It is a type of solid state welding process,
in which explosive material are used to pressurise the specimen to brought
together and develop a joint between them by plastic deformation. The small
strength explosive are used which can generate appropriate pressure pulses to
produce plastic deformation in the metals. By this method dissimilar metal are
easy be joined. When the explosion takes place in the explosives a pressure is
developed which force one specimen towards another to generate the joint.
Explosion will generate the higher pressure force which cause a very quick
action in the specimen attached with the explosive material and further process
of joining also occurs very fast.
The explosive welding is not very old or
ancient metal joining process. The beginning of explosive welding happens about
1945. At that time it was not considered an efficient method of metal joining.
Then changes and developments has been done and the improvements has been
implemented. At present time explosive welding is an efficient method and
useful solid state welding process.
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| Explosion Welding Animation |
PREPARATION
OF EXPLOSIVE WELDING: -
In the preparation or setup of explosive welding
the two specimen will be kept at an angle as shown in the figure. This angle is
called collision angle. The specimen would be kept at some distance. This
separation is called standoff distance. One specimen should may be kept at
horizontal which must be rigidly fixed and other would be angled. The explosive
material is placed onto the specimen which is movable and kept at an angle to
the fixed workpiece.
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| Explosion Welding |
Process of Explosion Welding
- In the preparation of explosive welding all
the steps mentioned above should be followed. The standoff distance and
collision angle should be provided in the system.
- The explosive material is then ignited. The
burning of explosive material will proceed gradually form one end of the
specimen to another end.
- With the propagation of blast or explosion
the pressure will force the material to come close to each other and produce a
joint.
- Joining will take place simultaneous to the
explosion in the material.
Advantages of Explosion Welding
- This is a simple process and easy to
operate.
- Properties of material do not changes after
the process.
- Explosives with low intensity is used.
- Various material and large range of
thicknesses can be joined.
- Materials with different properties can be
welded which cannot be welded with conventional welding method because there is
no melting of material happens in the process.
- Sheets with large surface area can be
joined.
- It is a fast and time saving process and
the process can be implemented in mass production.
- It is an economical method of welding.
Disadvantages of Explosion Welding
- Safety equipment of good quality is
required due to noise and explosion.
- Specimen with complex geometries are
difficult to weld.
- The fixed specimen should have high
rigidity otherwise welding defect may occur.
- Appropriate intensity of explosion is
required for which the skill and knowledge is required to recognise the
suitable explosive material.
- Metal should have high strength, high
toughness so that it can wear the impact and pressure induced by the explosion.
- Operator should be experienced and skilled.
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