This document summarizes a study on friction stir processing of an aluminium and tungsten carbide composite. The researchers varied the tool shoulder diameter between 16-20 mm while keeping other parameters constant. They found that a shoulder diameter of 18 mm produced the finest grain size and maximum tensile strength and microhardness. Smaller and larger diameters produced less heat, resulting in coarser grains and poorer properties. Microstructure analysis showed more uniform reinforcement particle dispersion with an 18 mm diameter tool.

1. Journal for Research | Volume 03 | Issue 11 | January 2018
ISSN: 2395-7549
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Parameters of Friction Stir Processing Along
with Reinforcement of Composition of
Aluminium and Tungsten Carbide
Karamjeet Kaur Rakesh Kumar
PG Student Head of Department
Department of Mechanical Engineering Department of Mechanical Engineering
Northwest Instittute of Engineering and Technology
Dhudike, Moga, India
Northwest Instittute of Engineering and Technology
Dhudike, Moga, India
Amanpreet Singh
Head of Department
Department of Mechanical Engineering
Shaheed Bhagat Singh State Technical Campus
Ferozepur, India
Abstract
Friction stir processing (FSP) is a novel technique used for the enhancing the mechanical and metallurgical properties of the
material and also to make composites of the material. In this study, an attempt is made to synthesize the composites of AA6063
and tungsten carbide particles with 5 µm particle size were added reinforcement. The tool shoulder is varied from 16 mm to 20
mm. The other parameters such as tool rotational speed of 1400 rpm and transverse speed of 50 mm/min are kept constant. The
friction stir processing tool is made of high chromium high carbon steel with a pin length of 4 mm and pin diameter of 6 mm is
used. The 18 mm shoulder diameter produces much finer grain size with tungsten carbide reinforced particles rather than the
tools having shoulder 16 mm and 20 mm diameter. The maximum tensile strength and micro hardness achieved is 260 N/mm2
and 135 Hv respectively. In case of the tool having 16 mm diameter produces less amount of heat due to lesser contact with the
workpiece material and the tool having 20 mm diameter, over heat the workpiece material due to more contact area with the
workpiece and causes no proper plastization and flow of the material within the processed zone by friction stir processing and
produces courser grain size.
Keywords: Friction Stir Processing, Microstructure, Nugget, Aluminium, Plastisize, Microhardness, Tensile Strength,
Aa6063/Wc
_______________________________________________________________________________________________________
I. INTRODUCTION
Friction stir processing (FSP) is used to transform a heterogeneous microstructure to a more homogeneous, refined
microstructure. There are several possible methods available which can be applied to a variety of material shapes and sizes. In
many cases, the re-processed areas have superior strength and formability than the parent material, e.g. aluminum castings can be
processed to consolidate voids, or extrusions can be improved in highly stressed areas. In combination with super plastic
forming, FSP offers the potential to form complex-shaped parts at higher strain rates and in section thicknesses not possible
using conventional super plastic processing. Friction stir processing (FSP) is a novel micro structural modifications technique;
recently it has become an efficient tool for homogenizing and refining the grain structure of metal sheet. Friction stir processing
is believed to have a great potential in the field of super plasticity. Results have been reported that FSP greatly enhances super
plasticity in many Al alloy. Friction stir processing offers many advantages over conventional and other newer. One of the most
important and unique features of FSP is that FSP is a single step process, while other techniques require multiple steps which
make FSP easier and less time consuming. In addition, FSP uses a simple inexpensive tool, and a readily available machine such
as a milling machine can be used to conduct the process. Other advantages of FSP are that it is suitable for automation, and it is
also environmentally friendly since no gases or chemical are used. These features together make FSP easier, less expensive, and
so preferable over other processing techniques.
II. LITERATURE REVIEW
Friction stir processing has become the topic of research in the recent period. Many researchers investigated and formulated the
effect of friction stir processing which has produced composites layer on Aluminum, Steel, Nickel, Copper and Titanium alloy.
Research and development efforts over the last decade have resulted in improvements in friction stir processing. The researches
in the field of friction stir process a number of parameters are used by different researcher and calculate the effect of parameters on

2. Parameters of Friction Stir Processing Along with Reinforcement of Composition of Aluminium and Tungsten Carbide
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FSP. The present studies in which different parameters are used to calculate the effect of these parameters are tool pin profile,
transverse speed and reinforced particles. X. Weiping et al. (2011) observed that CNTs reinforced AA1100 and AA6101 matrix
composites by FSP are to create a good dispersion of CNTs in the matrix and to achieve a good combination with the matrix. The
interface of CNTs and pure aluminum matrix is smooth, no defects and is one kind of mechanical bonding interface. There are
large number of dislocations. CNTs can strengthen the matrix composites effectively and obviously improve the hardness of the
composites. K.G.Balamuruganet al. (2012) observed the effect of tool shoulder profile on the mechanical properties of friction
stir processed AZ31B magnesium alloy. From this it was found that the properties of the materials processed with concave
shoulder tool were governed by strain hardening effect. Gupta et al. (2013) studied that surface composite based on AL5083
matrix reinforced with nano-sized silicon carbide particles have been fabricated by Friction stir processing (FSP).The present
study reveals that the doping of AL5083 with hard SiC particles through FSP leads to significant increase in hardness of the
surface composite produced on FSPed sample layer. The hardness is maximum at center (155 HV) of processed zone at 60
mm/min and 500 rpm. The wear resistance of FSPed sample is inferior to that observed for 5083Al in spite of its higher
hardness. [21]D. Deepak et al. (2013) observed that the doping of 5083Al with hard SiC particles through FSP leads to
significant increase in hardness of the surface composite produced on FSPed sample layer. The wear resistance of FSPed sample
is inferior to that observed for 5083Al in spite of its higher hardness. It may be attributed to high coefficient of friction and
higher friction force observed during the wear testing of FSPed sample, owing to detachment of hard SiC particles from the
surface of FSPed sample during the course of wear. [40]N. Saini et al. (2014) concluded the effect of input process parameters of
friction stir processing to enhance the mechanical and tribiological performance of the cast hypereutectic Al-17%Si alloy. The
FSP of cast Al-17% Si has been performed with designed tool dimensions such as shank diameter 25 mm, shoulder diameter
18mm, pin diameter 8mm, pin length 3.5mm and the significant refinement of eutectic and coarse primary Si particles and there
was improved distribution of Si particles in the Al matrix takes place as a result of FSP in cast Al-17% Si alloy. [39]R.
Srinivasuet al. (2014) observed that friction stir processing of cast A356 Aluminium alloy is done to improve the surface
properties of the aluminium with B4C particles. The microstructure of the material is improved significantly and form hard
surface composite by reinforcing boron carbide particles in the aluminium matrix. [44] S.R.Babuet al. (2014) observed the role in
producing a defect free processed zone. The tool shoulder diameter of 18 mm produced the defects such as tunnels, voids and pin
holes in the processed region for different parameter variations in 6 mm thick plate. With increase in the tool shoulder diameter
beyond 18mm but less than 24 mm, a defect free processed zone was observed for variation in the process parameters in 6mm
thick plate. As the thickness of workpiece is reduced, the defects in the friction stir processed zone of 1.5 mm thick plate is
completely eliminated. A fine grain of average grain size less than 10μm was observed in the nugget region [38] R.Sathiskumaret
al. (2014) observed that area of the surface composite increased when tool rotational speed was increased and reduced when
processing speed was increased due to increase in frictional heat generation and the area of the surface composite reduced when
groove width was increased. The distribution of B4C particles in the surface composites was influenced by tool rotational speed
and processing speed and the micro hardness was found to be 175 Hv at 800 rpm and 132 Hv at 1200 rpm. [32] N.Yuvarajet al.
(2015) observed that the friction stir processing (FSP) is used to fabricate AA5083 aluminum alloy with reinforced layers of
boroncarbide (B4C). The Micro and nano sized B4C reinforced particles were used. The microstructure of specimens with nano
B4C particles exhibits fine grain size, higher hardness (124.8 Hv), ultimate strength (360 Mpa) and wear rate (0.00327 mg/m) as
compared to the base material hardness (82 Hv), ultimate strength (310 Mpa) and wear rate (0.0057 mg/m). The micro hardness
of the Al/B4C nano compositesis higher than B4C micro particles. A. Nagamalleswara Rao (2016) study the effect on the
mechanical and physical properties of welding joints. These geometries are used extensively in aerospace vehicles, in nautical
vessels, pressure vessels, and automobile industries and not widely used because of its poor weldebility. To overcome this
barrier, weldebility analysis of Cu 2200 copper alloys with high speed steel H13 tool has been investigated. An attempt has been
made to investigate and evaluate the influence of the rotational speed of the tools, the axial force and welding speed on tensile
strength of Cu 2200 copper alloys joint..M A Unnikrishnan and Dhas. J Edwin Raja (2017) there is a consistent demand for
superior materials in every industry. The most commonly used material in these fields is Aluminium. Though it possess all the
properties up to some extent constant demand is pushing for alternate materials. Dissimilar alloys have been a relatively new
approach towards these fields. Friction stir welding dissimilar alloys is a big leap in Automobile sector.
III. RESEARCH GAP
After a study of fair amount of research papers, it was noticed that a less amount of work has been done regarding the effect of
tool pin profile and tool shoulder diameter on the mechanical and metallurgical properties of AA6063/WC composite. A limited
literature is available regarding the fabrication of AA6063/WC composition using three variables of tool shoulder diameter and
tool pin profile.
IV. RESULT AND DISCUSSION
The results obtained from tensile test, Impact Test, Micro hardness test, Microstructure Test. The Table shows the processed
Parameters of the FSP and other useful result.

3. Parameters of Friction Stir Processing Along with Reinforcement of Composition of Aluminium and Tungsten Carbide
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Table - 1
Tensile Testing Results
Specimen no. Tool Shoulder Diameter (mm) Tool Pin used
Tensile strength
(MPa)
Yield strength
(MPa)
Percentage elongation
(%)
1 16 LHT 248 216 9.2
2 18 LHT 260 221 8.4
3 20 LHT 243 211 10
4 16 ST 239 207 12.9
5 18 ST 250 211 11
6 20 ST 238 200 15
7 16 CT 244 211 11.9
8 18 CT 255 217 10
9 20 CT 241 209 13.1
Visual Inspection
There are some defects are found after the processing of the material in the visual inspection. The voids are produced at 30
mm/min with cylindrical taper tool. The voids occurred in the processed region. These voids occur due to the insufficient heat
input at the interface of tool shoulder and material and non-relieving of internal stresses and also due to insufficient contact
between tool shoulder and the work material during processing. The onion rings occur due to insufficient contact between the
tool shoulder and the work material there is insufficient heat is produced for the plastic deformation in the material and that’s
why these defects occurs in the material.
From fig maximum value of tensile strength is achieved with LHT tool because of proper heat generation and material flow
Fig. 1:
In this study the yield strength and percentage elongation of the tool having 18 mm diameter has more strength rather than the
16mm and 20mm tool diameter due to the production of appropriate heat in the material and causes proper plastization of the
material.
Fig. 2:

4. Parameters of Friction Stir Processing Along with Reinforcement of Composition of Aluminium and Tungsten Carbide
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Table - 4.2
Results of Impact Test
Specimen No.
Tool Shoulder
Diameter (mm)
Tool Pin profile Energy Absorbed in (J)
1 16 LHT 12
2 18 LHT 9
3 20 LHT 6
4 16 ST 20
5 18 ST 16
6 20 ST 12
7 16 CT 14
8 18 CT 11
9 20 CT 8
V. CHARPY IMPACT TEST
Samples that are ductile absorb a lot of energy. Samples that are brittle absorb little energy. Depending on the filler alloy used,
the details of the welding procedure, and the testing temperature, steels can exhibit either ductile or brittle behavior. Needless to
say, brittle behavior is undesirable, and the CVN test tries to screen out a WPS that would lead to brittle behavior.
Fig. 3: Effect of Tool Pin, Tungsten Carbide and Transverse Speed on Impact Value
Fig shows that the tool having 22mm diameter has the high impact strength as compared to other tool shoulders. The impact
strength is closely related to refinement, homogeneous distribution of the precipitate particles in nugget zone and reduction of the
matrix grain size. The tool having 22mm shoulder diameter produces more heat in the nugget zone due to the more production of
heat there is production of less fine surfaces which causes increase in impact strength of the material. But in case of tool having
20mm diameter there is proper production of heat that causes refined surfaces which makes the material brittle in nature.
Similarly, in case of tool having 18mm shoulder diameter has low impact strength but more has more impact strength than the tool
having 20mm shoulder diameter.
Micro Hardness Test
The Vickers hardness profile of the processed specimens was measured at a distance 2.5mm from the top surface of the specimen
thickness on a cross-section perpendicular to the processed direction using Vickers hardness tester with 200 gf loads for 10
seconds. Micro hardness of 6063 is 83 hv.
Table - 3
Results of Hardness
Specimen no Tool Shoulder Diameter (mm) Tool used Average hardness value(HV)
1 16 LHT 130
2 18 LHT 135
3 20 LHT 125
4 16 ST 117
5 18 ST 125
6 20 ST 113
7 16 CT 121
8 18 CT 129
9 20 CT 118

5. Parameters of Friction Stir Processing Along with Reinforcement of Composition of Aluminium and Tungsten Carbide
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Fig. 4: It Is Concluded that the Average Micro Hardness Optimum Value Obtained with 18 Mm Tool Shoulder Dia. with Left Hand Threaded
Tool
Figure shows that the tool having 20mm shoulder diameter produced maximum micro hardness value than the tools having
18mm and 22mm shoulder diameter. This happened due to the fact that the tool having 18mm shoulder diameter has lesser contact
area caused insufficient heat and there is clustering of the precipitates in the fsp zone which reduces micro hardness values [40].
But in case of tools having 20 mm diameter produces sufficient amount of heat and uniform dispersion of reinforced particles in
the stir zone. With 22 mm shoulder diameter homogeneous dispersion is achieved but associated heat involved in the process is
high because of more surface area contact. High heat causes courser gain size which further reduces micro hardness values.
VI. MICROSTRUCTURE
Effect of Tool Shoulder Diameter
Fig. 5: Effect of Tool Shoulder Diameter on Microstructure
The tool having 18 mm shoulder diameter produces finer grains in the FSPed region as shown in figure 4.6. This happens due to
the fact that the tool having 20mm diameter produces sufficient amount of heat in the work piece which causes the better material
flow and results in homogeneous dispersion of reinforced particles in aluminium matrix. In case of the tool having 18mm diameter
has smaller area of contact and produces lesser amount of heat in the work piece and hence there is no proper flow of material in
the processed region and there is no uniform distribution of the particles in the processed region as shown in figure 4.7. The tool
having 22mm diameter leads to have more surface area of contact and produces larger amount of heat in work piece due to friction
subsequently wider TMAZ region and then resulted in the deterioration of tensile strength.

6. Parameters of Friction Stir Processing Along with Reinforcement of Composition of Aluminium and Tungsten Carbide
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Effect of Different Tool Pin Profile
Fig. 6: Microstructure at 50 Mm/Min with Different Tool Pin
Microstructure with left hand threaded tool shows uniformly dispersion of reinforced particles. This is because of flow pattern
that’s vertical and horizontal. In case of square tool pin, it has more surface area therefore WC particles in microstructure are not
uniformly dispersed and are distributed in wider area of specimen. But as compare to cylindrical taper tool flow pattern is only in
one direction and hence agglomeration formed. The reinforced particles are trapped in holes and agglomeration is formed. With
using left handed threaded tool flow of material is in both direction of horizontal and vertical result in uniform dispersion of
reinforced particles. In taper tool only flow in one direction which lower UTS, yield strength and hardness as compare to LHT.
In square tool pin more area under processed and hence wider dispersion of reinforced particles.
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