P. M. KUMAR et al.: EFFECT OF PIN PROFILES ON THE MECHANICAL PROPERTIES OF FRICTION-STIR-WELDED ...
3–9
EFFECT OF PIN PROFILES ON THE MECHANICAL PROPERTIES
OF FRICTION-STIR-WELDED AA5383 AND AA7075
VPLIV OBLIKE TRNA NA MEHANSKE LASTNOSTI
VRTILNO-TORNO VARJENEGA AA5383 IN AA7075
Pandy Madhan Kumar
1
, Veerabathiran Anbumalar
2*
1
Department of Mechanical Engineering, Sri Nandhanam College of Engineering and Technology, Tirupattur 635603, India
2
Department of Mechanical Engineering, Velammal College of Engineering and Technology, Rameswaram High Road, Madurai 625009, India
Prejem rokopisa – received: 2019-03-13; sprejem za objavo – accepted for publication: 2019-09-08
doi:10.17222/mit.2019.056
Friction-stir welding (FSW) is an unyielding-state welding process developed by The Welding Institute, United Kingdom. FSW
is mainly based on the tool geometry, process parameters and welding material. The tool geometry plays the principle role in
obtaining desirable microstructures of the welds, improving the strength and fatigue resistance of the joints. Currently,
friction-stir-welding tools are designed using the trial-and-error method. In this study, three different types of FSW tools are
considered for the fabrication of butt joints from AA5383 and AA7075. Various tool profiles such as the cylindrical taper
projection, cylindrical thread-pin projection and triangle-pin projection are considered in the present study. The pin profiles are
assessed based on the weld quality during tensile tests and hardness tests conducted on welded samples. With the analysis, it is
found that the triangular pin produces sound welds at an 800-min
–1
speed, 20-mm/min feed and 4-kN load.
Keywords: friction-stir welding, microstructure, tool-pin profile, tensile strength, hardness
Vrtilno-torno varjenje (FSW) je proces varjenja, ki so ga razvili na In{titutu za varjenje v Angliji. Potek in karakteristike FSW
dolo~ajo predvsem geometrija orodja, procesni parametri varjenja in material, ki ga varimo. Geometrija trna orodja ima
pomembno vlogo pri doseganju `elene mikrostrukture zvara oz. pri izbolj{anju trdnosti in odpornosti proti utrujanju varjenega
spoja. Zaenkrat oblikovanje orodij za FSW temelji na metodi preizkus/napaka. V {tudiji so avtorji ocenjevali vpliv treh vrst
trnov FSW orodja pri izdelavi zvarnih spojev med plo{~ami iz dveh Al zlitin: AA 5383 in AA7075. Uporabili so naslednje
profilne geometrije trna orodij: cilindri~no sto`~asto, cilindri~no z navojem in trikotno. Na osnovi nateznih preizkusov in
merjenja trdote so ugotovili, da vse tri geometrije omogo~ajo izdelavo odli~nih zvarnih spojev. Na osnovi izvedenih analiz so
ugotovili, da s trikotnim profilom trna orodja lahko izdelajo dobre zvare pri hitrosti vrtenja orodja 800 min
–1
, njegovem pomiku
20 mm/min in obremenitvi (sili) 4 kN.
Klju~ne besede: vrtilno-torno varjenje, mikrostruktura, profil trna orodja, natezna trdnost, trdota
1 INTRODUCTION
The friction-stir-welding technique is a non-consum-
able unyielding-phase welding, which permits an
extensive scope of parts and geometries to be welded. W.
Thomas and his social group at The Welding Institute,
United Kingdom, conjured it in 1991. Friction-stir weld-
ing is used in modern industries such as shipbuilding,
aerospace, automobile production and other modern
manufacturing industries. It is frequently used for
non-heat treatable or powder-metallurgy aluminium
alloys, to which fusion welding cannot be applied. Thus,
the weld mechanism and the relations between the
microstructure, mechanical properties and process
parameters have recently become fundamental studies. A
detailed observation of the material microstructure in the
joint section shows that there is an area located at the
core of the weld, called "the nugget", where the original
grain and sub-grain boundaries appear to be replaced
with fine, equally recrystallized grains characterized by a
nominal dimension of a few micrometers. Friction-stir
welding, a modern and an environment-friendly solid-
state joining process is used for joining a family of
relatively light materials, especially aluminium and its
alloys.
The effectiveness of such a joint is strongly de-
pendent on the geometry of the tool, process parameters
and welding material. The tool geometric parameters,
such as the height, the pin shape and the shoulder surface
of the head, have a large influence on both the metal
flow and the heat generation due to friction.
28
During
friction-stir welding, various stirrer geometries are used
for producing AA6063-T1 butt joints. For this reason,
we have to investigate the mechanical properties of a
joint and compare them with the microstructure of the
joint. It was reported that a rotational speed of
2000 min
–1
and a welding speed ranging from
50 mm/min to 200 mm/min produced a good weld;
mechanical properties such as the tensile strength and
hardness of the joint were also investigated.
20
The
right-screw- and left-screw-geometry stirrer designs
provide for a sound joint with no blemish in the weld
metal, exhibiting an increased joint strength, better than
that of an aluminium-based metal.
7
Researchers also
Materiali in tehnologije / Materials and technology 54 (2020) 1, 3–9 3
UDK 620.1:621.7:621.791 ISSN 1580-2949
Original scientific article/Izvirni znanstveni ~lanek MTAEC9, 54(1)3(2020)
*Corresponding author's e-mail:
dranbumalarv@gmail.com (Anbumalar Veerabathiran)

investigated the effects of the tool geometry on
dissimilar friction-stir welding of polyethylene-poly-
propylene.
18
Four different pin profiles, including
threaded cylindrical, squared, triangular and straight
cylindrical ones were considered. The interaction effects
of welding variables, including the rotational speed and
traverse speed were also studied. In order to control the
material flow, the tools used were equipped with a
stationary shoulder.
14
Tensile tests and durometer hard-
ness tests were carried out and a microstructure analysis
was conducted for all welded joints. It was observed that
the threaded-cylindrical-pin profile produced mechan-
ically strong welded joints.
15
Tool-pin profiles were also examined to determine
the influence of the shoulder geometry on friction-stir
welding of 1-mm copper-DHP plates. Tool welds were
formed using three different shoulder geometries
including flat, conical and scrolled ones at a varying
traverse speed and rotation of the friction-stir-welding
tool. The flat-shoulder tool proved to be insufficient for
the welds because several defects were found in all the
weld samples. On the other hand, the scrolled-shoulder
tool is more effective than the conical one for the pro-
duction of defect-free welds. However, both geometries
require the lowest rotational speed to evade internal
defects. At the same welding parameters, superior grain
refinement, higher hardness and better strength are
achieved in weld nuggets also by means of a scrolled
FSW tool.
12
Studies proved the influences of various
rotational speeds and friction-stir-welding tool geomet-
ries on the macrostructure, microstructure and joint
strength. Four tool-pin profiles (a conical-thread pin, a
cylindrical conical-thread pin, a stepped conical-thread
pin and a flared Triflute-pin tool) and two rotational
speeds, 600 min
–1
and 800 min
–1
, were used. The results
indicated that the friction-stir-welding tool geometry
considerably influences the material flow in the nugget
zone and, consequently, the weld mechanical proper -
ties.
26
The influence of the pin geometry on various pro-
perties of friction-stir-welded samples made with tools
with different pin profiles was proved. In the case of
four-flute cylindrical-pin profiles, friction-stir welding
could not be performed on an aluminium alloy.
5
It was
found in a research that tool geometries such as the
cylindrical geometry, cone geometry, left-screw geom-
etry and right-screw geometry affect the weld properties
at a welding speed of 50–200 mm/min and rotational
speed of 2000 min
–1
. The mechanical properties such as
the tensile strength and hardness of a joint were also
investigated and compared with the microstructure of the
joint. The results show that the shapes of the left- and
right-screw stirrer provided for sound joints with no
voids in the weld metal and with an increased joint
strength that was higher than that of the aluminium-
based metal.
19
The effects of the shoulder geometry of a tool used
for milling-machine friction-stir-welded joints of alumi-
nium alloy 1100 on the microstructural evolution and
mechanical properties were studied. Three designs of the
shoulder geometry were evaluated to induce different
distributions of thermal cycles in the welding regions.
Thermal cycles were measured using thermocouples and
a data acquisition system. The system results showed
that the featured shoulder tools produced an important
effect on the thermal cycles, generating a wide plasti-
cized region and the biggest grain size in the stir zone
when compared with the flat-shoulder tool.
32
Resear-
chers studied the production to forecast the ultimate
tensile strength and hardness of the weld zone with and
without tool profiles. The response-surface methodology
deals with the movement of the material flow in
friction-stir-welded aluminum alloy 6082.
9
The effects of important welding parameters and tool
properties that affect the static strength of the friction-stir
spot welds of polymer sheets were determined. Different
tool-pin profiles, pin lengths and pin angles were used to
produce the joints. Based on the experiments, the effects
of the pin profile, pin length, pin angle and tool ro-
tational speed on the friction-stir spot-welding formation
and weld strength were determined for a specific alloy.
6
Improved heat-generating models for straight- and
tapered-shoulder geometries with different tool-pin
profiles for friction-stir welding were developed. They
were developed by considering the welding process as a
combination of pure sliding and pure sticking conditions.
According to the results, the amount of heat generation is
directly proportional to the number of edges in pin
profiles so that the heat generated in the profiles
increases from a triangular pin profile to a hexagonal pin
profile.
33
Experimental relationships among the process
parameters such as the rotational speed, welding speed
and axial force help us envisage the maximum tensile
strength. In addition, statistical tools, such as the cylin-
drical-pin profile, are used for such investigations.
4
In a study on the geometry and size effects of sam-
ples on the tensile properties of FSW AA 2024 joints,
2.5 times the tool shoulder is proposed for the gauge
length.
9
Different tool designs and their effects are
investigated and it is concluded that the pin profile is
related to the mechanical properties and the maximum
tensile strength is achieved for the cylindrical-pin profile
with an 8-mm diameter.
34
Some studies also reported that samples made with a
polygonal pin profile are hard and brittle in comparison
with the cylindrical-pin-profile samples.
22
There are
studies on the effects of three different tool geometries
and two joint geometries on the quality of AA
5083-H111 T welds made with friction stir welding
(FSW). All the tools have concave shoulders with diffe-
rent pin geometries: a threaded taper pin, a quadrangular
pyramidal and progressive pin, a partly threaded cylin-
drical and partly pyramidal pin. T-lap and T-butt joint
P. M. KUMAR et al.: EFFECT OF PIN PROFILES ON THE MECHANICAL PROPERTIES OF FRICTION-STIR-WELDED ...
4 Materiali in tehnologije / Materials and technology 54 (2020) 1, 3–9

configurations are also studied. The results show that no
significant change in the hardness is observed with any
combination of tool and joint geometries. The tensile-
strength efficiency of the joints welded with the prog-
ressive-pin tool was found to achieve the optimum
level.
16
According to a study on the effects of tool design,
new friction-stir-welding design features such as hollow,
fluted and thermally insulated designs provide for a good
welding thermal efficiency when compared to the
conventional tool for aluminium welding. The effects of
the tool-shoulder contact found during a thermal analysis
of friction-stir welding are reported in
21
. The results
show that the tool shoulder has a remarkable effect on
the mechanical properties of AA6082. Observation
revealed that the heat generation is higher between the
trailing edge and retreating side-leading edge corner in
the counter-clockwise direction and lower between the
retreating side and the trailing edge in the clockwise
direction. The results show that the welds produced with
a ridge shoulder tool exhibit superior properties with a
significantly lower axial force.
24
A literature review shows that the tool geometry is
the most important parameter for achieving better weld-
ing with friction-stir welding. It also shows that the tool
geometry is selected based on the material to be welded.
In the present work, three different types of tool geom-
etry are considered for joining dissimilar aluminium
alloys AA7075 and AA5383.
2 MATERIALS AND METHODS
The welding materials used for modern investigations
include aluminium alloys 5383 and 7075 whose chem-
ical compositions are obtained using a vacuum spectro-
meter. Aluminium alloy AA5383, also called Alloy 5S,
is the major alloying element. Magnesium and silicon are
the chief alloying elements; treatable precipitation-
toughened aluminium alloy AA7075 contains zinc as the
major alloying element.
27
Specimens of aluminium
alloys AA7075 and AA5383 are used in the present
study. The major alloying elements, magnesium and
silicon, are found in precipitation-hardened aluminium
alloy 7075. It is one of the universally used aluminium
alloys, formerly called the 7-series alloy.
Zinc as the most important alloying element is found
in aluminium alloy AA5383. This alloy is strong and its
strength is comparable to many steels. It was formerly
called the 5-series alloy. The material properties of this
alloy include a good fatigue strength, standard machin-
ability and resistance to corrosion, which is better than
those of the other aluminium alloys. The two aluminium
alloys are used for the research. The chemical com-
positions of AA7075 and AA5383 are shown in Table 1.
They were analyzed with a vacuum spectrometer.
29
Table 1: Chemical compositions (%) of AA7075 and AA5383
Alloy AA7075 (%) AA5383 (%)
Mg 2.374 4.237
Mn 0.028 0.579
Cu 1.564 0.012
Cr 0.251 0.064
Si 0.023 0.057
Al 90.05 94.78
2.1 Tool material
Tool steel is one of the commonly used friction-
stir-welding tool materials, allowing a weld of up to 50
mm. Here, welding deals with aluminium, copper and
magnesium alloys.
1
Tool materials exhibit excellent
machinability and thermal-fatigue resistance. Tool steels
might cause damage and deformation during friction-stir
welding of aluminium alloys and other low-melting-
temperature materials. Tool steel can be used to weld
both similar and dissimilar materials as lap joints or butt
joints. During the welding using a butt-joint arrange-
ment, a harder, high-carbon, high-chromium tool has a
remarkably excellent wear resistance amongst different
tool steels. H13 is characterized by shock and abrasion
resistance combined with red hardness. A triangular
tool-pin profile is shown in Figure 1.
This tool-pin profile has a high toughness and 5-%
chromium content. High-chromium stainless steel has a
very high corrosion resistance. The softer material is on
the retreating side and the tool material is on the
advancing side and thus the tool is given a slight offset
from the butt interface towards the softer material.
25
Stainless steel, high-carbon high-chromium steel, high-
speed steel, H13 and C40 materials have been joined
with tool steels. This high-carbon, high-chromium-steel
tool material is used in the present investigation and its
chemical composition is given in Table 2. It is noted for
its high dimensional stability in addition to a good wear
resistance and excellent edge-holding capabilities.
Table 2: Chemical composition of HCHCr
Components C Mg Si Ni Mo Cr
w/% 97.67 0.97 0.19 0.25 0.80 0.12
This composition hardens the material so that it can
sustain the high temperature in the stir zone generated
during friction stirring. The density of the material is
7.7–8.03 g/m
3
, the melting point is 1426 °C and its
P. M. KUMAR et al.: EFFECT OF PIN PROFILES ON THE MECHANICAL PROPERTIES OF FRICTION-STIR-WELDED ...
Materiali in tehnologije / Materials and technology 54 (2020) 1, 3–9 5
Figure 1: High-carbon high-chromium triangular tool-pin profile

elastic modulus is 190–210 GPa. Dies, cutters, measur-
ing tools and finishing rolls for tier-mill sand punches
are commonly made of high-carbon high-chromium
steel.
10
Plates of 50 mm × 100 mm are machined and
used as the specimens. The tool material used is HCHCr,
containing C, Mg, Si, Ni, Cr and Mo. These tools show
high dimensional stability with added wear resistance
coupled with excellent edge-holding qualities and,
hence, they are selected for the present investigation.
17
The welded blank of AA7075 and AA5383 can be used
in the automotive sector as well as the aerospace industry
where a high strength-to-weight ratio is the most desir-
able property.
13
Aluminium alloys of the 7xxx and 5xxx series are not
easily weldable with the conventional techniques. The
electrical-resistance technique is also used to weld a few
aluminium alloys. However, these techniques require an
extensive surface preparation and prevention of an oxide
formation, which is quite difficult and, thus, this limits
their use to specific applications.
8
The raw materials in
the form of plates that are 50 mm wide, 100 mm long
and 6 mm thick are machined using a milling machine to
make them parallel. The clamping system of the
friction-stir-welding machine, leading to uniformity of
the gaps between the plates is of crucial importance. The
thickness of the welding plates range from 0.5 mm to 10
mm and the experiments are carried out on the friction-
stir-welding machine.
2.2 Experimental set-up
One of the most important aspects of FSW is the
exploitation of a readily available vertical milling
machine; friction-stir welding involves a large welding
axial force of about 2500 kN and a fixture with proper
clamps is designed to prevent the movement of speci-
mens. The friction-stir-welding machine has a capability
of welding plates with a thickness of 0.5–10 mm.
Aluminium-alloy welded joints require a vertical head
attachment, accommodating high spindle speeds that
vary between 200 min
–1
and 4000 min
–1
, powered by
22-kW AC motor and with axis-stroke length movements
of 600 mm, 200 mm and 300 mm along the x, y and z
axes, producing professional tool-pin profiles. Friction-
stir-welding process parameter called the traverse feed
rate of the worktable is controlled by the automatic feed
system of the milling machine. A FSW process requires
a data acquisition system with suitable equipment for
acquiring relevant parameters and monitoring the
process.
Large forces that develop when a FSW tool pin
plunges into a workpiece to be welded directly affect the
base plate and cause the plates to drift apart. Hence, a
rigid clamping fixture is essential to withstand the forces
and prevent the extrusion of the plasticized material from
the joint interface to the bottom of the joint. The
thermal-expanding and buckling behavior that the plates
encounter during normal FSW conditions can also be
restrained by the clamping. In the present work, fixture
components are fabricated from mild-steel plates.
The base plate is prepared using mild steel, having a
size of 200 mm × 160 mm × 10 mm and it is machined
precisely to hold the clamping plates and stopper plate
for the AA5383 and AA7075 workpieces with a thick-
ness of 6 mm.
The friction-stir-welding tool and welding parameters
play a very important role, determining the weld-joint
characteristic. The experiment involving the major
factors affecting friction-stir-welding parameters and
tool design such as the tool rotational speed, welding
speed and axial force are considered. Various parameters
together with their ranges are selected and presented in
Table 3.
The weld joints are prepared using the Computer
Numerical Control software to maintain the consistency.
The welds are made by joining both plates (100 × 50 × 6)
mm to make a weld joint with a width of 100 mm and a
length of 100 mm. Workpieces are clamped firmly on the
machine table, with the backward tool tilted at an angle
of 0° throughout the length of the weld. The friction-stir
weld is initiated by positioning the FSW tool in such a
position that the tip of the pin just touches the upper
surfaces of the workpieces.
Table 3: Optimum parameters for preparing a welded joint
S. No.
Axial load
(kN)
Tool rotational
speed (min
–1
)
Worktable feed
(mm/min)
1 4 800 20
2 5 1000 25
3 6 1200 30
2.3 Tension test
The weld is recognized and a two-inch mark is made
to allow the measurement of the elongation before the
test sample breaks under tension.
2
The tensile test is
performed according to the IS 1608:2005 specifications
on the welded samples in a universal testing machine
with a capacity of 100 kN. The tensile-test pieces are
prepared and tested for each weld joint to ensure
consistency and the data obtained for the welded
specimens is shown on Figure 3.
P. M. KUMAR et al.: EFFECT OF PIN PROFILES ON THE MECHANICAL PROPERTIES OF FRICTION-STIR-WELDED ...
6 Materiali in tehnologije / Materials and technology 54 (2020) 1, 3–9
Figure 2: Fabricated friction-stir-welding machine fixtures

2.4 Hardness test
Hardness tests are conducted for both base plates,
namely aluminum alloys AA5383 and AA7075 and also
at the stir zone. To determine the effect of the tem-
perature on friction-stir welding, the hardness of the
welded stir zone is studied. The hardness of the welded
specimen is estimated according to the Rockwell hard-
ness ASTM E8 standard.
3 RESULTS AND DISCUSSION
The welded butt joints are tested mechanically by
conducting an ultimate-tensile test and a hardness test
used for identifying the best parameters and excellent
friction-stir-welding tool-pin profile; welded joints are
analyzed with a scanning electron microscope (SEM). In
the present investigation, welding is done by maintaining
both the welding speed and axial load as well as by
varying the rotational speed and tool pin profiles
individually. The welding is carried out for the two
dissimilar aluminum alloys, namely AA7075 and
AA5383, as shown in Figure 4.
3.1 Tensile examination
In the present work, the operation process parameters
such as the worktable feed, axial load and tool rotational
speed are considered; in addition, the triangle, cylin-
drical thread and cylindrical taper pins are used and their
influence on the mechanical properties are investigated.
The experiments conducted show that for the triangle-pin
profile, the tensile strength obtained for an axial load of
4 kN is 592 MPa. The tensile strength is decreased by
33 % by increasing the axial load by 1 kN.
It can be concluded that the material has high
strength when the axial load is low. In the case of cylin-
drical threaded tool, a similar observation can also be
made as an increase in the axial load from 4 kN to 6 kN
results in a decrease in the tensile strength from 183.1
MPa to 91.7 MPa. A similar observation is made for the
cylindrical taper tool. The tensile-strength values ob-
served for the cylindrical thread pin are 162.6 MPa,
75.1 MPa and 93.2 MPa for the loads of 4 kN, 5 kN and
6 kN, respectively Figure 5. Some researchers also used
a square tool and reported a value of 211 MPa for a
700-min
–1
tensile strength when welding aluminum
alloys AA5383 and AA7075.
29
Similar tensile-strength
values were obtained and reported for friction-stir-
welded aluminum alloys.
3.2 Hardness
The hardness ordeal conducted on the welded sam-
ples are in table the hardness value of the weldments
done using triangle pin profile such as 4 kN is 72 from
investigation triangle tool profile is effective when
compared to the cylinder thread and cylindrical taper
tool pin profile.
P. M. KUMAR et al.: EFFECT OF PIN PROFILES ON THE MECHANICAL PROPERTIES OF FRICTION-STIR-WELDED ...
Materiali in tehnologije / Materials and technology 54 (2020) 1, 3–9 7
Figure 3: Tensile-test specimens
Figure 4: AA5383-AA7075 welded specimens
Figure 5: Tensile examination results
Figure 6: Hardness results

Thus it can be concluded that mechanical properties
of the welded samples the researchers using square tool
is reported as 70 HRB for 700 min
–1
Rockwell hardness
value of welded aluminum alloys 5383 and 7075
alloys.
29
Similar kind of hardness values is obtained and
researcher reported friction stir welded aluminium
alloys.
Table 4: Hardness results
S. No. Pin profile
Applied load
(N)
Rockwell hard-
ness (HRB)
1 Cylindrical thread 980.665 40
2 Cylindrical thread 980.665 36
3 Cylindrical thread 980.665 32
4 Cylindrical taper 980.665 38
5 Cylindrical taper 980.665 24
6 Cylindrical taper 980.665 21
7 Triangle 980.665 71
8 Triangle 980.665 65
3.3 Microstructure of AA7075 and AA5383
The surface of the welded area exhibits uniform
grains; it is smooth due to proper welding, maybe also
due to the presence of new stir grains, improving the
hardness of the welding zone. The region difficult to
identify in the microstructure shows evidence of the
stir-zone grain content in the main zone. The micro-
structure of the welded aluminum alloys shown in
Figure 7 shows a proper and uniform fusion of the
materials because of the high temperature in the heated
zone.
In the stir zone, we recognize a very increasing hard-
ness value of the welded samples. The welding prog-
ression is homogeneous and controllable. As seen in the
figure, due to the result of the welding progression,
bumpy surfaces developed, proving that small weld burrs
can be observed on dissimilar aluminium alloys 5383
and 7075. In the weld-stir zone, small microcracks can
be observed, which may be a result of the friction-stir-
welding tool-pin profile.
4 CONCLUSIONS
In this present investigation, FSW of AA5383 and
AA7075 dissimilar joints was successfully accomplished
using different parameters, namely the welding speed,
axial load, tool rotational speed and tool-pin profile. The
weld quality at various tool rotational speeds, axial loads
and welding-table feeds was studied, with a special
emphasis on the tool-pin profile. Based on the tool-pin
profiles and their influence on the mechanical properties,
it is found that the triangle-pin profile provides for better
mechanical properties than the cylindrical taper and
cylindrical thread-pin profiles. It is concluded that a tool
rotational speed of 800 min
–1
, together with a
20-mm/min transverse feed and 4-kN axial load, gives
excellent tensile strength and a hardness value of 592
MPa.
5 REFERENCES
1
J. Q. Su, T. W. Nelson, R. Mishra, M. Mahoney, Friction Stir
Processing of Aluminum Alloy,Acta Materialia, 51 (2003), 713–729
2
K. P. Mehta, V . J. Badheka, Influence of tool pin design on properties
of dissimilar copper to aluminum friction stir welding, Transactions
of Nonferrous Metals Society of China, 27 (2017), 36–54
3
H. J. Chauhan, A. Chouhan, S. L. Meena, Experimental investigation
and non destructive testing of friction stir welded aluminium alloy
AA 6082 using tool with and without shoulder geometry, Inter-
national Research Journal of Engineering and Technology, 3 (2016),
2656–2664
4
F. Lambiase, A. Paoletti, A. Diilio, Effect of tool geometry on
mechanical behavior of friction stir spot welds of polycarbonate
sheets, The International Journal of Advanced Manufacturing
Technology, 88 (2017), 3005–3016
5
J. S. Jesus, M. Gruppelaar, J. M. Costa, A. Loureiro, J. A. M.
Ferreira, Effect of geometrical parameters on friction stir welding of
AA 5083-H111 T-joints, Procedia Structural Integrity, (2016),
242–248
6
R. John, K. V . Jata, K. Sadananda, Residual stress effects on near
threshold fatigue crack growth in friction stir welded aerospace
alloys, International Journal of Fatigue 25, (2003), 939–948
7
M. R. Hajideh, M. Farahani, S. A. DavoudAlavi, N. M. Ramezani,
Investigation on the effects of tool geometry on the microstructure
and the mechanical properties of dissimilar friction stir welded
polyethylene and polypropylene sheets, Journal of Manufacturing
Processes, 26 (2017), 269–279
P. M. KUMAR et al.: EFFECT OF PIN PROFILES ON THE MECHANICAL PROPERTIES OF FRICTION-STIR-WELDED ...
8 Materiali in tehnologije / Materials and technology 54 (2020) 1, 3–9
Figure 7: Microstructure observations of the stir zone of AA5383 and AA7075

8
I. Shigematsu, Y . J. Kwon, K. Suzuki, T. Imai, N. Saito, Joining of
5083 and 6061 aluminum alloys by friction stir welding, Journal of
Material Science Letters, 22 (2003), 353–356
9
G. Buffa, J. Hua, R. Shivpuri, L. Fratini, Design of the friction stir
welding tool using the continuum based FEM model, Materials
Science and Engineering A, 419, (2006), 381–388
10
H. Li, J. Gao, Q. Li, A. Galloway, A. Toumpis, Effect of friction stir
welding tool design on welding thermal efficiency, Science and
Technology of Welding and Joining, (2018), 1–7
11
Z. Zhang, W. Li, F. Wang, J. Li, Sample geometry and size effects on
tensile properties of friction stir welded AA2024 joints, Materials
Letters, 162 (2016), 94–96
12
A. Dorbane, B. Mansoor, G. Ayoub, V . C. Shunmugasamy, A. Imad,
Mechanical, microstructural and fracture properties of
dissimilarwelds produced by friction stir welding of AZ31B and
Al6061, Materials Science and Engineering: A, 651 (2016), 720–733
13
P. Cavaliere, E. Cerri, L. Marzoli, J. Dos Santos, Friction stir welding
of ceramic particle reinforced aluminium based metal matrix
composites, Applied Composite Materials, 11 (2004), 247–258
14
J. Unfried-Silgado, A. Torres-Ardila, J. C. Carrasco-García, J.Rodrí-
guez-Fernández, Effects of shoulder geometry of tool on micro-
structure and mechanical properties of friction stir welded joints of
AA1100 aluminum alloy, DYNA, 84 (2016), 202–208
15
M. K. Bilici, A. I. Yükler, M. Kurtulmuº, Influence of Tool Pin
Geometry in Friction Stir Spot Welded Polymer Sheets, Journal of
Scientific and Engineering Research, 3 (2016), 15–22
16
M. A. Waheed, L. O. Jayesimi, S. O. Ismail, O. U Dairo, Modeling
of heat generations for different tool profiles in friction stir welding:
study of tool geometry and contact conditions, Journal of Applied
and Computational Mechanics, 3 (2017), 37–59
17
K. K. Mugada, K. Adepu, Role of Tool Shoulder End Features on
Friction Stir Weld Characteristics of 6082 Aluminum Alloy, Journal
of The Institution of Engineers Series C, (2018), 1–8
18
J. R. Kim, E. Y . Ahn, H. Das, Y . H. Jeong, S. T. Hong, M. Miles, K.
J. Lee, Effect of tool geometry and process parameters on mecha-
nical properties of friction stir spot welded dissimilar aluminum
alloys, International Journal of Precision Engineering and
Manufacturing, 18 (2017), 445–452
19
R. S. Mishra, Friction stir welding and processing, Materials Science
and Engineering, R: Reports, 50 (2005), 1–78
20
E. Sabari, M. Jahazi, A. Khodabandeh, H. Ghasemi-Nanesa, Influ-
ence of tool geometry and rotational speed on mechanical properties
and defect formation in friction stir lap welded 5456 aluminum alloy
sheets, Materials & Design, 54 (2014), 381–389
21
S. Sivachidambaram, G. Rajamurugan, D. Amirtharaj, Optimizing
the parameters for friction stir welding of dissimilar aluminium
alloys AA5383/AA7075, ARPN J. Eng. Appl. Sci., 10, (2015),
5434–5437
22
W. M. Thomas, E. D. Nicholas, J. C. Needham, M. G. Murth, Fric-
tion Stir Butt Welding, International Patent Application, (1995), No.
PCT/GB92/02203
23
A. Meilinger, I. Torok, The importance of friction stir welding tool,
Production Processes and Systems, 6 (2013), 25–34
24
M. T. S. M. Said, D. A. Hamid, A. Ismail, M. A. Rojan, M. J.
Zainuddin, The Effect of Pin Size on Friction Stir Welded AA5083
Plate Lap Joint, Automobiles and Mechanical Engineering, (2015),
85–92
25
I. Galvao, R. M. Leal, D. M. Rodrigues, A. Loureiro, Influence of
tool shoulder geometry on properties of friction stir welds in thin
copper sheets, Journal of Materials Processing Technology, 13
(2013), 129–135
26
K. Kimapong, J. Kaewwichit, W. Roybang, P. Poonnayom, S. Chan-
tasri, Friction Stir Welding Tool Geometries Affecting Tensile
Strength of AA6063-T1 Aluminum Alloy Butt Joint, International
Journal of Advanced Smart Convergence, 4 (2015), 145–153
27
A. Heidarzadeh, H. Khodaverdizadeh, A. Mahmoudi, E. Nazari,
Tensile behavior of friction stir welded AA 6061-T4 aluminum alloy
joints, Materials & Design, 37 (2012), 166–173
28
K. Chiteka, Friction stir welding/processing tool materials and
selection, (2011)
29
N. Babu, N. Karunakaran, V . Balasubramanian, A study to estimate
the tensile strength of friction stir welded AA 5059 aluminium alloy
joints, The International Journal of Advanced Manufacturing
Technology, 93 (2017), 1–9
30
M. Bahrami, M. K. B. Givi, K. Dehghani, N. Parvin, On the role of
pin geometry in microstructure and mechanical properties of
AA7075/SiC nano-composite fabricated by friction stir welding
technique, Materials & Design, 53 (2014), 519–527
31
M. Guerra, C. Schmidt, J. C. McClure, L. E. Murr, A. C. Nunes,
Flow patterns during friction stir welding, Materials Characteri-
zation, 49 (2003), 95–101
32
R. Rai, A. De, H. K. D. H. Bhadeshia, T. DebRoy, Review: friction
stir welding tools, Science and Technology of Welding and Joining,
16 (2011), 325–329
P. M. KUMAR et al.: EFFECT OF PIN PROFILES ON THE MECHANICAL PROPERTIES OF FRICTION-STIR-WELDED ...
Materiali in tehnologije / Materials and technology 54 (2020) 1, 3–9 9