Friction stir welding is used to join aluminum alloy AA6061 reinforced with 6% Al2O3 particles. Tests on welded specimens showed that ultimate tensile strength was highest at a tool rotation speed of 1100 rpm, while breaking stress and elongation were also highest. Hardness was lowest at this speed, resulting in the best overall joint efficiency. Microstructure, mechanical properties, and welding parameters were analyzed to characterize the friction stir welded aluminum metal matrix composite.

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FRICTION STIR WELDING OF ALUMINIUM
METAL MATRIX COMPOSITE
Himansu Sekhar Sahu(U13ME086), Mohammad jawed rain(U13ME123) , Narendra
Gautam(U13ME134), Navneet Nishant (U13ME136), Pritam Sankar Dhupal(U13ME150)
Mrs.G.Sucharitha, M.Tech, Assistant Professor, Bharath University, Chennai.
ABSTRACT
Friction stir welding (FSW) is a relatively new solid-state joining process. This joining technique is energy efficient,
environment friendly, and versatile. In particular, it can be used to join high-strength aerospace aluminumalloys and
other metallic alloys that are hard to weld by conventional fusion welding. FSW is considered to be the most
significant development in metal joining in a decade. The welded process is conducted on varying the welding
process parameters, tool rotation speed, welding speed (mm/min), download force (k/N) and tool pin profile. The
properties namely defects, microstructure, hardness, tensile and bend behavior on welded plates are studied and
compared with the base metal and the results show quality welds could be produced when the tool rotation has the
speed of 600-1200 rpm and tensile strength is reduced by about 10 % and the percentage elongation reduced almost
half compared to the base metal.
KEYWORDS
Friction stir welding ,Aluminium , tensile, hardness, microstructure
INTRODUCTION
Friction Stir Welding (FSW) is a simple, clean and
innovative joining technology for light metals
invented by The Welding Institute (TWI), England,
U.K. in 1991. Due to the high strength of FSW joints,
it allows considerable weight savings in lightweight
construction compared to conventional joining
technologies. The friction stir welding works on the
principle of a rotating pin emerging from a
cylindrical shoulder which is plunged between two
pieces of sheet and moved forward along the joint
line. The material is heated by friction between the
rotating shoulder and the work piece surface and
simultaneously stirred by the profiled pin leaving a
solid phase bond between the two pieces to be joined.
Special preparation of the weld seam and filler wires
is not required. The process of friction stir welding
has numerous advantages over the conventional
welding technologies. FSW process can take place in
the solid phase below the melting point of the metals
to be joined and is able to weld numerous materials
including, but not limited to aluminum, bronze,
copper, titanium, steel, magnesium, and plastic. It
also yields significantly less distortion than the fusion
welding processes, allowing for dramatic cost
reductions in many applications. Thus, all the
problems related to the solidification of a fused
material area voided. Materials classified as difficult
to fusion weld like the high strength aluminium
alloys used in the aerospace industry could be joined
with a minor loss in strength. The small-scale
industry can especially benefit from the low
investment costs of the mechanical equipment

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required for Friction Stir Welding. The ability to join
different aluminium and magnesium alloys offers a
great variety of new products.
REQUIRED MATERIALS
This work mainly concentrated on aerospace
application, it is advisable to consider properties of
the materials in such applicants. The most common
and important property is to considered for selection
is weight. A lighter aircraft requires less energy and,
hence, less fuel to operate. The materials selected are
Aluminium and Al2O3.
Aluminium(Metal Matrix): It is cheap and widely
used metal in production sector for both industrial
and domestic purposes, so developing a proper
welding process will only benefit production
deparrtments worldwide.Aluminium metal matrix
composites are potential materials for various
applications due to their good physical and
mechanical properties. The addition of
reinforcements into the metallic matrix improves the
stiffness, specific strength, wear, creep and fatigue
properties compared to the conventional engineering
materials.
AluminiumOxide(Al2O3)-(Reinforcement): It is one
of the most cost effective and widely used materialin
the family of engineering ceramics. The raw
materials from which from which this high
performance technical grade ceramic is made are
readily available and reasonably priced, resulting in
good value for the cost in fabricated alumina shapes.
With an excellent combination of properties and an
attractive price, it is no surprise that fine grain
technical grade alumina has a very wide range of
applications. Alumina oxide is a chemical compound
of aluminium and oxygen with the chemical formula
Al2O3.
Chemical properties of AA6061
Aluminium-96.85%, Magnesium-0.9%, Silicon-0.7%, Iron-0.6%, Copper-0.3%, Chromium-0.25%, Zinc-0.20%,
Titanium-0.10%, Manganese-0.50%, Others-0.50%
EXPERIMENTAL SETUP
TOOL PREPARATION
H13 Tool: H13 Tool steel is a versatile chromium-
molybdenum hot work steel that is widely used in hot
work and cold work tooling applications. The hot
strength of H 13 resists thermal fatigue cracking
which occurs as a result of cyclic heating and cooling
cycles in hot work tooling applications. Because of
its excellent combination of high toughness and
resistance to thermal fatigue cracking and also known
as heat checking. H13 is used for more work tooling
applications than any other steel. H-13 tool steel
which is characterized by high hardenability and
excellent toughness.
Aluminium tool- The weighted quantity of Al was
melted in an induction type tilting furnace in the
temperature range of 810 C. The alumina particles
were preheated in a separate furnace at about 810 C
for about 20 minutes before introducing theminto the
melting furnace. A stirrer (made of Mild steel) is used
to obtain an output of 600 rpm. During experimental
work, a four bladed 450 angled stirrer was chosen.
Steel tool-Tool steel is a type of carbon alloy steel
that is well-matched for tool manufacturing, such as
hand tools or machine dies. Its hardness,resistance to
abrasion and ability to retain shape at increased
temperatures are the key properties of this material.

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PROCEDURE
The friction stir welding a non-consumable rotating
tool with a specially designed pin and shoulder is
inserted into the abutting edges of sheets or plates to
be joined and traversed along the line of joint. The
tool serves two primary functions: (a) heating of
work piece and (b) movement of material to produce
the joint. The heating is accomplished by friction
between the tool and the work piece and plastic
deformation of work piece. The localized heating
softens the material around the pin and combination
of tool rotation and translation leads to movement of
material from the front of the pin to back of the pin.
By using the above tool we did the Friction Stir
Welding.
The specimen hence prepared are taken and few of
them are selected and cut into two halves and then
they are welded back together using friction stir
welding process.
Test specimen preparation and required specimen
1.TensileTest
Sl. No Welding Parameter Mechanical Properties
Tool Speed
(r.p.m.)
Feed
(mm/min)
UTS
(N/mm2)
Joint
Efficiency(%)
% of
Elongation
Breaking stress
1 Tool
Steel
1200 60 43.171 55 % 2.000002 22.826

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2 Tool
Steel
1100 40 48.184 61 % 2.828576 28.014
Conclusion
The conclusion drawn from the present work are
as follows
1. Different testes performed on friction stir
welded joint specimens of AL alloy with 6%
composition of Al2O3 with different tool
rotational speed and feed.
2. The Ultimate tensile strength of this welded
specimen at 1100rpm is high.
3. The breaking stress and % of elongation of
this weld specimen is high and Hardness is
less at 1100rpm.
4. Hence the overall joint efficiency is good at
1100rpm
40
42
44
46
48
50
1100 1200
N/mm2
rpm
ULTIMATE TENSILE
STRENGTH (N/mm2)
ULTIMATE
TENSILE
STRENGTH
(N/mm2)
0
10
20
30
1100 1200
N/mm2
rpm
BREAKING STRESS
(N/mm2)
BREAKING
STRESS
(N/mm2)
0
0.5
1
1.5
2
2.5
3
1100 1200
%elongation
rpm
% ELONGATION
Series 1

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