2. Introduction
FSW (Friction Stir Welding) is the process of welding two pieces using friction
It is usually done on materials which are hard to weld using conventional fusion
based weldings e.g. MIG
This process first developed by TWI in 1991 as a solid phase welding process
3. FSW: Merits and Demerits
Merits Demerits
Metallurgical Environmental Energy
Solid phase process No shielding gas required Improved material
use (e.g. joining
different thickness)
allows reduction in
wight
Slow process due to mechanical dependency for heating up
and stirring material (Can be improved using high rotating
speeds and featured (textured) shoulder
Low distortion of workpiece No surface cleaning required Only 2.5% of the
enerfy needed for a
laser weld
Residual stresses and weak spots near weld zone
Good dimensional stability and
repeatability
Eliminate grinding wastes Decreased fuel
consumption in
light weight
structures
Needs a back plate and strong foundation (can be solved using
dublbe shoulder welding front and back of the weld line
simultaneously)
No loss of alloying elements Eliminate solvents Required for degreasing
Consumable materials saving, such as
rugs, wire or any other gases
Excellent metallurgical properties in the
joint area
Fine microstructure
Absence of cracking
Replacing multiple parts joined by fastener
4. Overview
Due to interesting and very useful features of this type of welding, we are eager to
develop a new tool that kind of solves prescribed shortcoming of FSW
IRFSW (In-situ Rolling Friction Stir Welding) is a recent improvement on FSW in
which an FSW tool is accompanied by roller balls in order to improve surface
quality
Improving surface quality and at the same time, improving mechanical properties
such as strength, grain size and finally enhancing fatigue behavior is the goal of
this study
5. IRFSW over FSW
Better mechanical properties and fatigue life in welding line
Smaller grain size
Increase in hardness values
Less weld flash and smoother surface thus better resistance to corrosion
Decrease in friction coefficient values
This improvements makes increasing fatigue life a formidable action
6. Review of recent works
So many papers regarding papers related to FSW are published solely on FSW,
influential parameters and on different materials
As FSW is a well-known process, with a preconception of audiences familiarity with
the subject, a skip to the IRFSW would be useful
There are only two papers on IRFSW so far which is being presented in the next
slide
7. Review of recent works
Title Authors Year Conclusion
In situ rolling friction stir
welding for joining
AA2219
Yongxian Huang , Long
Wan , Shixiong Lv , Jian
Zhang , Guansheng Fu
2013 • Eliminate weld flashes
• Average tensile strength improvement nearly 13%
• More than 20% increase in microhardness compared with conventional
FSW
• Smallest grain size in Rolling Zone (RZ) which is affected by dynamic
recrystallization due to rolling pressure
Gradient micro-structured
surface layer on aluminum
alloy fabricated by in situ
rolling friction stir welding
Yongxian Huang , Long
Wan, Shixiong Lv, Huijie
Liu, Jicai Feng
2013 • Gradient change in microhardness
• Decrease in friction coefficient compared with those of BM
• Enhancement of wear resistance
• Much more and smaller second-phase particles compared with BM
8. In depth review of In situ rolling friction stir welding for joining AA2219
9.
10.
11. In depth review of Gradient micro-structured surface layer on aluminum alloy
fabricated by in situ rolling friction stir welding
12.
13. Differences between this and former works
Processing thick plate with deep shoulder and ball penetration
Adding reverse track for improved surface quality and even retreating and
advancing sides properties and defect removal
Separable ball cages for multi-sized balls
Investigation of this method on fatigue life (because of surface improvement,
14. IRFSW specification of this work
IRFSW and FSW is done on butt joint of two AL6061 pieces with a thickness of
5mm
A fixture is built to fully fix specimen on milling machine
Welding is done on two passes including welding, stopping and then reversing
weld line for even distribution of properties in advancing and retreating side
21. Tensile Test Data on Al 6061 using
Series Description Stress F max Disp.
Fmax.
Disp. Break
MPa N mm mm
Black IRFSWed specimen, shoulder penetration 1mm, ball penetration 0.5mm 173.33 16473.20 5.75 7.31
Blue FSWed specimen, Shoulder penetration 1mm no rolling 112.31 13408.14 2.67 -
22. Fatigue
Study of fatigue is an inevitable aspect of today’s engineering
According to presented papers and performed work an improvement on fatigue
life is expected because of:
1- more dynamic recrystallization thus smaller grain size
2- harder suface
3- better surface quality
4- improved stress strain behavior in terms of yield stress and toughness
5- enhancement of wear resistance
6- removing weld flashes
23. Suggestions for future works
Controlling ball penetration using an active system controlled by force, needed
torque and temperature instead of a passive system controlled by gaskets
Investigating on other mechanical or thermal works after IRFSWing
Combining this method with other suface treatment methods such as LPB
24. Summary
IRFSW is an improvement on FSW in terms of mechanical properties and surface
related issues such as flashes and corrosion
Cons of this process consist of a need for stronger foundation due to increased
normal force and torque. As a result, speed of this process compared with similar
FSW process with the same machinery should be slower
