Aluminum alloys: fabrication, characterization & applications Effects of Multipass Friction Stir Processing on Microstructure and Mechanical Properties of Al-Zn-Mg (7039) Alloy Prashant Soni*, B.P. Kashyap*, N. Prabhu*, A.G. Rao**, V.P. Deshmukh** *Indian Institute of Technology Bombay **Naval Materials Research Laboratory, Ambernath 2/17/2010
Multipass Friction Stir Processing
Jun 19, 2015
This research was a part of my Dual Degree Thesis and presented at The Minerals Metals and Materials Society Annual Meeting and Conference held at Seattle, WA in 2010.
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Aluminum alloys: fabrication, characterization & applications
Effects of Multipass Friction Stir Processing on
Microstructure and Mechanical Properties of
Al-Zn-Mg (7039) Alloy
Prashant Soni*, B.P. Kashyap*, N. Prabhu*, A.G. Rao**, V.P. Deshmukh**
*Indian Institute of Technology Bombay
**Naval Materials Research Laboratory, Ambernath
2/17/2010
Contents
� Introduction
� Objectives
� Experiment
� Results and Discussions
� Summary
2/17/2010
Friction Stir Processing
R.S. Mishra, Z.Y. Ma / Materials Science and Engineering R 50 (2005) 1–78
2/17/2010
FSP = f(ω, υ, φ, λ, ∆, Τ)
ω • Tool Rotation Speed (rpm)
v • Tool traversing speed (mm/min)
φ • Tool tilt angle (upto 50)
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φ
λ • Tool design and geometry
ƥ Tool insertion depth
Τ • Pre-heating – for steel and titanium alloys
Grain size in Nugget zone
� ω/υ- Tool rotation speed to tool traversing speed
ω/υF
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to tool traversing speed
� F- shoulder pressure
� µ- Coefficient of friction
Peak Temperature
µ
Grain Size
Contents
� Introduction
� Objectives
� Experiment
� Results and Discussions
� Summary
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Objective
Why?
FSP
Why? Aluminum alloy
Multipass
Aluminum 7039
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Contents
� Introduction
� Objectives
� Experiment
� Results and Discussions
� Summary
2/17/2010
ExperimentElement Zn Mg Cu Cr Mn Fe Si Ti Al
Wt% 3.95 2.78 0.09 0.18 0.22 0.17 0.09 0.01 Bal
Second Pass
Third Pass
Friction Stir Processing parameters (As carried
out at NMRL)
Tool specification Tool steel
First Pass
Second Pass
Pin Al 7039 sheets
Pin diameter 6mm
Pin length 4mm
Tool rotation speed (rpm) 330 & 1000
ToolTraversing speed (mm/min) 40
Quenching medium (if any) -
No. of passes done 3
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Shoulder
Contents
� Introduction
� Objectives
� Experiment
� Results and Discussions
� Summary
2/17/2010
SEM
a) b)SEM images of the Nugget Zone obtained after electropolishingwith 80% Methanol + 20% perchloric acid, a) Base Metal; b) After one pass FSP; c) After Two pass; d) After three passes at 330 rpm and 40mm/min
c) d)
BASE METAL FIRST PASS
SECOND PASS THIRD PASS
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EBSD of the Nugget Zone
One Pass Two Pass Three PassBase Metal
At 330 rpm & 40mm/min
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EBSD of the Nugget zone
90µm90µm90µm
First Pass Second Pass Third Pass
At 1000 rpm and 40 mm/min
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Average Grain Sizes (µm) in the Nugget Zone
10
20
30
40
50
60
70
80
Avera
ge G
rain
siz
e (
µm
)
Average Grain Size vs Number of passes
300 rpm and 40mm/min
1000 rpm and 40mm/min
Number of passes 330 rpm & 40 mm/min 1000 rpm & 40 mm/min
0 75.2 75.2
1 8.6 9.3
2 8.7 9.7
3 11.8 11.2
0
10
0 1 2 3 4Number of passes
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Tensile Tests
Number of
passes
Yield
Strength
( at 0.2%
strain)
MPa
Ultimate
Tensile
Strength
MPa
Percentage
Elongation
Performed at the room temperature
100
120
140
160
180
Mp
a)
Tensile Test
0 65 123 19.8
1 92 164 15
2 91 150 11.3
3 79 155 16.5
-20
0
20
40
60
80
-0.05 0 0.05 0.1 0.15 0.2 0.25
En
gin
eeri
ng S
tress
(M
pa
Engineering Strain
BASE METAL
FIRST PASS
SECOND PASS
THIRD PASS
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Hardness DataNo. of Passes Hardness Range (VHN)
Base Metal 46.7
First Pass 48-52
Second Pass 48-57
Third Pass 48-60
70
Hardness Hv Plot at different passes
0
10
20
30
40
50
60
70
-10 -5 0 5 10
Hv
Distance from the center of the Nugget zone
1 Pass2 Pass3 Pass
Trail of the pin - taken as center of the Nugget zone
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High Angle/low angle Boundaries
0.08
0.1
0.12
Nu
mb
er
fracti
on
Relative comparison of the high angle boundaries
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0
0.02
0.04
0.06
6.5 9.5 12.5 15.5 18.5 21.5 24.5 27.5 30.5 33.5 36.5 39.5 42.5 45.5 48.5 51.5 54.5 57.5 60.5 63.5
Nu
mb
er
fracti
on
Angle (degrees)
FP
SP
TP
Fraction of High Angle Boundaries
80
85
Perc
en
tage o
f H
igh
an
gle
bo
un
dari
es
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70
75
1 2 3
Perc
en
tage o
f H
igh
Number of passes
Grain Average Misorientation
0.6
0.7
Avera
ge G
AM
valu
es
Relative comparison of Average GAM values at different tool rotation speeds
330 rpm
1000 rpm
0.4
0.5
0 1 2 3
Avera
ge G
AM
valu
es
Number of passes
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Kernel Average Misorientation
0.9
1
1.1
1.2
Avera
ge K
AM
valu
es
Relative comparison of Average KAM values at different tool rotation speeds
0.4
0.5
0.6
0.7
0.8
0 1 2 3
Avera
ge K
AM
valu
es
Number of passes
330 rpm
1000 rpm
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Contents
� Introduction
� Objectives
� Experiment
� Results and Discussions
� Summary
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Summary
� Grain size dropped suddenly from 75µm to 8µm in the very first pass
� After the second pass the grain size remained more or less the same
� In the third pass, grain size increased from 8µm to 11µm
� GAM value first increased and then decreased indicating work hardening in the first two passes and then annealing in the third pass
� Increasing the number of passes gives enhanced strength as well as enhanced ductility
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Acknowledgement
� Naval Materials Research Laboratory Ambernath
� National Facility of Texture & OIM, IIT Bombay� National Facility of Texture & OIM, IIT Bombay
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Thank YouThank You
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