influ of tool pin and rotation speed on al alloy

8/7/2019 Influ of tool pin and rotation speed on Al alloy

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Materials Science and Engineering A 459 (2007) 718

Influences of pin profile and rotational speed of the tool on the formationof friction stir processing zone in AA2219 aluminium alloy

K. Elangovan, V. Balasubramanian

Department of Manufacturing Engineering, Annamalai University, Annamalai Nagar 608002, Tamil Nadu, India

Received 23 October 2006; received in revised form 13 December 2006; accepted 27 December 2006

Abstract

AA2219 aluminium alloy has gathered wide acceptance in the fabrication of light weight structures requiring a high strength-to-weight ratio.

Compared to the many fusion welding processes that are routinely used for joining structural aluminium alloys, friction stir welding (FSW) processis an emerging solid state joining process in which the material that is being welded does not melt and recast. The welding parameters and tool pin

profile play a major role in deciding the weld quality. In this investigation an attempt has been made to understand the influences of rotational speed

and pin profile of the tool on friction stir processed (FSP) zone formation in AA2219 aluminium alloy. Five different tool pin profiles (straight

cylindrical, tapered cylindrical, threaded cylindrical, triangular and square) have been used to fabricate the joints at three different tool rotational

speeds. The formation of FSP zone has been analysed macroscopically. Tensile properties of the joints have been evaluated and correlated with

the FSP zone formation. From this investigation it is found that the square tool pin profile produces mechanically sound and metallurgically defect

free welds compared to other tool pin profiles.

2007 Elsevier B.V. All rights reserved.

Keywords: AA2219 aluminium alloy; Friction stir welding; Rotational speed; Tool pin profile; FSP zone; Tensile properties

1. Introduction

AA2219 is most widely used material for the construction of

liquid cryogenic rocket fuel tanks. It has a unique combination

of properties such as good weldability, high strength-to-weight

ratio and superior cryogenic properties [1]. The preferred weld-

ing processes for AA2219 aluminium alloy are frequently gas

metal arc welding (GMAW) and gas tungsten arc welding

(GTAW) due to their comparatively easier applicability and bet-

ter economy [2]. However, plasma arc welding (PAW) with a

positive polarity electrode and high welding current allows alu-

miniumcomponents to be joinedeconomically with an excellent

weld quality [3]. In comparison with the TIG and MIG arcs,

the electron beam is characterized by higher power density and

thus permits the single pass welding of square butt joints with

thickness up to approximately 8 mm in the flat position [4].

Corresponding author. Tel.: +91 4144 239734;

fax: +91 4144 239734/4144 238275.

E-mail addresses: [email protected](K. Elangovan),

[email protected] (V. Balasubramanian).

ThoughAA2219 hasgot anedge over its6000and7000seriescounterparts in terms of weldability, it also suffers from poor as

weldedjoint strength.Thejoint strength is only about 40%when

compared to the base metal strength in T87 condition. This is

true both in autogenous welds as well as those welded with the

matching filler 2319, which contains slightly higher contents of

Ti and Zr. The loss of strength is due to the melting and quick

resolidification, which renders all the strengthening precipitates

to dissolve and the material is as good as a cast material with

solute segregation and large columnar grains [5].

Compared to many of the fusion welding processes that are

routinely used for joining AA2219 aluminum alloy, friction stir

welding (FSW) is an emerging solid state joining process in

which the material that is being welded does not melt and recast

[6]. Friction stir welding (FSW) was invented at The Welding

Institute (TWI), UK in 1991. Friction stir welding is a contin-

uous, hot shear, autogenous process involving non-consumable

rotating tool of harder material than the substrate material [7].

Fig. 1 explains the working principle of FSW process. Defect

free welds with good mechanical properties have been made in

a variety of aluminium alloys, even those previously thought

to be not weldable. When alloys are friction stir welded, phase

transformations that occur during cool down of the weld are of a

0921-5093/$ see front matter 2007 Elsevier B.V. All rights reserved.

doi:10.1016/j.msea.2006.12.124
mailto:[email protected]:[email protected]://dx.doi.org/10.1016/j.msea.2006.12.124http://dx.doi.org/10.1016/j.msea.2006.12.124mailto:[email protected]:[email protected]


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8 K. Elangovan, V. Balasubramanian / Materials Science and Engineering A 459 (2007) 718

Fig. 1. Schematic representation of FSW principle.

solid state type. Due to the absence of parent metal melting, the

new FSW process is observed to offer several advantages overfusion welding [8].

FSW joints usually consist of four different regions as shown

in Fig. 2. They are: (a) unaffected base metal; (b) heat affected

zone (HAZ); (c) thermo-mechanically affected zone (TMAZ)

and (d) friction stir processed (FSP) zone. The formation of

above regions is affected by the material flow behaviour under

the action of rotating non-consumable tool. However, the mate-

rial flow behaviour is predominantly influenced by the FSW

tool profiles, FSW tool dimensions and FSW process param-

eters [9,10]. The available literature focusing on the effect of

welding parameters and tool profiles on FSP zone formation in

AA2219 aluminum alloy is very scant. Hence, in this investiga-tionanattempt has beenmade to understand the effectof tool pin

profiles and rotational speed on FSP zone formation. This paper

presents the relation between the FSP zone formation and ten-

sile properties of friction stir welded AA2219 aluminium alloy

joints.

2. Experimental Work

The rolled plates of 6 mm thickness, AA2219 aluminium

alloy, were cut into the required size (300mm 150mm) by

power hacksaw cutting and grinding. Square butt joint con-

figuration, as shown in Fig. 3 was prepared to fabricate FSW

joints. The initial joint configuration was obtained by securing

the plates in position using mechanical clamps. The direction of

welding was normal to the rolling direction. Single pass weld-

Fig. 2. Different regions of FSW joint: (a) unaffected base metal; (b) heat

affected zone (HAZ); (c) thermo-mechanically affected zone (TMAZ); (d) fric-

tion stir processed (FSP) zone.

Fig. 3. Dimensions of square butt joint.

Fig. 4. FSW tool dimensions.

Table 1a

Chemical composition (wt%) of base metal

Cu 6.7

Mn 0.27

Si 0.01

Zn 0.04

Ti 0.05

Fe 0.13

Zr 0.12

Mg 0.01

Al Bal

ing procedure was used to fabricate the joints. Non-consumable

tools made of high carbon steel were used to fabricate the joints.

The tool dimensions are shown in Fig. 4. The chemical com-

position and mechanical properties of base metal are presented

in Table 1. An indigenously designed and developed machine

(15HP; 3000 rpm; 25 kN) was used to fabricate the joints. Five

different tool pin profiles, as shown in Fig. 5 were used to fab-

ricate the joints. Using each tool, 3 joints were fabricated at 3

different rotational speeds and in total 15 joints (5 3) were

fabricated in this investigation. Trial experiments were carried

out to find out the working limits of welding parameters. Three

differentwelding speeds (0.32 mm/s, 0.76 mm/s and1.25 mm/s)

and three different axial force levels (10 kN, 12 kN and 14 kN)

were used to fabricate the joints. Then the joints were visually

inspectedfor exteriorwelddefects andit was foundthat thejoints

Table 1b

Mechanical properties of AA2219-T87

Yield strength (MPa) 310

Ultimate tensile strength (MPa) 408

Elongation (%) 23

Vickers hardness (0.5 kg) 140


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K. Elangovan, V. Balasubramanian / Materials Science and Engineering A 459 (2007) 718 9

Fig. 5. FSW tool pin profiles.

Table 2

Welding parameters and tool dimensions

Process parameters Values

Rotational speed (rpm) 1500, 1600, 1700

Welding speed (mm/s) 0.76

Axial force (kN) 12

D/dratio of tool 3.0

Pin length (mm) 5.7

Tool shoulder diameter, D (mm) 18

Pin diameter, d(mm) 6

Tool inclined angle () 0

Shoulder deepness inserted into the surface

of base metal (mm)

0.2

Included angle of taper pin 7.5

Pitch (mm) and included angle () of

threaded pin

1 and 60

fabricated at the welding speed of 0.76 mm/s and axial force of

12 kN was free fromany externaldefects. Similar welding speed

was used by the other investigator [8] also to weld AA2219 alu-

minium alloy. The welding parameters and tool dimensions are

presented in Table 2.

The welded joints were sliced using power hacksaw and

then machined to the required dimensions to prepare ten-

sile specimens as shown in Fig. 6. American Society for

Testing of Materials (ASTM) guidelines were followed for

preparing the test specimens. Tensile test was carried out

in 100 kN, electro-mechanical controlled Universal TestingMachine. The specimen was loaded at the rate of 1.5 kN/min

as per ASTM specifications, so that tensile specimen under-

goes deformation. The specimen finally fails after necking

Fig. 6. Dimensions of tensile specimen.

and the load versus displacement was recorded. The 0.2%

offset yield strength, ultimate tensile strength and percentage

of elongation were evaluated. Vickers microhardness testingmachine (Make: Matzusawa, Japan and Model: MMT-X7) was

employed formeasuringthehardnessacrossthe joint with 0.5kg

load.

Macro- and microstructural analysis was carried out using

a light optical microscope (VERSAMET-3) incorporated with

an image analyzing software (ClemexVision). The specimens

for metallographic examination were sectioned to the required

sizes from the joint comprising FSP zone, TMAZ, HAZ and

base metal regions and polished using different grades of

emery papers. Final polishing was done using the diamond

compound (1m particle size) in the disc polishing machine.

Specimens were etched with Kellers reagent to reveal the

macro- and microstructures. The fractured surface of the ten-

sile tested specimens was analysed using digital scanner at

low magnification to study the general mode of fracture pat-

tern to establish the relationship between FSP zone and the

fracture.

3. Results

3.1. Macrostructure

In fusionwelding of aluminiumalloys, thedefects like poros-

ity, slag inclusion, solidification cracks, etc. deteriorates the

weld quality and joint properties. Usually, friction stir weldedjoints are free from these defects since there is no melting takes

place during welding and the metals are joined in the solid

state itself due to the heat generated by the friction and flow of

metal by the stirring action. However, FSW joints are prone to

other defects like pinhole, tunnel defect, piping defect, kissing

bond, cracks, etc. due to improper flow of metal and insuffi-

cient consolidation of metal in the FSP region. All the joints

fabricated in this investigation are analysed at low magnifica-

tion (10) using optical microscope to reveal the quality of FSP

regions.

The macrostructure of the joints and the observations (FSP

zone shape, FSP zone height (H), FSP zone width (W) at three


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Table 3

Effect of rotational speed on macrostructure of the joints fabricated by straight cylindrical pin profiled tool

Rotational

speed (rpm)

Macrostructure Size of FSP

zone (mm)

Shape of

FSP zone

Name of the

defect and

location

Quality of

weld metal

consolidation

Probable reasons

RS AS W H

1500 8.7 5.9 Inverted

trapezoidal

Tunnel in the

bottom of the

weld in the

retreating side

(RS)

Poor Insufficient heat

input and flow of

the plasticized

metal

6.1

4.1

1600 9.2 5.9 Tunnel in the

root of the weld

in the retreating

side

No vertical flow

of the metal6.3

3.9

1700 11.1 5.8 Pinholes in the

retreating side

and the root of

the weld

6.2

4.6

different locations, quality of the FSP zone, etc.) made from the

macrostructure are presented in Tables 37. All the three joints

fabricated using straight cylindrical pin profiled tool (Table 3)

and tapered cylindrical pin profiled tool (Table 4) are found

to be defective irrespective of rotational speeds used. In the

case of threaded cylindrical pin profiled tool (Table 5) and tri-

angular pin profiled tool (Table 7), the joints fabricated at a

rotational speed of 1500 rpm are found to be defective. On the

Table 4

Effect of rotational speed on macrostructure of the joints fabricated by tapered cylindrical pin profiled tool

Rotational

speed (rpm)


zone (mm)

Shape of FSP

zone

Name of the

defect and

location

Quality of

weld metal

consolidation

Probable

reasons

RS AS W H

1500 7.4 5.8 Inverted

trapezoidal

Tunnel in the

bottom of the

weld in the

retreating side


input and flow

of the

plasticized metal

5.1

3.1

1600 8.4 5.9 Pinhole in the

middle of the weld

in the retreating

side

No vertical flow

of the metal6.1

4.3

1700 11.3 5.9 Tunnel in the

bottom of the

weld in the

retreating side

6.7

5.1


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Table 5

Effect of rotational speed on macrostructure of the joints fabricated by threaded cylindrical pin profiled tool

Rotational

speed (rpm)


zone (mm)

Shape of FSP

zone

Name of the

defect and

location

Quality of

weld metal

consolidation

Probable reasons

RS AS W H

1500 8.1 5.9 Inverted

trapezoidal

No defect Good Screw thread generate

more heat and exerts

an extra downward

movement to the

plasticized metal

4.3

3.1

1600 10.3 5.8 No defect Good 5.2

3.9

1700 11.2 5.9 Pinhole in the

middle of the

weld

Poor Excess turbulence of

the plasticized metal

due to higher

rotational speed

8.3

7.1

other hand, the joints fabricated using square pin profiled tool is

found to be free from defects (Table 6). From the macrostruc-

ture analysis, it can be inferred that the formation of defect

free FSP zone is a function of tool profile and rotational speed

used.

3.2. Tensile properties

Transverse tensile properties of FSW joints such as yield

strength, tensile strength, percentage of elongation and joint

efficiency were evaluated. Three specimens were tested at each

Table 6

Effect of rotational speed on macrostructure of the joints fabricated by square pin profiled tool

Rotational

speed (rpm)


zone (mm)

Shape of FSP

zone

Name of the

defect and

location

Quality of

weld metal

consolidation

Probable reasons

RS AS W H

1500 10.1 5.8 Inverted

trapezoidal

No defect Good Sufficient working of the

plasticized metal due to

the pulsating action of the

pin profile

4.1

4.0

1600 10.0 5.9 5.7

3.3

1700 12.1 5.9 Excess working of the

plasticized metal with

wider FSP due to high

rotational speed

8.4

6.8


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Table 7

Effect of rotational speed on macrostructure of the joints fabricated by triangular pin profiled tool

Rotational

speed (rpm)


zone (mm)

Shape of FSP

zone

Name of the

defect and

location

Quality of

weld metal

consolidation

Probable reasons

RS AS W H

1500 7.4 5.9 Inverted

trapezoidal

Pinhole in the

retreating side


input and flow of

the plasticized

metal

4.8

3.3

1600 8.6 5.9 No defect Good Adequate heat

input and flow of

the plasticized

metal

5.8

4.3

1700 9.1 5.9 No defect Good

5.9

3.4

condition and average of the results of three specimens is pre-

sented in Fig. 7. From the figure, it can be inferred that the

tool profile and tool rotational speed are having influence on

tensile properties of the FSW joints. Of the five joints, the

joints fabricated by square tool profile exhibited superior tensile

properties compared to other joints, irrespective of tool rota-

tional speed. Similarly, the joints fabricated by threaded pin

profiled tool are also showing almost matching tensile prop-

erties to that of square tool profile. But the joints fabricated by

straight cylindrical tool profile exhibited inferior tensile proper-

Table 8

Effect of rotational speed on fracture surface of the joints fabricated by straight cylindrical pin profiled tool

Rotational speed (rpm) Fracture surface Location of

fracture

Fracture surface

appearance

Orientation of defects

1500 Between FSP

and HAZ of

retreating side

Coarse granular

appearance with

concave surface

Groove corresponding

to the tunnel in the

weld cross section

1600 Uneven surface with

mixed mode pattern

1700 Irregular surface with

dull grey fibrous

appearance

Groove corresponding

to the pinhole in the

weld cross section


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Fig. 7. Effect of rotational speed on tensile properties: (a) tensile strength; (b) yield strength; (c) percentage of elongation; (d) joint efficiency.

tiescompared to theircounterparts, irrespectiveof toolrotational

speed.

The joints fabricated at the rotational speed of 1500 rpm have

shown lower tensile strength and elongation compared to the

joints fabricated at a rotational speed of 1600 rpm and this trend

iscommonfor allthe tool profiles.Similarly, thejoints fabricated

at therotational speed of 1700 rpmhavealso shownlowertensile

strength and elongation compared to the joints fabricated at a

rotational speed of 1600rpm. The effect of rotational speed is

concerned, the joints fabricated at a rotational speed of 1600 rpm

areshowing superior tensile properties compared to other joints,

irrespective of tool profiles. The fractured surfaces of the tensile

test specimens were scanned using a digital scanner and the

fracture patterns of all the joints and observations made from

the fractured surface are presented in Tables 712. From the

fractured surface analysis, it can be inferred that the defect free

welds are showing uniform deformation across the weld before

failure (Table 11).


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Table 9

Effect of rotational speed on fracture surface of the joints fabricated by tapered cylindrical pin profiled tool

Rotational speed (rpm) Fracture surface Location of

fracture

Fracture surface

appearance

Orientation of

defects

1500 Between FSP

and HAZ of

retreating side

Irregular surface

with fibrous

appearance along

with striations at

the top

Groove

corresponding to

the tunnel in the

weld cross section

1600 Uneven surface

with fibrous dull

grey appearance

Insufficient

consolidation

corresponding to

the pinhole in the

weld cross section

1700 Flat surface with

coarse granular

appearance

Groove

corresponding to

the tunnel in the

weld cross section

4. Discussion

From the experimental results (macrostructure, tensile prop-

erties and fracture surface), it is found that the joint fabricated

using square pin profiled tool at a rotational speed of 1600rpm

exhibited superior tensile properties compared to other joints.

The reasons for the better performance of these joints are

explained below.

4.1. Effect of tool pin profile

The primary function of the non-consumable rotating tool

pin is to stir the plasticized metal and move the same behind

it to have good joint. Pin profile plays a crucial role in mate-

rial flow and in turn regulates the welding speed of the FSW

process [11,12]. The pin generally has cylindrical plain, frus-

tum tapered, threaded and flat surfaces. Pin profiles with flat

Table 10

Effect of rotational speed on fracture surface of the joints fabricated by threaded cylindrical pin profiled tool

Rotational

speed (rpm)

Fracture surface Location of

fracture

Fracture surface

appearance

Orientation of

defects

1500 Between FSP and

HAZ of retreating

side

Flat and smooth

surface with bright

granular appearance

No defect

1600 Irregular surface with

fibrous dull grey

appearance

No defect

1700 Uneven surface with

fibrous appearance

along with striations

at the top

Groove

corresponding to

the pinhole in the

weld cross section


9/12


Table 11

Effect of rotational speed on fracture surface of the joints fabricated by square pin profiled tool

Rotational

speed (rpm)


fracture

Fracture surface

appearance


1500 Between FSP

and HAZ of

retreating side

Coarse granular

appearance with striations

at top and bottom

No defect

1600 Concave surface with

granular appearance (like

cup and cone fracture)

1700 Granular appearance with

striations at the bottom

Table 12

Effect of rotational speed on fracture surface of the joints fabricated by triangular pin profiled tool

Rotational

speed (rpm)


fracture

Fracture surface

appearance


1500 Between FSP

and HAZ of

retreating side

Uneven surface with

coarse granular

appearance along with

striations at the bottom

Groove corresponding to

the pinhole in the weld

cross section

1600 Flat surface with bright

granular appearance

No defect

1700 Irregular surface with dull

grey fibrous appearance

along with striations at

the bottom

No defect

Fig. 8. Effect of pin profiles on FSP zone hardness.

faces (square and triangular) are associated with eccentricity.

This eccentricity allows incompressible material to pass aroundthe pin profile. Eccentricity of the rotating object is related to

dynamic orbit due to eccentricity [13]. This dynamic orbit is

the part of the FSW process. The relationship between the static

volume and dynamic volume decides the path for the flow of

plasticized material from the leading edge to the trailing edge of

the rotating tool. This ratio is equal to 1 for straight cylindrical,

1.09 for tapered cylindrical, 1.01 for threaded cylindrical, 1.56

for square and 2.3 for triangular pin profiles. In addition, the

triangular and square pin profiles produce a pulsating stirring

action in the flowing material due to flat faces. The square pin

profile produces 100pulses/s and triangular pin profile produces

75 pulses/s when the tool rotates at a speed of 1500 rpm. There


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Fig. 9. Effect of tool pin profiles on FSP zone microstructure: (a) straight cylindrical; (b) taper cylindrical; (c) threaded cylindrical; (d) square; (e) triangular.

is no such pulsating action in the case of cylindrical, tapered and

threaded pin profiles.

During tensile test, most of the specimens failed in the FSP

region but the exact location of failure is either at the retreating

side (RS) or at the advancing side (AS) and it is also evident

from the fracture surface analysis. Hence, microhardness mea-

surement and microstructural analysis have been carried out in

the FSP region of all the joints. Fig. 8 shows the microhardness

values and Fig. 9 displays themicrostructure of FSPregionof all

the joints fabricated at a rotational speed of 1600rpm for com-

parison purpose. Of the five joints, the highest hardness value

of 105 Hv has been recorded in the joint fabricated using square

pin profiled tool and the lowest hardness value of 82 Hv has

been recorded in the joint fabricated using straight cylindrical

pin profiled tool. Similarly, the FSP region of the joint fabri-

cated using square pin profile tool contains finer grains (Fig. 9d)

compared to other joints. The higher number of pulsating action

experienced in the stir zone of square pin profiled tool produces


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finer grained microstructure and in turn yields higher strength

and hardness.

4.2. Effect of tool rotational speed

Rotational speed appears to be the most significant process

variable since it also tends to influence the translational velocity.

Veryhighrotationalspeeds (>10,000 rpm)couldraisestrain rate,

andthereby influence therecrystallisationprocess;whichin turn

could influence the FSW process [14]. Higher tool rotational

speed resulted in a higher temperature and slower cooling rate

in the FSP zone after welding. A higher rotational speed causes

excessive release of stirred materials to the upper surface, which

resultantly left voids in theFSP zone. Lowerheat input condition

dueto lowerrotational speed resulted in lack of stirring.Thearea

of the FSP zone decreases with and decreasing the tool rotation

speed and affect the temperature distribution in the FSP zone

[15].

As the rotational speed increases, the strained region widens,

and the location of the maximum strain finally moves to theadvancing side from the original retreating side of the joint.

This implies that the fracture location of the joint is also affected

by the rotational speed [16]. The tensile properties of the joints

madewithdifferentwelding conditionsresulted in lowest tensile

strength and ductility at lowest spindle speed for a given tra-

verse (welding) speed. As the spindle speed increased, both the

strength and elongation improved, reaching a maximum before

falling again at high rotational speeds. It is clear that, in FSW,

as the rotational speed increases, the heat input also increases.

However, the calculated maximum temperatures are nearly the

same in all the rotational speeds. This phenomenon can be

explained by the following two reasons: first, the coefficient offriction decreases when a local melt occurs, and subsequently

decreases when a local input; secondly, the latent heat absorbs

some heat input.

Moataz and Hanadi [17] have opined that at very high rota-

tional speeds, second phase (strengthening) particles would

suffer more fragmentation and leads to segregation of par-

Fig. 10. Effect of rotational speed on FSP zone hardness (tool profile: square

pin).

ticles in other parts of the TMAZ. As the rotational speedis decreased, and the temperature within the nugget becomes

lower and the volume fraction of coarse second phase particles

increases. Hence, the tool rotation speed must be optimized to

getFSPregionwith fineparticlesuniformlydistributedthrough-

out the matrix. Of the three different tool rotational speeds,

the joints fabricated at a rotational speed of 1600 rpm exhib-

ited superior tensile properties, irrespective of tool pin profiles.

For comparison purpose, the microhardness and microstructure

of FSP regions produced by square pin profiled tool at different

rotational speedsarepresented in Figs. 10 and 11. Higher micro-

hardness and finer grain diameter have been obtained at the FSP

region of the joint fabricated at 1600 rpm using square pin pro-

filed tool. The combined effect of higher number of pulsating

stirring action during metal flow and an optimum tool rotational

speed may be the reason for superior tensile properties, higher

hardness and finer microstructure at the FSP region of the joint

fabricated at a rotational speed of 1600rpm using square pin

profiled tool.

Fig. 11. Effect of rotational speed on microstructure of FSP zone (tool profile: square pin).


12/12


5. Conclusions

In this investigation an attempt has been made to study the

effect of tool pin profile and tool rotational speed on the forma-

tion of friction stir processing zone in AA2219aluminium alloy.

From this investigation, the following important conclusions are

derived:

(i) Of the five tool pin profiles used in this investigation to

fabricatethe joints, squarepinprofiled tool produced defect

free FSP region, irrespective of rotational speeds.

(ii) Of the three tool rotational speedsused in this investigation

to fabricate the joints, the joints fabricated at a rotational

speed of 1600 rpm showed better tensile properties, irre-

spective of tool pin profiles.

(iii) Ofthe15 jointsfabricatedin this investigation, thejointfab-

ricated using square pin profiled tool at a rotational speed

of 1600 rpm showed superior tensile properties.

Acknowledgements

The authors are grateful to the Department of Manufacturing

Engineering, AnnamalaiUniversity, AnnamalaiNagar, Indiafor

extendingthefacilitiesof Metal Joining Laboratory andMaterial

Testing Laboratory to carryout this investigation. The authors

wish to place their sincere thanks to Aeronautical Research &

Development Board (ARDB), New Delhi for financial support

rendered through a R&D project No. DARO/08/1061356/M/I.

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influ of tool pin and rotation speed on al alloy

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