Int. J. Mech. Eng. & Rob. Res. 2014 Ashwani Kumar et al.
, 2014
ISSN 2278 – 0149 www.ijmerr.com
Special Issue, Vol. 1, No. 1, January 2014
National Conference on “Recent Advances in Mechanical
Engineering” RAME – 2014
Research Paper © 2014 IJMERR. All Rights Reserved
HEAT INPUT & JOINT EFFICIENCY
OF THREE WELDING PROCESSES TIG, MIG
AND FSW USING AA6061
Ashwani Kumar1*, Shakti Singh Gautam1 and Alok Kumar1
Friction Stir Welding (FSW) is a process in which the welds are prepared with the help of a tool
having a profiled pin. In this welding process the material does not reach to its melting point and
the welds are made in the plastic stage condition by applying an axial force on the stirred work
material keep halt with the help of the fixtures. Here, a short of comparison is made between
conventional welding processes TIG and MIG to FSW on the basis of heat input and joint efficiency.
For doing this AA6061 is used in the study. It was found that, for less heat input best weld joint
with higher efficiency up to 80% can be obtained with the help of FSW process as comparison
to TIG & MIG welding processes
Keywords: FSW, TIG, MIG, AA6061
INTRODUCTION This is the solid state welding process in
This new technique of welding was invented which the material does not reach at its melting
in 1991 by Wayne Thomas of The Welding point which reduces so many problems like
Institute (TWI) of United Kingdom. For the segregation, severer residual stresses,
distortion and evaporation of volatile elements.
Friction Stir Welding (FSW) the jobs (metal
Figure 1 shows the main processes.
sheets/metal plates) to be joined are aligned
and clamped to each other and placed on a Originally, the FSW has been develop for
backing material. A non-consumable joining high strength aluminum alloys and
cylindrical tool having a profile probe or pin advanced aluminum alloys produced by power
rotates and plunged in to the joint line. The tool metallurgy.
also does a transverse motion along the Friction Stir Welding in comparison to the
joining line, this produces the rubbing action automated gas metal arc welding improves the
and heat is generatedwhich softens the job and dimensional accuracy of the assembly
the heated soft job material stirred by the probe and produces a 30% increase in joint strength
and plastic flow of material takes place. (Soundararanjan et al., 2006).
1
Mechanical Engineering Department, Quantum School of Technology, Roorkee.
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Int. J. Mech. Eng. & Rob. Res. 2013 Ashwani Kumar et al., 2014
Figure 1: FSW Process
and its alloys create a possibility to get the best
joint with higher strength within the economic
constraints. Here, a short of comparison is
made between conventional welding
processes TIG & MIG to FSW on the basis of
heat input and weld efficiency using AA6061.
Working Material: Aluminium alloys widely
used in aerospace, automobile industries,
railway vehicles, bridges and high speed
ships, because it has light weight and higher
FSW relies on localized forging of the weld strength to weight ratio, corrosion resistance
region to produce the joint. In FSW heat is and ductility. In all the discussed areas welding
caused by rubbing of the tool faces against is the most used manufacturing process with
the work piece, and by viscoplastic dissipation a great challenge for designers and
of mechanical energy at high strain rates technologists.
developed through interactions with the tool. Aluminium alloy AA6061 (Al-Mg-Si) is the
During welding, the material along the joint is most widely used medium strength aluminium
heated to a softened condition transferred alloy, and has gathered wide acceptance in
around the periphery of the tool and the fabrication of light weight structures
subsequently recoalesced along the back (Balasubramania et al., 2007).
surface of the pin to produce weld.
The Extruded form of aluminium alloy
Minimization of distortion and residual stress
AA6061 is used in the present investigation. It
is extremely important in welding of thick
is heat treated up to 3000C. It was in the sheet
section material, such as in the ship building
form having thickness 6 mm and width 50 mm.
and heavy manufacturing industries (Lienert et
Chemical compositions, physical properties
al., 2003). It is evident that, aluminum and its
and mechanical properties of the material are
alloys are the best suitable materials used in
given in Tables 1, 2 and 3 respectively.
various industries like aerospace, shipbuilding,
automotive, architectures etc, as these are the Table 1: Chemical Composition
lightweight materials and provide the better of Aluminium Alloy AA6061
strength. The main advantage of using Mg Si Fe Cu Cr Mn Zn Ti Al
aluminum and its alloys, in the industries is that,
0.63 0.42 0.42 0.12 0.19 0.05 0.08 0.02 Bal.
the high strength to weight ratios may be
obtained. As we know that welding of aluminum
Table 2: Physical Properties
and its alloys is not an easy task, but the of Aluminium Alloy AA6061
invention of FSW makes easy to weld
Density Melting Point Modulus of Poison
aluminum and its alloys. Hence the use of FSW (g/cm ) 3 0
( C) Elasticity(GPa) Ratio
instead of conventional fusion welding
2.7 600 70-80 0.33
processes (TIG and MIG) to weld aluminum
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Int. J. Mech. Eng. & Rob. Res. 2014 Ashwani Kumar et al., 2014
Table 3: Mechanical Properties Table 4: Process Parameters Used
of Aluminium Alloy AA6061 in TIG, MIG and FSW
Yield Ultimate Elongation Reduction Hard- Process MIG TIG FSW
Strength Strength (%) in cross ness
(MPa) (MPa) sectional (HRB)
Welding Pana auto Pana auto Vertical
area (%)
machine Panasonic Panasonic Milling
280 310 16 11 65
Machine
METHODS Tungsten - 3 -
electrode
Three welding methods TIG, MIG and FSW
diameter (mm)
is used in the study. The different welding
parameters are shown in the following Filler rod/wire 1.6 3.15 -
Table 4. diameter (mm)
Voltage (volts) 20 20 -
RESULTS AND DISCUSSION
Current (amps) 180 170 -
Heat Input: Heat input is a relative measure of
the energy transferred during welding. It is a Welding speed 100 120 60
useful tool in evaluating welding procedures (mm/min)
within a given process. The cooling rate, weld Heat input 1.62 1.275 0.79
size and material properties may all be (kJ/mm)
influenced by the heat input.
Shielding gas Argon Argon -
Some welding codes place specific
Gas flow rate 15 15 -
controls on the heat input. To ensure high (lit/min)
quality in welded construction, it is important
to understand and apply these principles Tool rotational - - 635
speed (rpm)
(Funderburk, 1999).
Axial force (kN) - - 7
In TIG and MIG welding the main welding
process parameters are voltage and current Tool shoulder - - 16
while in case of FSW there are three main diameter (mm)
process parameters and these are rotational Pin diameter - - 7
speed of tool, welding speed or feed of tool (mm)
and axial pressure applied through the tool on
Pin length
the working material. (mm) - - 4.7
In case of TIG and MIG welding process the Tool tilt angle - - 20
heat input is given by the following relation,
Pitch (mm) - - 1
V × I × η × 60
Heat Input, q = ... (1) Tool pin profile - - Threaded
s × 1000 (anti-
clockwise)
where V = Voltage in volts;
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Int. J. Mech. Eng. & Rob. Res. 2013 Ashwani Kumar et al., 2014
I = Current in Amperes; FSW processes the heat input also less in
η = Arc efficiency is assumed as 0.75 FSW by 51.2%.
for TIG and MIG welding processes; Here it is cited that in case of FSW the heat
s = Welding speed (mm/min) (AWS, 1996) input is less or decreased relative to arc welds
TIG and MIG. Because of lower heat input the
In case of FSW process the heat input is mechanical properties of the weld increases
given by the relation as follows, and distortion and residual stresses reduces.
Heat Input, This becomes an advantage of the FSW
process.
2π
q = × μ × p × ω × Rs × η ...(2) Situation may be easily understood with the
3s
help of Figure 2. In this figure, it can be clearly
where, μ = Co-efficient of friction; seen that heat input is less in case of FSW
p = Normal force in kN; than that of the other two conventional welding
processes TIG and MIG.
ω = Rotational speed in rev/s;
Figure 2: Heat Input in Welding
RS=Shoulder radius in m; Processes TIG, MIG and FSW
s = Welding speed in mm/s
(Heurtier et al., 2006)
Peel et al. (2003) determined that as the
weld speed increase, there was less overall
heat applied because the tool moves more
quickly, thereby reduces the amount of frictional
heat (Peel et al., 2003)
After calculation, we get heat input 1.275
kJ/mm in TIG welding process and 1.62 kJ/
mm in MIG welding process which means, the
energy consumption or heat input was 27.06%
more in case of MIG welding process then in
TIG.
As we know that higher heat input lower will
On the other hand in case of FSW, the heat be the cooling rate and lower heat input cooling
input was 0.79 kJ/mm (for 635 rpm and 60 mm/ rate will be higher. This thing affects the
min, 7 kN). Means on less heat input we can mechanical properties of the weld material. In
get fine weld joint in comparison of TIG and case of welding, aluminium alloys, it should be
MIG welding process. keep in mind that the heat input should not
If we consider TIG and FSW process, it is reach at the value where temperature becomes
seen that the heat input is less in case of FSW too high and the mechanical properties of the
by 38%. In the same way in case of MIG and welding material degraded too much to get the
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Int. J. Mech. Eng. & Rob. Res. 2014 Ashwani Kumar et al., 2014
weld with good strength. In case of FSW the help of FSW shown the higher joint efficiency.
heat input is such that the welding material The joint efficiency is 80% in FSW. This value
does not reach at its melting point, because is 19.4% higher as compared to TIG welded
of that, it is possible in FSW that the material joint efficiency and 35.5% higher as compared
can be weld with fine mechanical properties to MIG welded joint efficiency. These results
having nice orientation of grains. show that the joint fabricated with the help of
FSW possess having higher joint efficiency.
Table 5: UTS and Joint Efficiency
of Welded Joints These efficiencies can be shown graphically
Type of Ultimate Joint as follows:
Joint Tensile Strength Efficiency
(MPa) (%) CONCLUSION
In the present work TIG, MIG and FSW welding
TIG 200 64.5
processes were used to weld aluminium alloy
MIG 160 51.6 AA6061. As we know that the welding of
FSW 248 80 aluminium and aluminium alloys is not an easy
task and it requires a lot of considerations for
Joint Efficiency: The joint efficiency is the the proper joining of the BM. Following
ratio of ultimate tensile strength of welded joint conclusions may be drawn from the study:
to the ultimate tensile strength of BM. The UTS
1. The heat input in case of FSW is less than
of different welds is shown in the table given
that of TIG and MIG welding processes.
below:
Among these three welding processes, in
The joint efficiency of TIG welded joint is FSW heat input are 38% less as compared
64.5% and the joint efficiency of MIG welded to TIG welding and 51.2% less as
joint is 51.6%. The joints fabricated with the compared to MIG welding process.
Figure 3: Tensile Properties of BM 2. In welded joints obtained by three welding
and Different Welded Joints processes, the joint fabricated by FSW
process exhibited higher joint efficiency
than that of TIG and MIG welding processes.
3. FSW joint efficiency is 19.4% higher as
compared to TIG welded joints and 35.5%
higher as compared to MIG welded joints.
4. With the help of FSW as comparison to TIG
and MIG, nice welds having higher joint
efficiency with less heat input can be get.
ACKNOWLEDGMENT
This work is acknowledged by IPED, COT.
Every time there was a support and keen
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Int. J. Mech. Eng. & Rob. Res. 2013 Ashwani Kumar et al., 2014
observation of Dr. R. S. Jadoun, present. FSW (2006), “Mechanical and Thermal
related work is done in MIED lab of IITR. Modelling of Friction Stir Welding”,
Journal of Material Process Technology,
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