Friction stir Processing (FSP) is a new innovative technology developed based on the principle of Friction Stir Welding (FSW) technique.
In FSP, the ceramic particulates are reinforced into the base metal by adding it into the groove and Friction Stir Processing (FSP) is performed.
In this study, the aluminum alloy 6061 is chosen as the base metal, alumina and graphite Nano powder as reinforcement.
The process parameters such traverse speed of 64 mm/min and the tool rotational speed of 1060 rpm and tilt angle of 2deg were selected, The Friction Powder Processing was carried out on vertical milling machine.
New parameters such as powder type and number of passes were involved and we also study the effect of heat treatment.
The influence of FSP was checked using some tests such as the microstructure analysis that was carried out using optical microscope (OM) and the mechanical characteristics were analyzed using tensile test and hardness test.
The micrograph results revealed that powder particulates were evenly distributed in the stir zone and reduction in grain size also observed; the reason for the grain size reduction was stirring action of the FPP tool’s pin.
The tensile strength results showed a significant improvement in strength by a percent of
50% compared to base metal but when T6 heat treatment is applied, the tensile strength decreased.
2. Aluminum and Its Alloys are characterized by:
Relatively low density
(2.7 g/cm3 as compared to 7.9
g/cm3 for steel)
High specific strength
(strength to weight ratio)
Low melting point
High electrical and thermal
conductivities
3. Heat treatable
Not heat treatable
Aluminum alloys.
Deformable
cast wrought
deformation
is not
possible
1xxx pure aluminum Not heat treatable
2xxx Copper Heat treatable
3xxx Manganese Not heat treatable
4xxx Silicon Not heat treatable
5xxx Magnesium Not heat treatable
6xxx Magnesium, silicon Heat treatable
7xxx Zinc Heat treatable
Designation of Wrought Aluminum Alloys
4. Chemical composition OF AL 6061 ALLOY
Silicon minimum
0.4%, maximum
0.8% by weight
Iron no minimum,
maximum 0.7%
Copper minimum
0.15%, maximum
0.4%
Manganese no
minimum,
maximum 0.15%
Magnesium
minimum 0.8%,
maximum 1.2%
Chromium
minimum 0.04%,
maximum 0.35%
Zinc no minimum,
maximum 0.25%
Titanium no minimum,
maximum 0.15%
Other elements no more than
0.05% each, 0.15% total Remainder Aluminum
(95.85–98.56%)
5. Friction welding
is a class of solid-state welding
processes that generates heat
through mechanical friction
between a moving workpiece
and a stationary component.
No melt occurs
6.
7. A specially designed non-consumable
cylindrical tool is rotated and plunged
into the selected area
Tool has a small diameter pin with a
concentric larger diameter shoulder
When tool descended to the
part, the rotating pin contacts
the surface, rapidly friction
produced between tool pin and
metal surface heats and softens
a small column of metal.
When the shoulder contacts the
metal surface, its rotation creates
additional frictional heat and
plasticizes a larger cylindrical
metal column around the
inserted pin.
Axial force
Retreating
side
Trailing
edge of tool
Leading
edge
10. • Very good mechanical properties as proven by fatigue, tensile and bend
tests
• No fume, No porosity
• No spatter
• Low shrinkage
• Energy efficient
Advantages
The processed zone cools, without solidification, as there is no liquid, forming a
defect-free recrystallized, fine grain microstructure
11. limitations
• Welding speeds are moderately slower than those of
some fusion welding
• Work pieces must be rigidly clamped
• Backing bar required
• Keyhole at the end of each weld.
16. process parameters are grouped in
to two categories:
machine
controlled
parameters
tool controlled
parameters
Spindle rotational
tool traverse
speed
axial force or
plunge force
tool pin profile
shoulder diameter
pin diameter
pin length
tool tilt angle.
Number of passes(1.2.3)
Heat treatment(T6)
Powder type
Graphite,AL2O3,mix,non)
17.
18. Reviews
Rotational
speed
Ahmed Khalid Hussain
concluded increase in
rotational speed has
resulted in increase on
tensile strength.
S. Rajakumar et.al studied the influence
of process parameters on friction stir
welding of Al 7075 – T6 alloy and
concluded that higher tool rotation
speed resulted in higher heat generation
which caused slower cooling rate and
leads to formation of coarse grains which
in turn produced lower hardness
researchers studied the effect of tool rotational
speed in mechanical properties and concluded
that increase in tool rotational speed
increases both strength and elongation to
maximum and drops down for further increase in
speed
19. TOOL
profile
Different materials were
welded by different
researchers using various
tool pin profiles and came
to conclusion that the
joints fabricated using
square pin profile
had given the good
mechanical properties
Yan-hua Zhao et.al Concluded
that taper with screw
thread pin has given
good weld without defects.
For this screw thread taper
pin the tensile strength of
the weld joint can reach
75% of the base material.
20. Tilt angle
K. Reshad Seighalani et.al carried out an Investigation
on the Effects of the Tool Material, Geometry, and Tilt
Angle on Friction Stir Welding of Pure Titanium and
concluded that at higher tilt say 30 angles the
plasticized material easily escape from
the bottom of the tool shoulder which
leads to the formation of some voids at
the surface.
By reducing the tool tilt
angle to 10, the weld
produced was good
without defects
the general range of tool tilt angle is 1° to 4°.
21. Macrostructural zones in FSP
Unaffected base metal zone(A)
Heat affected zone(B)
TMAZ(C)
nugget zone(D)
22. Unaffected base metal zone [A]:
• there is no change in neither property nor micro
structure.
• unaffected by the heat or deformation
Heat affected zone [B]: material is influenced by
heat (thermal cycle) and leads to micro structural
changes.
TMAZ [C]
• this region experiences both temperature and
deformation, which are not sufficient to induce the
recrystallization in the material.
nugget zone [D]:
• The portion where the actual stirring takes place which leads to grain refinement
• Severe plastic deformation during welding in the stirred zone results in a new equiaxed fine
grain structure.
23. Experimental work
The used machine
Process requirement:
• we need a vertical movement to start the process.
• traverse movement to make the welding area between the two plates
• rotational movement to mix the two plates to make the welding area.
Because of these requirements of SFSW process a vertical milling
Machine is used.
25. Process steps
2)Making the groove
1 –clamping the wp with the vice
3- Determine the rotational speed of the tool and feed speed
4-Put WP on the special fixture and clamped it using the bolts in the sides of the fixtures.
5- fill the groove with the used powder
6- Start the machine and elevate the work table until the shoulder of tool contact with the surface of wp.
7- Start the rotational speed and feed.
8- When the welding reach to the end of the part, go down with the table and stop the machine.
9- Removing the specimen from the fixture and finishing it
50. 0
50
100
150
200
250
first pass second pass third pass
Tensile strength for Non heat-treated specimen
No powder
Alumina
Graphite
Mixture
6061alloy
Linear (6061alloy)
51. 0
50
100
150
200
250
first pass second pass third pass
Tensile strength for Heat-treated specimen
No powder
Alumina
Graphite
Mixture
6060alloy
Linear (6060alloy)
53. Using alumina powder achieve highest tensile strength with third pass in addtion to
heat-treating.
Alumina powder achieves results that exceeds base metal in all passes, moreover
hear-treating achieves higher values.
Graphite powder with second or third pass achieves high value.
Graphite powder with heat-treating achieves good value with third pass but heat
treating not recommended for first or second pass
Using a mixture between alumina and graphite also achieve good values especially
second and third pass with heat-treating, but first pass not recommended.
The condition without powder also achieved good results in all cases, the highest
with the first pass.
59. Alumina powder in second pass with heat-treating achieves the highest values
Also alumina in the other passes achieve high values with or without hrat-treating
but highest with heat-treating.
Without powder, condition achieves good values in all passes almost the same
values.
Powder mixture condition achieves good values but first pass is better.
Graphite is recommended with third pass but the first pass not recommended in case
of heat-treating.
Heat-treating with graphite reduce hardness.
