2. •It
is an arc welding process wherein
coalescence is produced by heating the job
with an electric arc struck between a
tungsten electrode and the job.
•A shielding gas is used to avoid
atmospheric contamination of the molten
weld pool.
•This welding process can be done with or
without using a filler material.

3. Line Diagram Of TIG

4. Hot Wire TIG
In hot wire welding, filler wire is resistance heated until
close to the melting point and added to the weld puddle
behind the tungsten.
 This prevents the wire from chilling the weld pool and
allows the filler metal to flow out across the weld
puddle resulting in a smooth, attractive weld bead.
 Since nearly all of the full energy of the welding arc is
available for penetration or to generate the weld pool
and fusion, a two to three times faster travel speed is
realized.
 More wire can be deposited and fill rates are increased
with the added benefit of weld quality as good as or in
some cases better than with cold wire GTAW


9. Wire Entry

11. The location of wire entry into the weld pool
is critical.
o For hot wire GTA welding, wire entry is
normally at the rear of the puddle with the
wire deposited in the depression behind the
arc at the rise of the weld pool.
o This permits faster travel speed than with
cold wire GTAW where wire entry is at the
leading edge of the puddle.
o Hot wire travel speeds of 8-9 IPM (203-228
mm/min) are typical compared to about 4
IPM (101 mm/min) for cold wire GTAW.
o

12. Significance of Shield Gas
•
•
•
Gas coverage Shielding with inert gas is
particularly important for hot wire GTAW
applications because the larger weld pool and
length of solidifying/cooling weld passes
demand greater gas coverage.
Effective design of gas cups is essential for
hot wire GTAW.
Lamellar gas coverage is critical. There must
be adequate screening in the torch and the
gas lens must seal snugly around the
tungsten.

13. What is Trailing shield?




The use of trailing shields to provide gas coverage to
the entire weld zone is highly recommended for hot
wire GTA welding, especially for cladding operations
and at the top of the groove.
This helps the solidifying and cooling of the weld and
is critical for higher currents and welding speeds to
minimize the formation of oxides and the potential for
porosity.
In addition, a protected weld pool will have a lower
surface tension and low viscosity that will wet and
tie-in better.
The extent of coverage required depends on the
material being welded and the temperature.

14. Effects Of Shielding Gas on Weld
Puddle

15. 





The shield gas type and composition has been found to
have a major effect on the shape of the weld bead.
Gas mixtures can be adjusted to suit particular
applications.
The bead shape produced with helium shielding is flat
with good wetting and is ideal for cladding and overlays.
Argon produces a more rounded profile and deeper
penetration which is suitable for groove welding, while the
addition of small amounts of hydrogen can be used to
increase penetration.
Argon/helium mixes are generally preferred for hot wire
welding in grooves, and have been used in cladding and
buttering.
Hydrogen mixtures should not be used in applications
where hydrogen-induced cracking could occur.

16. Advantages
It is an automated process with high
levels of productivity
 Able to make high quality welds on
nearly all weldable metals and alloys.
 No need to remove slag.
 No spatter.
 No need to change electrodes.
 Higher deposition rate


17. High welding speed.
 Welding is possible in all positions.


18. Disadvantages
Higher welding skills are required (for
manual welding).
 It is very expensive compared to other
arc welding processes.


19. Applications
This process is used in joint welding and
overlay welding(ex: Pipeline
Construction)
 Ship Building
 Off shore engineering power station
construction.
 It is also used to make root-run in
important element structures.


20. Thank You