FIELD OF THE INVENTION
This invention relates to a novel flux and a method of TIG (Tungsten Inert
Gas)welding of pure titanium and its alloy (Ti6A14V) for increased penetration
using the flux.
BACKGROUND OF THE INVENTION
All welding processes rely on either gas shielding or slag shielding (produced
from a welding flux) or a combination thereof. Thus the SMAW (shielded metal
arc welding) process uses fluxes as a coating. In SAW (submerged arc welding) the
welding arc is buried under a blanket of flux which on melting protects the weld metal
and is finally discarded as slag.
TIG welding or tungsten inert gas welding uses a non-consumable Tungsten
electrode to establish the welding arc and welding can be performed with or
without filler material. An inert gas like argon or helium is used to shield the
weld metal from atmospheric contamination. When the welding is carried out
without addition of filler it is known as autogenous TIG welding.DCEN current
polarity is the preferred current for welding of titanium and its alloy (Ti6A14V).
Weld penetration is the distance that the fusion line extends below the surface
of the material being welded. Welding current is of primary importance to
penetration. Weld penetration is directly related to welding current. An increase
or decrease in the current will increase or decrease the weld penetration
respectively.
In conventional TIG welding, there is no scope or role for flux. The primary task
of protection of weld metal from atmospheric contamination is done by the
shielding gas.
But due to low deposition rate per hour, TIG process suffers from low
productivity. It is also a fact that penetration depth in normal TIG welding is
low. This means that even for relatively low plate thicknesses like 3.15 mm, 4,
5, 6 and 8 mm several runs are needed to fill the joint.

However in recent years, considerable research has taken place to improve the
productivity of TIG welding. In case high penetration depth can be achieved
even with lower or normal range of welding currents, thin plates can be welded
in one or two passes instead of the large number of passes needed in
conventional TIG welding thereby improving productivity.
OBJECTS OF THE INVENTION
It is therefore, an object of the present invention to propose a novel flux and a
method of TIG welding of titaniumand its alloy (Ti6A14V) for obtaining
increased penetration using the novel flux.
Another object of the present invention is to propose a novel flux and a method
of TIG welding oftitanium and its alloy (Ti6A14V) for obtaining increased
penetration using the novel flux, which uses normal current.
Yet another object of the present invention is to propose a novel flux, which is
cost-effective.
A further object of the present invention is to propose a novel flux and a
method of TIG welding of titanium and its alloy (Ti6A14V) for obtaining
increased penetration using the novel flux which reduces numbers of pass.
A still further object of the present invention is to propose a novel flux and a
method of TIGwelding of titanium and its alloy (Ti6A14V) for obtaining
increased penetration using the novel flux which is eco-friendly.
These and other objects and advantages of the invention will be apparent from
the ensuing description when read in conjunction with the accompanying
drawings.
SUMMARY OF THE INVENTION
The present invention proposes a novel welding flux proposes which
significantly enhances welding penetration during joining by TIG welding of

titanium and its alloy (Ti6A14V) plate. It has been found that the mixture of
magnesium fluoride, calcium oxide and titanium oxide used as flux on the
titanium and its alloy (Ti6A14V) plate results in a significantly higher
penetration.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig 1 shows the mode of application of the flux on the Titanium and its alloy
(Ti6A14V) plate.
DETAILED DESCRIPTION OF THE INVENTION
According to this invention is provided a novel flux and a method of TIG
welding of pure titanium and its alloy (Ti6A14V) for increased penetration,
using the novel flux.
Several materials testing was carried out for their ability to increase
penetration during TIG welding of commercially pure titanium and its alloy
(Ti6A14V) plates. TIG welding was carried out using a mechanized welding
setup. The speed of welding and current are varied for a given base material
thickness and autogenous welding (no external filler was added) was carried
out using bead-on-plate trials.
Mechanized TIG welding using DCEN current using a drooping characteristic
power source (as in normal in TIG welding) was used. Mixture of magnesium
fluoride, calcium oxide and titanium dioxide powder was mixed with acetone
and the thin paste (indicated with number 3 in figure l)with a brush (indicated
with number 2 in figure l)was applied on the 9.5mm titaniumand its alloy
(Ti6A14V) plate(indicated with number 1 in figure 1) which was first cleaned up
and prepared for welding. (Material was formed by mixing magnesium fluoride,
calcium oxide and titanium dioxide powder together).

Magnesium fluoride, calcium oxide and titanium dioxide powder with acetone
forms a paste. The consistency of the paste was adjusted by the use of suitably
adjusting quantities of acetone and the flux. The paste was applied on the plate
surface in 2 variants: one with a thin coating, another with a thick coating,
corresponding roughly to the coating applied once and twice respectively.
Acetone, being a volatile liquid even at room temperature evaporates leaving a
dry coating even prior to welding. On this dry coating, the TIG welding arc is
run autogenously. A run without any flux coating was also run to record the
normal penetration in the absence of a flux. After welding the section was cut
and prepared through metallographic methods and etched to reveal the depth
of penetration.
The magnesium fluoride, is used in 40to 45weight percent, calcium oxide
in 30 to 36weight percent and titanium dioxide in 15 to 18 weight % of the
composition.
The invention will now be explained in greater details, with the help of the
following non-limiting example.
EXAMPLE
5gms of magnesium fluoride was mixed with 4gms of calcium oxide and
2gms of titanium dioxide in acetone, to form a paste.
A titanium - titanium alloy (Ti6A14V) plate of 9.5 mm thickness, was
cleaned and prepared for welding and the paste was applied thereon with a
brush, taking care to cover the junction, and the paste was allowed to dry.
Mechanized TIG welding using TIG power source was used.
After welding, cutting and metallographic preparation, it was found after
etching that the use of mixture of magnesium fluoride, calcium oxide and
titanium dioxide powderas flux had improved penetration significantly

(compared to the TIG welding without flux, and the "single coat" thin layer
coating).
Below is the table comparing the penetration levels obtained with and without
the application of ATIG(Activated tungsten Inert Gas)flux.


WE CLAIM:
1. A flux for TIG welding of pure Titanium and its alloy, comprising
magnesium fluoride in 40 to 45wt%, calcium oxide in 30 to 36wt%
and titanium dioxide in 15 to 18wt%.
2. A method of TIG welding comprising preparing a titanium - titanium
alloy (Ti6A14V) surface for welding, applying a flux on the surface to
form a coating thereon, subjecting the plates with the flux coating to
TIG welding, characterized in that said flux comprises a mixture of
magnesium fluoride, calcium oxide and titanium dioxide.
3. The method as claimed in claim 2, wherein said flux comprises a
mixture of magnesium fluoride powder, calcium oxide powder and
titanium dioxide powder and titanium dioxide powder in acetone.
4. The method as claimed in claim 2, when said flux is applied as a thick
layer.
5. The method as claimed in claim 2, wherein an autogenous TIG welding
carried out with DCEN current. This flux when applied over the plate in
bead on plate test assembly for plate thickness of 9.5mm and welded in
single pass is capable of imparting a penetration of nearly 4mm which is
40% higher than the penetration achieved without the applying the
activating flux.