heat–affected, (C) thermo-mechanically affected and
(D) stirred (nugget) zone [3].
The stir zone (also nugget, dynamically recrystallised zone), „D‟ in Fig.[5], is a region of
heavily deformed material that roughly
corresponds to the location of the pin during
welding. The grains within the stir zone are
roughly equiaxed and often an order of magnitude
smaller than the grains in the parent material
(Murr et al., 1997)[10]. A unique feature of the
stir zone is the common occurrence of several
concentric rings which has been referred to as an
onion-ring structure. The precise origin of these
rings has not been firmly established, although
variations in particle number density, grain size
and texture have all been suggested. The flow arm
is on the upper surface of the weld and consists of
material that is dragged by the shoulder from the
retreating side of the weld, around the rear of the
tool, and deposited on the advancing side of the
weld.
The thermo-mechanically affected zone (TMAZ),
„C‟ in Fig.[5], is situated on either side of the stir
zone. In this region the strain and temperature are
lower than in the stir zone and the effect of
welding on the microstructure is correspondingly
smaller. Unlike the stir zone the microstructure is
recognizably that of the parent material, even
though significantly deformed and rotated.
Although the term TMAZ technically refers to the
entire deformed region it is often used to describe
any region not already covered by the terms stir
zone and flow arm.
The heat-affected zone (HAZ), „B‟ in Fig.[5], is
common to all welding processes. As indicated by
the name, this region is subjected to a thermal
cycle but is not deformed during welding. The
temperatures are lower than those in the TMAZ
but may still have a significant effect if the
microstructure is thermally unstable. In fact, in
age-hardened aluminium alloys this region
commonly exhibits the poorest mechanical
properties.
The un affected zone or parent metal zone is „A‟,
which is remote from weld, not deformed, may
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have a thermal cycle from weld, not affected by
heat in terms of microstructure and mechanical
properties.[9]
The examination of many friction stir welds in
aluminum alloys has revealed that there are four
major microstructural zones, as indicated in Fig.
6.[11]
Fig. 6. Typical features of all different zones in a weld
cross-section of 6061-Al alloy: (a) Weld appearance
(b) Weld cross-section; (c) Cross-section around the
pin; (d) Grains in the nugget zone; (e) Grains in
TMAZ, (f) Grains in HAZ.
A number of potential advantages of FSW over
conventional fusion-welding processes can be
summarized as below:[12]
1) Good mechanical properties can achieved in
the as welded condition
2) Improved safety due to the absence of toxic
fumes or the spatter of molten material.
3) No consumables , conventional steel tools
can weld over 1000 m of aluminium and no
filler or gas shield is required for aluminium.
4) Easily automated on simple milling machines
with lower setup costs and less training.
5) Can operate in all positions (horizontal,
vertical, etc.), as there is no weld pool.
6) Generally good weld appearance and
minimal thickness under/over-matching, thus
reducing the need for expensive machining
after welding.
7) Low environmental impact.
However, some disadvantages of the process
can be listed below:
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International Journal of Engineering Trends and Technology (IJETT) – Volume 27 Number 5 - September 2015
1) Exit hole left when tool is withdrawn.
2) The single pass welding speeds in some sheet
alloys are slower than for some mechanised arc
welding techniques (although to date
experimental single pass welds 40mm deep
have been made by FSW)
3) The parts must be rigidly clamped against a
backing bar, to prevent weld metal breakout, if
full penetration welds are required (it may be
possible to overcome this problem in the future
if a bobbin tool concept under investigation can
be perfected).
4) Run-on/run-off plates are necessary where
continuous welds are required from one edge of
a plate to the other
5) Due to work piece clamping and access
requirements, applications where portable
equipment could be used may be limited.
6) Large down forces required with heavy-duty
clamping necessary to hold the plates together.
7) Less flexible than manual and arc processes
(difficulties with thickness variations and nonlinear welds).
8) Often slower traverse rate than some fusion
welding techniques although this may be offset
if fewer welding passes are required.
B. Welding Materials
A wide range of materials can be successfully joined.
These materials include thermoplastics, lead, Zinc,
Aluminum alloys, Copper, Silver and Gold. Materials
with higher melting points (in excess of 1100°C) such
as ferrous metals and alloys can also be joined.
However they require probes of high grade
temperature resisting materials such as tungsten [2].
Aluminum has been welded in single passes ranging
from 0.050”or 1.27 ≈ 1 mm to 2” 0r 50 mm in
thickness. Using a double pass method, welds up to 4”
or 100 mm thick have been made. Copper up to 2” or
50 mm thick has been welded. Welds up to 0.5” or 12
mm thick have been successfully made in steel using
the double pass method, and 0.37” or 9-10 mm thick
magnesium alloy AZ61A has been welded in a single
pass [5]. Friction stir welding has successfully been
performed in a variety of joint geometries. Butt welds,
corner welds, T-sections, overlap welds, and fillet
welds have all been done [2]. Circumferential welds
have also been performed in the aerospace industry for
the manufacture of large cryogenic tanks [13].
Common weld able materials are 1. Aluminum (all
alloys), 2. Copper, 3. Brass, 4. Magnesium, 5.
Titanium, 6. Steel Alloys, 7. Stainless Steel, 8. .
Nickel and 9. Lead [14]
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Why Aluminium Alloys
Steel for FSW.?[ 15]
selected over the
Aluminium Alloys are soft, durable,
lightweight, ductile and malleable metal
compare to steel.
Some aluminum alloys are stronger
than steel.
Lighter & Stiffer compared to steel.
Less corrosive than steel.
C. Welding Tools
A FSW tool may be made out of a number of different
materials. Choice of a material for a tool is dependent
on the type of metal material to be welded,
particularly the melting temperature of the material.
An additional consideration is the desired travel speed.
The tool has two basic parts; the shoulder and pin. The
tool shoulder has two general functions, create
frictional heat at the tool/work piece interface and to
cap the plasticized material as it “stirred”. The pin is a
cylindrical pin projecting from the distal shoulder
surface and has a longitudinal axis co-extensive with
the shoulder longitudinal axis. The pin must be large
enough to stay above the plastic stress level at
operating temperatures. Current FSW practice uses a
pin having a surface profile consistent with the thread
of a bolt, much like the end of a machine bolt [16].
The purpose of profiling the pin is to reduce traverse
loads and improve material flow [17]. Tool pin shapes
have taken the form of frusto-conical, inverted frustoconical, spherical, and pear shape, to simple conical,
truncated cones, to slightly tapered cylinders [17,18].
Cocks et al. introduced a pin which has a combined
right handed and left handed thread pattern. This
“enantionmorphic” pin is said to produce welds of
improved mechanical properties [19] There are
several tool materials that have been used in the
FSW/P process. These materials include but are not
limited to; tool steels , high speed steel (HSS), Nialloys, metal carbides and ceramics.
According to
Meilinger and Torok [20] and Zhang et al. [21], the
characteristics that have to be considered in choosing
the tool material for FSW/P includes
 Resistance to wear,
 No harmful reactions with the weld metal,
 Good strength, dimensional stability and creep
resistance at ambient and elevated temperature,
 Good thermal fatigue strength to resist repeated
thermal cycles,
 Good fracture toughness to resist the damage
during plunging and dwelling,
 Low coefficient of thermal expansion, and Good
machinability for the manufacture of complex
features on the shoulder and probe
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Table.1: FSW parameters and tool materials
for FSW of steels
Materials to be
welded
Plate
thickn
ess
(mm)
Tool
rotation
rate
(rpm)
Tool
traverse
speed
(mm/min)
Tool materials
Refer
ences
SK5
IF steel,
S12C, S35C
4
1.6
700
400
80
100–400
WC-Co
WC
[22]
[23]
AISI 1018
steel
AISI 409M
ferritic
stainless steel
5
1000
50
[24]
4
8001200
30-110
tungsten
based alloy
tungsten
based alloy
M190
martensitic
steel
1
1000
12.6 –
101.4
[26]
ASTM A945
9.5
300-600
51-203
304L, 316L
5, 10
300–700
150, 180
composite
toolDENSIMET180 & CY-16
PCBN
(polycrystalli
ne cubic
boron
nitride).
W
HSLA-65
400–450
99–120
W
[29]
DH-36
6.4,
12.7
6.4
W alloy
[30]
6.4
-
102–457
C–Mn
-
Polycrystallin
e cubic boron
nitride
[31]
12% Cr steel
12
-
240
-
[32]
AISI 1010
6.4
450–650
25–102
304L
300, 500
102
304
3.2,
6.4
6.0
Mo and Wbased alloys
W alloy
550
78
[33,3
4]
[35,3
6]
[37]
304
6.0
550
78
Polycrystallin
e cubic boron
Polycrystallin
e cubic boron
[25]
[27]
[28]
Table 2: Selection of tools designed in TWI
[38]
D. Tool Design
FSW tool design, which includes
material selection and geometry, is one of the
most important factors that influence heat
generation, plastic flow, joint integrity, the
resulting microstructure and the mechanical
properties. Tool materials, apart from having to
satisfactorily endure the welding process, affect
friction coefficients and heat generation. Tool
configuration influences joint size and profile
[39,40]. Selecting the correct tool material
requires the knowledge of material characteristics
that are important for each friction stir
application. In addition to the physical properties
of a material, some practical considerations such
as wear resistance, reactivity and machineability
are properties that may also dictate the tool
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material selection[41]. Hot-worked tool steel,
such as AISI H13 has proven acceptable for
welding a wide range of materials because it
provides sufficient hardness, is easily available, has
good machine ability, is relatively cheap and has
high abrasion resistance[42,43]. Other types of
materials that are commonly used in the manufacture
of tools include: nickel alloys, tungsten alloys, and
Polycrystalline Cubic Boron Nitride (PCBN)[44].
The tool geometry is concerned with the shape and
size of the pin and shoulder. From the heating
aspect, the relative sizes of the pin and shoulder are
important; the shoulder also provides confinement
for the heated volume of material. A concave
shoulder profile is usually employed; it acts as an
escape volume for the material displaced by
cylindrical pins, and prevents material from
extruding out of the sides of the shoulder. The
diameter of the tool‟s shoulder is proportional to the
torque at a constant rotational speed. As the tool
shoulder diameter increases, so does the torque
during welding. Different pin diameters have
virtually no effect on torque values. Increasing the
diameter of the shoulder has practical limitations,
and tends to produce side flash on the weld surface
With increasing experience and improvement in
understanding material flow, the tool geometry has
evolved significantly. The pin length is typically
slightly shorter than the thickness of the work piece,
and its diameter is typically slightly larger than the
thickness of the work piece [45,46]. Table 2. gives a
selection of tools designed at TWI with their
corresponding applications.
E. Variables affecting in Friction Stir Welding [47]
Complex material movement and plastic
deformation involves in FSW Welding parameters
such as tool geometry, and joint design exert
significant effect on the material flow pattern and
temperature distribution, which influence the
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International Journal of Engineering Trends and Technology (IJETT) – Volume 27 Number 5 - September 2015
micro structural evolution of material.. The strength
of friction stir welding depends on the following
three main process parameters. They are;
1. Shoulder diameter :- Generates heat, grip
plasticized material and establish material
flow field.
2. Tool rotational speed :- Mixing of material,
breaking of oxide layer, generates some
amount of frictional heat
3.Travel speed :- Controls weld appearance,
Heat Control
4. Downward Force :- Frictional Heat,
Maintain Contact b/w tool shoulder & work
piece
5. Depth of penetration- Flow of plasticized
materials and weld properties
6 .Tilting angle -The appearance of weld
F .. Factors Affecting Weld Quality[47]
o
Deformation characteristics of the
metal ,
o
Angle of tool
o
Traversing speed of the tool
o
Spinning speed of tool
o
Pressure applied by the pin tool
Table.3: Selection of process parameters[25]
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G. Metal transfer modes in FSW method
The material flow visualization during friction stir
welding is the key to understand the internal
workings of the process and is critical to process
modelling. Improved geometry of the tool can give a
good weld. Complex geometry namely triflute has
been performed in a lap joint which gave a better weld
formation than simple geometry. The flow of material
has been found to be more at the bottom of the
shoulder and the pin .stirring action is more effective
than the simple geometry [48]. Fig.7 (a) shows a
simple geometry where the flow is limited where as in
complex geometry (triflute) the flow patterns are more
crowded at the shoulder and pin as shown in the Fig.7
(b). First mode of metal transfer is by shoulder while
the second mode of metal transfer is due to pin. When
the tool rotates the shoulder touches the work piece,
by which friction heat is produced and plastic
deformation occurs at the weld zone [49]. When the
material flow goes around the region of the shoulder
and pin, the compaction of material is mainly due to
the shoulder and it influences the first mode of metal
transfer. This will eliminate the formation of defect in
weld zone, then its tensile property increases.[50].
Extrusion of metal flow has been influenced by the
stirring action of the pin. Layer by layer material flow
takes place at the top region while onion ring pattern
has been observed below the layers as shown in the
Fig.8 [51]. First mode of metal transfer has been
influenced by the movement of material from the
advancing side to retreating side for every rotation of
tool leading to the formation of layers one below the
other. Second mode of metal transfer is a combined
effect of both material flow layer by layer and
extrusion of material in plasticized condition [49, 50].
When macro structural observation on the specimen
has been carried out perpendicular to the weld
direction concentric ring patterns were observed. The
structure resembles the onion ring pattern and hence
the mechanism of flow patter is named as “onion ring”.
The combined effect of two modes of metal transfer
results to produce the onion rings [51, 53]. The
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International Journal of Engineering Trends and Technology (IJETT) – Volume 27 Number 5 - September 2015
extrusion of material at each rotation of the tool pin
and compaction of shoulder together creates the
geometry of onion rings [54,55] as shown in the Fig.9.
Two modes of metal transfer are responsible for the
formation of onion rings [51-55]. Arbegast.et.al
suggested five conventional FSW working zones
namely preheat zone, initial deformation zone,
extrusion zone, forging zone, and post heat/cool down
zone [52] as depicted in the Fig.10(a)&(b). The term
pre heat itself denotes heating to prier condition and
here it is the region of neighbour near to the edge of
the shoulder circumference. As the friction heat is
developed by the shoulder some amount of heat is
transferred along the welding direction, which is a pre
heat condition for the weld to progress. Based on the
traverse speed and weld metal thermal property the
amount of pre heat prevails. In the initial deformation
zone the material is heated to plastic deformation
stage. The material flow is influenced at the shoulder
bottom and pin. Extrusion zone is due to the stirring
action of the pin. The material is stirred from the
advancing side to the retreating side. Depending on
the stress concentration around the pin and
temperature distribution, the width of the extrusion
zone varies. In the forging zone the material from both
sides are mixed well at plastic deformation condition.
Based on the feed rate and rotating speed the effect of
extrusion is followed by this zone. The final zone is
the cooling after forged zone, in which the stirred
material is made to set in a well mixed state. The
tensile property of the weld is influenced based on the
cooling rate. During the rotation of the tool the
velocity will be high near the tool shoulder edge and
then it gradually decreases to the layer below. Thus
the compaction created by the shoulder and extrusion
of pin is responsible for the formation of onion rings
Fig.8: Schematic representation of two
modes of metal transfer [51]
Fig.9: Schematic representation of onion ring
pattern [54]
Fig.10 (a) Schematic representation of
material flow (b) FSW metal working zones
[52]
o
o
o
o
o
Fig. 7: Flow pattern of a (a) simple geometry
(b) complex geometry [48]
o
o
o
o
o
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III. Advantages of FSW amongst others (56)
Friction stir welding is environmentally friendly
process as it does not generate fumes, gases or
smoke.
 Friction stir welding is suitable for quantities
ranging from prototype to high production.
 As friction stir welding is a solid state process,
possibility of porosity and slag inclusions are
eliminated.
 Welding of unequal cross sections can be done
by friction stir welding process.
 It allows choosing of either manual loading or
optional automated loading.
 Dissimilar materials which are normally not
compatible for welding can be friction stir
welded.
 Friction stir welding is consistent and repetitive
process.
 It consumes low energy and low welding
stress.
 It reduces raw material cost with bi-metal
applications.
 It reduces maintenance cost.
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International Journal of Engineering Trends and Technology (IJETT) – Volume 27 Number 5 - September 2015
o
o
o
o
o
o
o
o
o
o
 It reduces machining labor, which in turn
increases capacity and reduces perishable tooling
cost.
 It reduces cost for complex forgings or
castings.
 Self-cleaning action of friction stir welding
reduces or eliminates surface preparation cost or
time for some material combinations.
 In case of friction stir welding, joint strength is
equal to or greater than parent material.
 It creates a narrow heat affected zone.
 It has accurate control over post welds
tolerances.
 It is highly precision and repeatable process.
 No flux or filler metals or gases are required in
case of friction welding.
 Create cast or forge like blanks, without the
expensive costs of tooling and the minimum
quantity requirements.
 Friction stir welded joint can withstand high
temperature variation.
IV. Applications [14]
The current industries which utilize FSW are the
aerospace,
railway,
land
transportation,
shipbuilding/marine, and the construction industries.
These industries have seen a push towards using
lightweight yet strong metals such as aluminium. In
Aerospace Industry the FSW can be considered for
following uses
 Wings, fuselages, empennages
 Cryogenic fuel tanks for space vehicles
 Aviation fuel tanks
 External throw away tanks for military aircraft
 Military and scientific rockets
 Repair of faulty MIG welds
 Locomotive train and carriage panels (aluminium)
 Aircraft fuselage and avionics development
 Truck bodies, caravans and space frames
 Heat sinks and electronics enclosures
 Boat and ship panel sections
 Flat and cylindrical fuel tanks and bulk liquid
containers
 Aluminium bridge sections, architectural
structures and frames
 Pipelines and heat exchangers
 Electrical motor housings
In Railway Industry the commercial applications
include:
 High speed trains
 Rolling stock of railways, underground carriages,
trams
 Railwaytankers and goods wagons
 Container bodies
In Land
Transportation
industry the
applications include
1. Engine and chassis cradles 2. Wheel rims 3.
Attachments to hydro formed tubes 4. Space
frames, e.g. welding extruded tubes to cast
nodes 5. Truck bodies & tail lifts for lorries 6.
ISSN: 2231-5381
Mobile cranes 7. Armour plate vehicles 8. Fuel
tankers 9. Caravans 10. Buses and airfield
transportation vehicles
2. In
shipbuilding and marine industries the
applications include
o Panels for decks, sides, bulkheads and floors
 Hulls and superstructures
 Helicopter landing platforms
 Marine and transport structures
 Masts and booms, e.g. for sailing boats
. Refrigeration plant
V.EXPERIMENTAL PROCEDURE [15]
Equipment used for Friction Stir Welding: may be a
Vertical Milling Machine, then arrange following
materials for the experiment.
1 .Selection of working material .2. Preparation of
tool, .3. Clamps/Fixture design: 4.Back plate .5
Setting of Tool, Fixture and Plates:
5.6. Considerations for
Friction Stir welding
Procedure : Input parameters or Independent Variables
considered: i) Rotational speed (N) in rpm, ii) Translation speed
(v) in mm/min, iii) Axial Force (F) in KN,
 Tool Profile to be considered:i) Cylindrical Pin.
 Working materials to be considered: - say AlAlloys
 Output parameters considered: i) Mechancal Properties- Tensile strength. ,hardness,
impact strength,
 Optimizing Methods considered: i) Taguchi Method ii) Anova Method
VI. Heat transfer calculation in FSW.[57]
6.1 Kinematic assumption.
The heat generated at the pin is approximately two
percent (2%) of the total heat so therefore heat
transfer at tool pin is ignored. Heat generation from
the shoulder surface is considered.
The heat generation from the shoulder surface can be
found from using eq.1
dQ = ω r dF = ω r2 τ contact
dθ·dr ….eq.no.1
Where r is the distance from the considered area to the
center of rotation, ω is the angular velocity, and r·d
and dr are the segment dimensions. Integration of Eq.
(1) over the shoulder area from Rps to R shoulder
gives the shoulder heat generation Q1.
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International Journal of Engineering Trends and Technology (IJETT) – Volume 27 Number 5 - September 2015
Boundary condition for calculation:
(a) Tool shoulder/work piece interface: - The heat
flux boundary condition for the work piece at the
tool shoulder and work piece interface is written
as
automotive applications which are also discussed in
this paper. From industrial perspectives, FSW process
is very competitive as it saves energy, has higher
tensile strength and prevents the joints from fusion
related defects
References:
1.
(b) Tool pin/work piece interface: - The heat flux
boundary condition at the tool pin and work piece
interface is similar to the tool shoulder/work piece
interface, and can be written as
(C) The convection boundary conditions: - The
convection boundary condition for all the work piece
surfaces exposed to the air can be written as
2.
3.
4.
5.
6.
7.
Where n is the normal direction vector of boundary
and h is the convection coefficient. The surface of the
work piece in contact with the backup plate is
simplified to the convection condition with an
effective convection coefficient.
8.
VII. CONCLUSION
Friction stir welding (FSW) is a solid-state joining
process based on the simple concept of heat
generation due to friction. Friction stir welding is used
for joining of two plates which are applied
compressive force by using fixtures over the work
table. Process parameter includes tool geometry, joint
design and welding parameters which are to be kept in
mind which performing FSW. After review on
previous work based, we come to the conclusion that
FSW opens a new welding area. FSW successfully
applied to wide variety of ferrous and non ferrous
alloys. Weld. Properties looks good in most cases. .
Low distortion, no spatter, no fumes achieved.
Welding will be done below the melting point of
metals
and
alloys.
Good
strength
is
possible. .Reasonable elongation. & Tool life is high
enough for high-value applications, . Good forging
action can achieved by tool.. . Further investigations
on the forces generated during single and multiple
passes for different alloys at different conditions and
for different process parameters might be very
beneficial The amount of heat generated between the
shoulder and the work piece during friction stir
processing dictates the quality of the processed zone.
It is an alternative to fusion welding. This technology
is need and requirement as far as present scenario is
concerned. The importance of friction stir welding is
reported by several authors. For this reason now
friction stir welding is adopted for several major
applications . The major application of FSW process
includes the field of aerospace, shipbuilding and
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