International Journal of Engineering Trends and Technology (IJETT) – Volume 17 Number 5 – Nov 2014
An Investigation of Mechanical Properties of
Aluminium 6063-T6 after Friction Welding Process
Al Faizal .B#1, Amarnath T S*2 ,Roshan T Ninan#3
#
PG Scholar, Assistant Professors, Mechanical Department
Musaliar College Of Engineering and Technology, Pathanamthitta, Kerala, India
Abstract— A study of the friction welding process is carried out
for Al 6063-T6. 3D model of the rotary friction welding is made.
Thermo transient analysis and static structural analysis is
carried out and steps were made to modify a conventional lathe
to rotary friction welding set up to obtain friction welding with
four different (250, 500, 775, and 1200) rpm and to find out its
mechanical properties The simulation process are carried out
with ANSYS workbench.
Keywords— Rotary friction welding, ANSYS workbench comma.
I. INTRODUCTION
Rotary friction welding, in which one component is rotated
against the other, is the most commonly used among the
processes, and many carbon steel vehicle axles and subaxles
are assembled in this way. The process is also used to
fabricate suspension rods, steering columns, gear box forks
and drive shafts, as well as engine valves, in which the ability
to join dissimilar materials means that the valve stem and head
can be made of materials suited to their different duty cycles
in service. Traditionally, friction welding is carried out by
moving one component relative to the other along a common
interface, while applying a compressive force across the joint.
The friction heating generated at the interface softens both
components, and when they become plasticised the interface
material is extruded out of the edges of the joint so that clean
material from each component is left along the original
interface. The relative motion is then stopped, and a higher
final compressive force may be applied before the joint is
allowed to cool. The key to friction welding is that no molten
material is generated, the weld being formed in the solid state.
The principle of this process is the changing of mechanical
energy into heat energy. One component is gripped and
rotated about its axis while the other component to be welded
to it is gripped and does not rotate but can be moved axially to
make contact with the rotating component. At a point fusion
temperature is reached, then rotation is stopped and forging
pressure is applied. Then heat is generated due to friction and
is concentrated and localized at the interface, grain structure is
refined by hot work. Then welding is done, but there will not
occur the melting of parent metal.
Briefly the friction-welding process consists in bringing
into contact two elements to be welded while one of the two is
static and the other is rotated rapidly on its axis. As the soon
as the heat generated by attrition at the interface is sufficient
for solid state welding without melting, the rotation is stopped
and the elements are forced together under pressure producing
ISSN: 2231-5381
local forging which concludes the intimate joining and also
expels at the joint all surface contamination and some of the
upset material called flash.
II. OBJECTIVE
A detailed study of the friction welding process is to be
carried out, 3D model of the rotary friction welding is to be
made. Thermo transient analysis and static structural analysis
is to be carried out and FW joints are to be produced from
specimen with different rpm (250, 500, 775, and 1200) and
their tensile and hardness characteristics are assessed.
Numerical simulation of welding process is to be modelled
using solid works and is converted to ANSYS to gain the
temperature field and finding strong friction welded joints for
different rpm are to be obtained within the given parameters.
The same parameters are to be used to make an experimental
welded joint. The tensile strength is analysed using UTM and
hardness is measured using hardness testing machine.
III. LITERATURE REVIEW
Ranjitsinh D. Jadeja et al [1] 2012. Develop a finite
element simulation of friction stir welding of AA6063-T6
Aluminium alloy. Dr.K.P.Narayanan et al [2] 2013. Study on
aluminium alloys. Strong friction welded joints for different
surface interfaces were obtained and mechanical characteristic
studies of the same were carried out. Biswajit Parida et al [3]
2012. Study of Mechanical properties and study of microstructural properties of Al-Alloy. Wichai Pumchan [4] 2011.
The experimental application of a friction stir welding of the
butt joints between aluminium AA6063 and AA7075 by
changing the parameter. Ali. Moarrefzadeh [5] 2011.
Numerical simulation of welding process in SIMPELC
method and by ANSYS software for gaining the temperature
field of carbon steel, the effect of parameter variation on
temperature field and process optimization for different cases
of electrode done. Pasquale Cavaliere [6] 2013. The fatigue
life and crack behaviour of several aluminium alloys FSW
joints have been presented. V. Balasubramanian et al [7] 2012.
The FSW process parameters such as, the tool rotational speed,
the welding speed and the axial force play a major role in
deciding the weld quality. Vivekanandan. P et al [8] 2012.
The influence of friction stir welding on the microstructure
and hardness of aluminium 6035 and 8011. P.John Maclins [9]
studied the effect of corrosion and low impact damage on
aluminium alloy 6063- T6.
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International Journal of Engineering Trends and Technology (IJETT) – Volume 17 Number 5 – Nov 2014
IV. MODELLING
A. Model Creation
As the rotary welding process can be modelled with
solidworks 2014, an Axisymmetric 3D model of Al 6063-t6
rods of dimensions 20 mm radius and 120 mm length was
made with symmetry about the Y axis. The model was
meshed with 3830 nodes and elements 1956 and two
displacement degrees of freedom in the X and Y directions
respectively. The thermal effect of friction welding process
depends on the friction type and melting point of the work
piece. Numerical simulation of welding process by ANSYS
software for gaining the temperature field of Al 6063 alloy
and find out the weld strength and quality of the weld with
different rpm
of rotating specimen. At contact surface of two parts make an
axial movement by giving free movement along y- axis and
also arresting movement along x and y axis. A pressure of
10MPa is applied at the constrained end of the stationary
specimen (i.e. at position “E” marked on fig 2).
C. Transient Thermal Analysis
A temperature load of 600°C (position “A” marked on fig
3.7) was given at the contact nodes since heat generation takes
place during welding process which is equal to 600°C and the
ends of two rods are given a temperature of 22°C (position
“B” marked on fig 3.7) assuming to be the atmospheric
temperature.
Fig. 3 Boundary condition for thermal analysis for 1200,775,500, 250 rpm
Fig. 1 Meshing of model, model is designed using solidworks and import it
to the ansys workbench. Tetrahedral element was used for meshing.
B. Static Structural for 1200, 775, 500 and 250 RPM
V. EXPERIMENTAL STUDY
Experimental studies included production of friction
welded joints from Aluminium Alloy rods with 20mm
diameters and 120mm lengths and with different rpm. (250,
500, 775 and 1200 rpm). After that the same were subjected to
tensile test and hardness test characteristic studies.
A. Friction Welding Setup Used
The basic frame work of the friction welding setup is a
medium duty lathe. The tail stock of the same was replaced
with chuck with adequate hydraulic system as per the
requirement of the friction welding process The RFW set up is
suitable to hold work pieces whose diameter ranges from
0.75mm to 25 mm. Hydraulic system can provide a pressure
up to 25 MPa
B. Tension Test
Fig. 2 Boundary condition for static structural analysis for 1200, 775,500 and
250 rpm.
A 1200,775,500 and 250 rpm is being applied to the part
connected with the head stock (i.e. at position “A” marked on
fig 2). The model is constrained by arresting rotation of
stationary specimen and axial movement of rotating specimen.
This is done by arresting X direction motion at the end nodes
of stationary specimen and Y direction motion at the end node
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Fig 4 ASTM Standard tensile specimen (All dimensions are in mm)
All the welded joints were then subjected to tensile
characteristic studies. Fig 4. Represents the tensile specimen
prepared from these combinations as per ASTM standards
(B557M) [9]. The value obtained for Maximum load, breaking
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International Journal of Engineering Trends and Technology (IJETT) – Volume 17 Number 5 – Nov 2014
load and percentage elongations were then tabulated and
hardness is measured using Brinell hardness testing machine
VI. RESULTS AND DISCUSSION
A. Equivalent Stress
The Von Mises stress values at the initial stage seemed to
be maximum on areas away from the constrained end regions
with a value of 8.6654 MPa. Towards the end of the process
the Von Mises stress was found to be maximum on end of
rotating work piece with a value of 13.8 MPa. At the initial
stage as well as in the final stage the minimum value of Von
Mises stress was obtained at the heat affected zone of
specimen with a value of 5.22 MPa for weld at 775,500,250
rpm and 9.66 MPa for 1200 rpm At the welding interface (the
contact region) the value of von-Mises stress is less than the
stress obtained at other regions.
material flowing. Figure 6 shows the strain rate distributions
for friction welding of Al6063-T6 alloy with different
1200,775, 500 and 250 rpm.
Fig. 7 Directional deformation at welded joint
C. Directional Deformation
Directional deformation along y-axis is shown in fig 7 the
job is symmetric along y-axis. From the obtained result shows
maximum deformation is occurred at weld joint 250 rpm with
8.7mm this is due to the increases in contact pressure and time
consuming for reaching its weld temperature at contact
surface.
TABLE I
PERCENTAGE SHRINKAGE AFTER WELDING PROCESS BY USING
SOFTWARE
Fig. 5 Equivalent stress at welded joint
B. Elastic Strain
Test series
Original
Change in
%
description
length (mm)
length (mm)
shrinkage
240
2.19
0.9125
240
3.83
1.59
240
7.66
3.19
240
8.75
3.65
Welded with
1200 rpm
Welded with
775 rpm
Welded with
500 rpm
Welded with
250 rpm
Fig. 6 Elastic strain at welded joints
The strain rate is an important physical parameter during
welding process. Therefore, the analysis was carried out to
consider the strain rate distributions in the friction welding
process. The most deformation that occurred in the interface
was as a result of high transient temperature and subsequent
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D. Contact Pressure Distribution
Flash formation is mainly depend on contact pressure at
weld zone from fig 8 shows contact pressure distribution
at weld zone. With Increases in rotational velocity of job
results decrease in contact pressure. If more contact
pressure results more flush will be form that will reduce
the length of job. Fig 7 shows change in length of job
with different rpm. From the ansys result it is clear that
more flush will form at job with 250 rpm because of
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International Journal of Engineering Trends and Technology (IJETT) – Volume 17 Number 5 – Nov 2014
increases in contact pressure value of 28.42MPa as
compared with other job with rpm of 1200,775 and 500.
process. From the experimentally it is clear that the rpm of job
is affect the weld quality and time for completing the job.
Friction increases with speed because friction resistance
depends on interface shear stress. If interface shear stress
increases with speed, friction will increase with speed. Due to
this heat developed at mating surface suddenly increases and
joined
TABLE III
PERCENTAGE SHRINKAGE AFTER WELDING PROCESS BY
EXPERIMENT
Test series
Original
Change in
%
description
length(mm
length(mm)
shrinkage
)
240
3.5
1.46
240
4
1.67
240
7
2.92
240
10
4.17
Welded with
1200 rpm
Welded with
775 rpm
Welded with
Fig. 8 Contact pressure distribution at weld zone for 250 rpm welded joint
500 rpm
E. Total Heat Flux
Welded with
The maximum total heat flux of the specimen is found to
7.829 W/〖mm〗^2 at one second is shown in figure 9
250 rpm
When increases in rotational velocity of job, result reduce
the deformation because of decreases in contact pressure and
time consuming for reaching its weld temperature at contact
surface. Table III shows percentage shrinkage after welding
process by experiment.
BHN VS LEN GTH
79
78
80
75
bhn
73
73
73
73
70
Fig. 9 Total heat flux for welded joints.
F. Experimental Results
TABLE II
TIME TAKEN FOR COMPLETING DIFFERENT WELDING
Speed of rotating
Time taken for completing the
chuck in rpm
welding operation in minutes
250
7.4
500
6.2
775
5.1
1200
2.58
It was found that increases the speed of rotating
component results reduce the time for finishing the welding
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60
67
66
65
67
66
65
63
63
-30
-20
-10
0
10
20
30
1200 rpm
73
73
67
79
67
73
73
775 rpm
73
73
66
79
66
73
73
500 rpm
73
73
65
78
65
73
73
250 rpm
73
73
63
75
63
distance from weld zone in mm
73
73
Fig 10 BHN distribution along welded specimen with 1200, 775,500 and 250
rpm.
Hardness distribution along the weld was investigated by
finding out Brinell hardness number (BHN) on both sides at
equal distances from the welded joint formed at 1200,775, 500,
and 250 rpm.
The increase in hardness at the plasticized zone is
attributed to the finer grain size of plasticized zone and strain
hardening effect due to upsetting. Thermal softening led to
reduction of hardness near the weld zone. Hence the weld
zone becomes almost softened. Then hardness increases and
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International Journal of Engineering Trends and Technology (IJETT) – Volume 17 Number 5 – Nov 2014
again decreases to reach a constant value. Hardness
distribution along the weld specimen is obtained as shown in
figures 10.
TABLE IV
TENSILE TEST RESULT FOR ALUMINIUM ALLOY 6063 WELDED
JOINT
Test
Test series
Maximum
Breaking
%
series
description
load (KN)
load
elongation
26.5
24.8
14
26.2
24.5
13.4
25.8
23.8
12
25.6
23.1
11.88
6.8
6
2.66
1
Parent material
[3].
[4].
[5].
[6].
2
3
4
5
Welded material
with 1200 rpm
Welded material
with 775 rpm
Welded material
with 500 rpm
Welded material
with 250 rpm
VII. CONCLUSIONS
The results of the tensile test shows that the weld zone is
stronger than the base metals since the rupture occurred
outside of the welding area. The quality of rotary friction
welding is depend on rotating velocity of members. In this
study it is clear that at high rpm material binds together due to
high material penetration and hence length of the workpiece is
reduced after welding. The weld zone was divided into three
regions based on the microstructure (center of weld and two
HAZ). The center of weld had fine grains due to dynamic
recrystallization with higher tensile strength and hardness. The
maximum hardness of 79 BHN is achieved at a weld speed of
1200 rpm that resulted in a high tensile strength compare with
other welded joints (775,500 and 250 rpm).
The study reveals that for Al 6063-T6 after friction welding
at 1200, 775 and 500 rpm the mechanical properties are
remains almost same as that of parent material. But at 250 rpm
the mechanical properties are reduced. This shows that the
speed of rotating member affect the quality of weld.
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