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Material presentation fsw - g03 (1)
1.
2. Friction stir welding is A process by which thermoplastic materials are
softened and welded together with heat produced by friction. Friction stir
welding is used particularly for joining aluminum alloys, the technology
provides significant advantage to the aluminum extrusion industry . the
maximum temperature usually lies between 425 and 500°C
4. The two pieces of metal to be welded together are placed into the two
holders. The rotating holder is connected to a flywheel. The rotating piece
is spun up to a high speed by a motor and then forced against the
stationary piece. The force remains applied for a while after rotation stops,
to allow the pieces to set.
5. Linear friction welding involves two holders, one of which vibrates and one
of which remains stationary. The two pieces of metal to be welded together
are placed into the two holders. The vibrating holder vibrates and is forced
against the stationary piece. The piece must be kept under constant
pressure for the joint to set.
6. Friction surfacing is a method of attaching a thin layer of one substance to
another. A rod made of the material to be coated is spun under pressure.
This creates a plasticized layer in the rod that is passed over the material to
be coated. The plasticized material is deposited on the base material and
fuses to it, creating the desired thin layer.
7. • As a solid state process it can be applied to all the major
Al-alloys and avoids welding process problems.
• No shielding gas or filler wire is required
• excellent mechanical properties
• No Fusion No Thermal contraction No distortion
• fewer welding passes are required (high thickness /pass)
8. • Exit hole left when tool is withdrawn
• Large down forces required (Clamping Force)
• Less flexible than manual and arc processes ( not in Site)
• difficulties with thickness variations and non-linear weld
• Often slower traverse rate than some fusion welding
techniques
12. • A downwards force: is necessary to maintain the position of the tool at
or below the material surface
• The traverse force : acts parallel to the tool motion and is positive in the
traverse direction (result of the resistance of the material T F )
• The lateral force : may act perpendicular to the tool traverse direction
and is defined here as positive towards the advancing side of the weld
• Torque is required to rotate the tool : the amount of which will depend
on the down force and friction coefficient
13.
14. • The tool is tipped with a probe, called a pin or nib, which typically rotates
within the range of 200 to 1400rotations per minute (rpm)
15. • he traverse rate of the tool along the joint line is between 20 to 120
millimeters per minute (mm/min)
16. • The tilt of the cylindrical tool can have major effects on the welding
process. A general range for tool tilt is between 2 and 4 degrees
• The tool shape effect the mechanical properties of the alloy
17.
18. Nugget Zone (SW – DXR) :
1. The grains within the stir zone
are roughly equiaxed and had
magnitude smaller than the
grains in the parent material
2. A unique feature of the stir
zone is several concentric
rings which is similar to
"onion-ring" structure.
3. the dislocation density is very
low but has a large toughness
19. TMAZ :
1. occurs on either side of the stir zone
2. Higher strength than the stir zone and lower deformation
3. Lower recrystallization than the stir zone
20. HAZ (heat affected Zone ):
1. No deformation
2. Had the poorest mechanical properties
3. Same of Base material Grains ,because the friction heat produced during
the FSW is not enough to result any change
23. Residual stresses arise from the accumulation of misfit between the weld
region and the remaining plate. There are a number of means by which
the misfit, and hence the residual stresses, can be manipulated:
1. thermal tensioning
2. mechanical tensioning
3. subsequent processing treatments.
24. Because of the high temprature and
the chemical composition of the alloy,
many types of corrosion appear :
1. (crack stress corrosion)
precipitation of a network of Cu
rich intermetallic at grain
boundaries
2. ( Localized corrosion ) this type
affect TMAZ at LT and HAZ at HT
3. galvanic corrosion in the nugget
4. potential Stress (Residual )
corrosion (HAZ)
25. 1. Surface Treatment ( Coating )
2. Post heating and pre heating processes
3. Heat Treatment
4. Laser Surface melting
