Explosion welding is a solid-state process that produces a high-velocity interaction of dissimilar metals by a controlled detonation.

1. Explosive Welding

2. Introduction
Principle of Explosion Welding
 Salient Features of Explosion Welding
 Explosives Materials
 Advantages & Disadvantages
 Applications
Contents

3.  Explosion welding is a solid-state
process that produces a high velocity
interaction of dissimilar metals by a
controlled detonation.
Introduction
 This eliminates the
problems of heat effects
& micro-structural
changes (as in fusion
welding).
 Oxides found on material surfaces must be removed
by effacement or dispersion
Fig. Explosive Welding

4. Principle of Explosion
 Cladder metal can be placed parallel or inclined
to the base plate.
 Explosive material is distributed over top of
cladder metal.
 Upon detonation, cladder plate collides with
base plate to form weld.
 Waves are generated so due to mechanical
bonding joining takes place.
 A single detonation cap can be used to ignite
the explosive.

5. Placement of Cladder metal-parallel
 Standoff distance
predetermined and unique to
material combination
• Achieved by placing shims
between plates
• Shims designed to be
consumed by explosion wave
and do not affect weld
 Usually ranges between 0.5-2
times the thickness of cladder
plate
 Cladder must reach critical
velocity before impact

6. Salient Features
 The high velocities are promoted by carefully
detonated explosives.
 The process can be done in vacuum to reduce
sound & blast.
 Typical impact pressure are millions of psi.
 Well suited to metals that are prone to brittle
joints when heat welded such as,
• Al on steel
• Ti on steel

7.  Typical explosive forms
• Plastic flexible sheer
• Cord
• Pressed shapes
• Cast shapes
• Powder/granular
 Detonation velocity is a function of
• Explosive type
• Composition of explosive
• Thickness of explosive layer

8. Assuring a Good weld
 Three types of Detonation wave welds:
• Shock wave develops if sonic velocity is greater
than 120% of material sonic velocity (type 1)
• Detached shock wave results when detonation
velocity is between 100% and 120% of material
sonic velocity (type 2)
• No shock wave is produced if detonation velocity
is less than material sonic velocity (type 3)

9. Explosive material
 High velocity (4572-7620 m/s)
• Trinitrotoluene (TNT)
• Cyclotrimethylenetrinitramine (RDX)
• Pentaerythritol Tetranitrate (PETN)
• Datasheet
• Primacord
 Mid-low velocity (1524-4572 m/s)
• Ammonium nitrate
• Ammonium perchlorate
• Amatol
• Nitroguonidine
• Dynamites
• Diluted PETN

10. Advantages of Explosion Welding
• Very large work pieces can be welded.
• (Al + Steel) materials can be welded.
• Can bond many dissimilar, normally unweldable
metals.
• Material melting temperatures and coefficients of
thermal expansion differences do not affect the final
product.
• Process is compact, portable, and easy to maintain.

11. • Welding can be achieved quickly over large areas.
• No need for surface penetration.
• Backer plate has no size limits.
• Inexpensive.
• The strength of the weld joint is equal to or greater
than the strength of the weaker of two metals joined.
• No heat-affected zone (HAZ).

12. Disadvantages of Explosion Welding
• Metals must have high enough impact resistance and
ductility
• The geometries welded must be simple-flat,
cylindrical, conical
• The cladding plate can’t be too large
• Noise & blast can require worker protection, vacuum
chambers, buried in sand/water.

13. Applications
• Cladding of base metals with thinner alloys e.g.
cladding of Ti with mild steel.
• Seam and lap welds.
• Reinforcing aerospace materials with dissimilar metal
ribs.
• Heat exchangers.
• Tubular transition joints.
• Used as a repair tool for repairing leaking tube-to-
tube sheet joints.
• Spot welding.
• Flat plates.
• Joining of pipes in socket joints.

14. Common industries that use Explosion Welding
• Petroleum Refining
• Chemical Processing
• Hydrometallurgy
• Aluminum Smelting
• Shipbuilding
• Electrochemical
• Oil & Gas
• Power Generation
• Cryogenic Processing
• Pulp & Paper
• Air conditioning &
Chillers
• Metal Production

15. Examples

16. Examples
3” Diameter AI/SS Ring Copper/Stainless 12” UHV Assembly