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.

1. 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

2. Contents
Introduction
Objectives
Experiment
Results and Discussions
Summary
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3. Friction Stir Processing
R.S. Mishra, Z.Y. Ma / Materials Science and Engineering R 50 (2005) 1–78
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4. 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
∆ • Tool insertion depth
Τ • Pre-heating – for steel and titanium alloys

5. Grain size in Nugget zone
ω/υ-Tool rotation speed
to tool traversing speed
ω/υ
F
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to tool traversing speed
F- shoulder pressure
- Coefficient of friction
Peak Temperature
Grain Size

6. Contents
Introduction
Objectives
Experiment
Results and Discussions
Summary
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7. Objective
Why?
FSP
Why? Aluminum
alloy
Multipass
Aluminum
7039
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8. Contents
Introduction
Objectives
Experiment
Results and Discussions
Summary
2/17/2010

9. Experiment
Element 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

10. Contents
Introduction
Objectives
Experiment
Results and Discussions
Summary
2/17/2010

11. SEM
a) b)
SEM images of the Nugget Zone
obtained after electropolishing
with 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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12. EBSD of the Nugget Zone
One Pass Two Pass Three PassBase Metal
At 330 rpm & 40mm/min
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13. EBSD of the Nugget zone
90µm90µm90µm
First Pass Second Pass Third Pass
At 1000 rpm and 40 mm/min
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14. Average Grain Sizes ( m) in the Nugget Zone
10
20
30
40
50
60
70
80
AverageGrainsize(m)
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 4
Number of passes
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15. 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
Mpa)
TensileTest
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
EngineeringStress(Mpa
Engineering Strain
BASE METAL
FIRST PASS
SECOND PASS
THIRD PASS
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16. Hardness Data
No. 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 Pass
2 Pass
3 Pass
Trail of the pin - taken as center of the
Nugget zone
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17. High Angle/low angle Boundaries
0.08
0.1
0.12
Numberfraction
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
Numberfraction
Angle (degrees)
FP
SP
TP

18. Fraction of High Angle Boundaries
80
85
PercentageofHighangleboundaries
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70
75
1 2 3
PercentageofHigh
Number of passes

19. Grain Average Misorientation
0.6
0.7
AverageGAMvalues
Relative comparison of Average GAM values at different tool
rotation speeds
330 rpm
1000 rpm
0.4
0.5
0 1 2 3
AverageGAMvalues
Number of passes
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20. Kernel Average Misorientation
0.9
1
1.1
1.2
AverageKAMvalues
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
AverageKAMvalues
Number of passes
330 rpm
1000 rpm
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21. Contents
Introduction
Objectives
Experiment
Results and Discussions
Summary
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22. Summary
Grain size dropped suddenly from 75 m to 8 m 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 8 m to 11 m
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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23. Acknowledgement
Naval Materials Research Laboratory Ambernath
National Facility of Texture & OIM, IIT BombayNational Facility of Texture & OIM, IIT Bombay
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24. Thank YouThank You
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