FIELD OF INVENTION
The present disclosure, in general, relates to a method of method of Tungsten inert
gas welding of Aluminium alloy and to Activated Tungsten inert gas welding of
Aluminium alloy for increased penetration using a novel flux.
BACKGROUND AND PRIOR ARTS
Tungsten inert gas (TIG) welding is a process where parts are joined together by
application of heat generated due to an arc stuck between 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 Tungsten inert gas welding.
Tungsten inert gas welding is most commonly used for metals like Aluminium.
Sheets and plates of Aluminium of low thickness are most commonly welded
using this technique. AC current polarity is the preferred current for welding of
Aluminium. Tungsten inert gas welding is applied to weld Aluminium sheets,
plates, pipes, tubings and castings to be used in various industries like aerospace,
ship building etc.
Aluminium materials up to 3mm thick can be welded by the single pass
autogenous Tungsten inert gas weld method. However, the penetration power is
least in case of Tungsten inert gas welding. Therefore, materials of greater
thickness require multiple pass welding for joining which makes the process less
productive. 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 Tungsten inert gas 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. However, in recent years, considerable research has taken
place to improve the productivity of Tungsten inert gas 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 Tungsten inert gas welding thereby
improving productivity.
All welding processes rely on either gas shielding or slag shielding (produced
from a welding flux) or a combination thereof. Thus, processes like 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. As mentioned earlier,
there is no need to use a flux system in conventional Tungsten inert gas welding.
But due to low deposition rate per hour, Tungsten inert gas process suffers from
low productivity. It is also a fact that penetration depth in normal Tungsten inert
gas 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.
Activated Flux Tungsten inert gas welding is a unique joining process and is also
called fluxed zone Tungsten inert gas. The use of activated flux in TIG helps to
improve weld penetration. ATIG aids in the increase of penetration of thick
materials by one or a couple of passes than multiple passes required in
conventional Tungsten inert gas welding.
There have been studies on achieving greater penetration during Tungsten inert
gas welding, however they have not been able to provide a simple and cost-
effective solution to increase welding penetration. Lucas, W and Howse, D, 1996
have shown that in Activated Flux Tungsten inert gas welding, constriction of the
electric arc and reversal of Marangoni convection were found to be the
mechanisms for deeper penetration. However, the study does not elaborate about
novel fluxes which may also lead to deeper welding penetration, with greater cost
efficiency. P. C. J. Anderson and R. Wiktorowicz, 1996 in another study have

developed an in-house Activated-flux tungsten inert gas (A-TIG) welding, that
increases the depth of penetration in single pass welding. However, their process
is limited to being a model and not involving any flux for depth penetration.
An example in the art is included in US7896979B2, which discloses an activating
flux for welding stainless steel includes: from 25 to 40 weight percent of titanium
dioxide (TiO2); from 25 to 30 weight percent of chromium oxide (Cr2O3); from 10
to 30 weight percent of silicon dioxide (SiO2); from 10 to 15 weight percent of
molybdenum disulphide (MoS2); and from 5 to 15 weight percent of molybdenum
trioxide (MoO3), which are active additive materials. A welding rod or wire
includes a welding material and an activating flux. The activating flux layer is
provided on or in the welding rod or wire and is formed as an outer layer or a core
portion of the welding rod or wire. However, the disclosed invention requires the
use of several compounds and is directed particularly for welding of stainless
steel.
Another example in the art is included in US8097831B2 which discloses a method
of welding of two metal parts each having a predetermined thickness with a
penetrating welding flux to be applied on an extra thick zone of the metal parts
prior to the Tungsten inert gas welding step. However, the invention is not
optimized for increasing welding penetration on materials with uniform thickness
or low thickness.
A further example in the art in included in US8097826B2 which discloses a
Penetration Enhancing Activating Flux (PEAF) in paste form for autogenous
Tungsten inert gas welding of austenitic stainless steels adapted for ready
application with a brush on top weld surface prior to conducting autogenous
Tungsten inert gas welding to favor single weld pass, of austenitic stainless steels
of AISI 304LN and AISI 316LN varieties with weld bead penetration up to a
section thickness of 12 mm. However, the flux is not optimized for use with
Aluminum alloy.
Accordingly, there is a clear felt need in the art for providing a simple,
economical and efficient activating flux for increased welding penetration during
Tungsten inert gas welding of Aluminium alloy.

Keywords
Tungsten inert gas welding- TIG welding, Activated Tungsten inert gas welding-
ATIG
OBJECTS OF THE INVETION
It is therefore an object of the present invention to propose a method of TIG
welding of aluminium for obtaining increased penetration using a novel flux.
Another object of the present invention is to propose a method of TIG welding of
aluminium for obtaining increased penetration using a novel flux which uses
normal current, i.e. AC current.
Yet Another object of the present invention is to propose a method of TIG
welding of aluminium for obtaining increased penetration using a novel flux
which reduces numbers of pass.
Further object of the present invention is to propose a method of TIG welding of
aluminum for obtaining increased penetration using a novel flux which is eco-
friendly.
SUMMARY OF THE INVENTION
In a conventional TIG welding process, especially for aluminum, there is usually
no need to use a flux system, but due to low deposition rate per hour, the
conventional TIG process suffer from low productivity along with low penetration
depth. Thus, even for relatively low plate thickness like 3.15 mm, 4, 5, 6 and 8
mm several passes are needed to fill the joint.
The present invention relates to a method of TIG welding for aluminium plates of
thickness 3-5mm in a single pass using a novel flux of silicon dioxide and acetone
in paste form. The steps underlying the present invention are as follows- selecting
Aluminium plate(s) (1) of thickness 3-5 mm and suitably clamped; application of

flux paste (3) with the help of a brush (2) to the Aluminium plate along the length
wherein width of fluxed portion is 15mm; carrying out semi-automatic TIG
welding process over flux applied Aluminium plate in a single pass. The welding
parameters are as follows- Peak Current (average value): 110 Amps, Welding
Speed (average value): 100 mm/min and Arc Length (average value): 1.5 mm.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
It is to be noted, however, that the appended drawing(s) illustrate only typical
embodiments of the present subject matter and are therefore not to be considered
for limiting of its scope, for the invention may admit to other equally effective
embodiments. The detailed description is described with reference to
accompanying figures. Some embodiments of system or methods in accordance
with embodiments of the present subject matter are now described, by way of
example, and with reference to accompanying figures, in which:
Fig. 1: Illustrates a mechanized welding setup wherein (1) refers to
Aluminium test plate of 5 mm thickness, (2) refers to applicator brush and (3)
refers to the thin flux paste composed of silicon dioxide and acetone.
DETAILED DESCRIPTION OF THE INVENTION
At the very outset of the detailed description, it may be understood that the
ensuing description only illustrates a form of this invention. However, such a form
is only exemplary embodiment, and without intending to imply any limitation on
the scope of this invention. Accordingly, the description is to be understood as an
exemplary embodiment and teaching of invention and not intended to be taken
restrictively.
Throughout the description and claims of this specification, the phrases
“comprise” and “contain” and variations of them mean “including but not limited
to”, and are not intended to exclude other moieties, additives, components,
integers or steps. Thus, the singular encompasses the plural unless the context

otherwise requires. Wherever there is an indefinite article used, the specification is
to be understood as contemplating plurality as well as singularity, unless the
context requires otherwise.
Features, integers, characteristics, compounds, chemical moieties or groups
described in conjunction with an aspect, embodiment or example of the invention
are to be understood to be applicable to any other aspect, embodiment or example
described herein unless incompatible therewith. All the features disclosed in this
specification (including any accompanying claims, abstract and drawings), and/or
all the steps of any method or process so disclosed, may be combined in any
combination, except combinations where at least some of such features and/or
steps are mutually exclusive. The invention is not restricted to the details of any
foregoing embodiments. The invention extends to any novel one, or any novel
combination, of the features disclosed in this specification including any
accompanying claims, abstract and drawings or any parts thereof, or to any novel
one, or any novel combination, of the steps of any method or process so disclosed.
The reader's attention is directed to all papers and documents which are filed
concurrently with or before this specification in connection with this application
and which are open to public inspection with this specification, and the contents
of all such papers and documents are incorporated herein by reference. Post filing
patents, original peer reviewed research paper may be published.
The following descriptions of embodiments and examples are offered by way of
illustration and not by way of limitation.
Unless contraindicated or noted otherwise, throughout this specification, the terms
“a” and “an” mean one or more, and the term “or” means and/ or.
The present invention relates to a method of TIG welding for aluminum using a
novel flux comprising the steps of- preparation of aluminium surface to qualify
for welding; application of flux using a brush and completion of TIG welding.
The unique feature of the present invention is the novel welding flux which
significantly enhances welding penetration during joining by TIG welding of
aluminium plate. It has been found that the mixture of silicon dioxide with

acetone used as flux on the aluminum plate results in a significant change in
penetration.
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 AC current using a drooping characteristic power
source (as in normal in TIG welding) was used. Mixture of silicon dioxide was
mixed with acetone and the thin paste (3) with a brush (2) was applied on the 5
mm aluminium plate (1), wherein the flux material comprises of silicon dioxide.
Silicon dioxide powder with acetone forms a paste. The consistency of the paste
was adjusted using 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. After welding, cutting and metallographic preparation, it was found
after etching that the use of mixture of silicon dioxide powder as flux had
significant effect on penetration compared to the TIG welding without flux, which
has been elaborated in Table 1.


The method comprising the steps of: selecting Aluminium plates (1) of thickness
3-5mm which are then suitably clamped to avoid distortion during welding
process; application of powder flux (active flux) paste (acetone added) (3) with
the help of a brush (regular paint/ drawing brush) (2) to the Aluminium plate
along the length (width of fluxed portion is 15mm); semi-automatic TIG welding
process is carried out over flux portion, along the length of the plate.
The welding parameters are as follows-

This flux applied over the plate in bead on plate test assembly for plate thickness
of 5mm is welded in a single pass to impart a penetration of nearly 2 to 3mm.
Now, the crux of the invention is claimed implicitly and explicitly through the
following claims.

We Claim:
1. A method of TIG welding for aluminium alloy using a novel flux imparting an
increase in penetration of welded metal, said method comprising the steps of:
a) selecting Aluminium plates of thickness 3-5 mm (1) and suitably clamped;
b) applying flux paste (3) with the help of a brush (2) to the Aluminium plate
along the length wherein width of fluxed portion is 15mm;
c) carrying out semi-automatic TIG welding process over flux applied
Aluminium plate in a single pass;
characterised in that the flux comprises a mixture of silicon dioxide with liquid
acetone in the form of a paste.
2. The method as claimed in claim 1, wherein the welding is performed in an
average speed of 100 mm/ min at an average 110 amps peak current, with an
average arc length of 1.5 mm.
3. The method as claimed in claim 1, wherein said flux is applied to plate thickness
of preferably 5mm.
4. The method as claimed in claim 1, wherein the flux has nearly 100% pure form
silicon dioxide.
5. The method as claimed in claim 1, wherein flux of 5g/m2 density in a thick layer
is used for carrying out welding.
6. The method as claimed in claim 1, wherein the welding is carried out with AC
current with voltage 12 V.