1. Solid State Welding
Processes
Presented By:
Raju Panchal(13BME061)

2. Introduction
 It is a welding process, in which two work pieces are joined under a pressure
providing an intimate contact between them and at a temp. essentially below
the melting point of the parent material.
 Bonding is a result of diffusion of the interface atoms.

3. Physical Principles

4. Solid State Welding Processes
• Diffusion welding
• Explosion welding
• Friction welding
• Friction- stir welding
• Forge welding
• Cold welding
• Roll welding
• Hot pressure welding
• Ultrasonic welding, etc.

5. Explosion Welding
 Explosion welding was developed relatively
recently, decades after world war-II.
 This process is most commonly utilized to clad
carbon steel with the corrosion-resistant material
e.g. stainless steel, nickel alloy, titanium,
zirconium, etc.
 SSW process in which rapid coalescence of two metallic surfaces is caused by
the energy of a detonated explosive.
 The process is quite dangerous and should be performed under some experts
in specially designed chambers.

6. Common Explosives used

7. Advantages and Disadvantages
 ADVANTAGES
 Dissimilar material joining is
possible through this process.
E.g., Al to steel, Cu to steel,
Tungsten to steel, etc.
 No filler metal used.
 No external heat applied.
 Bonding is metallurgical,
combined with mechanical
interlocking that results from a
rippled or wavy interface
between the metals.
 DISADVANTAGES
 Brittle materials( Low impact
toughness) can not be welded.
 Extensive knowledge of
explosives is needed before the
procedure may be attempted
safely.
 The geometries must be simple.
 APPLICATIONS
 Joining of pipes and tubes
 Attaching cooling fins
 Major app. In pressure vessels

8. Friction Welding
 SSW process in which
coalescence is achieved by
frictional heat combined
with pressure.
1) Rotating part, no contact
2) Parts brought into contact
to generate friction heat
3) Rotation stopped and axial
pressure applied
4) Weld created

9. Advantages and Disadvantages
 ADVANTAGES
 Process yields a narrow HAZ
 Can be used to join dissimilar
metals
 APPLICATIONS
 Shaft and Tubular parts
 DISADVANTAGES
 At least one of the parts must
be rotational.
 Flash must be removed (extra
operation)
 Upsetting reduces the part
lengths (which must be taken
into consideration in product
design)

10. Friction Stir Welding (FSW)
 SSW process in which a rotating tool is fed along a joint line between two
work-pieces, generating friction heat and mechanically stirring the metal to
form the weld seam
 Distinguished from FRW because heat is generated by a separate wear-
resistant tool rather than the parts
 Butt joints in large aluminium parts in aerospace, automotive, and
shipbuilding

11. Friction Stir Welding

12. Advantages and Disadvantages of
Friction Stir Welding
 Advantages
 Good mechanical properties of
weld joint
 Avoids toxic fumes, warping,
and shielding issues
 Little distortion or shrinkage
 Non-consumable tool
 Disadvantages
 Keyhole at the end of each
weld
 Heavy duty clamping of parts is
required
 Backing bar required.

13. Diffusion Welding (DFW)
SSW process uses heat and pressure, usually in a
controlled atmosphere, with sufficient time for diffusion
and coalescence to occur
• Temperatures  0.5 Tm
• The process is often conducted in vacuum in order to
keep the bonded surfaces clean from oxides and air
contaminations.
• Plastic deformation at surfaces is minimal

14. DFW Applications
• Joining of high-strength and refractory metals in aerospace and nuclear industries
• Can be used to join either similar and dissimilar metals
• For joining dissimilar metals, a filler layer of different metal is often sandwiched
between base metals to promote diffusion
• DISADVANTES
• Relatively high initial investment in equipment
• The mating surfaces must be precisely fitted to each other.
• The surface preparation is required prior to welding process.
• Time consuming process with low productivity