Study of Shielded Gases For MIG Welding
Study of Shielded Gases For MIG Welding
Study of Shielded Gases For MIG Welding
Abstract
Protecting shielding gases are inert or semi-inert gasses that are regularly utilized in few
welding forms, mostly in gas metal arc welding and gas tungsten arc welding (GMAW and
GTAW, more prevalently known as MIG and TIG, respectively). Their purpose is to shield the
weld region from oxygen, and water vapour. Contingent upon the materials being welded,
these air gases can diminish the quality of the weld or make the welding more troublesome.
Other arc welding forms use different strategies for shielding the weld from the atmosphere as
well shielded metal arc welding, for instance, utilizing a cathode secured as a part of a flux
that creates carbon dioxide when consumed, a semi-inert gas that is an adequate shielding
gas for welding steel. This paper deals with various forms of shielded gases used in GMAW
and how composition of shielding gas chosen for GMAW can affect welding operation.
Keywords: Shielding gases, water vapor, weld bead, spatter, welding fumes
JoMME (2016) 6-10 © STM Journals 2016. All Rights Reserved Page 6
Shielded Gases for MIG Welding Kikani Pratik
Fig. 2: Part Welded with Argon and Argon + CO2 Shielding Gas.
JoMME (2016) 6-10 © STM Journals 2016. All Rights Reserved Page 7
Journal of Materials & Metallurgical Engineering
Volume 6, Issue 1
ISSN: 2231-3818(online), ISSN: 2321-4236(print)
Effect of Shielding Gas Composition on 1. Filler metal deposition rate and efficiency.
Welding Operation 2. Spatter control and post weld cleaning.
Shielding gas composition is chosen for 3. Bead profile and over welding.
GMAW can affect welding operation in seven 4. Bead penetration, potential for burn-
key ways [6]: through.
JoMME (2016) 6-10 © STM Journals 2016. All Rights Reserved Page 8
Shielded Gases for MIG Welding Kikani Pratik
Single-wire GMAW can exceed deposition Bead Profile and Over Welding
rates of 6–7 kg per hour at 100% duty cycle. A CO2 shielded weld bead has a tendency to
Argon content should be 85% or more to have a convex shape, which adds to over
accomplish spray transfer. In some cases, welding; this increases welding cost. Argon-
instead of using a conventional argon/carbon based blends offer great globule shaped
dioxide or argon/oxygen blend, using a control, which can decrease over welding. In
helium-enhanced argon blend may increase view of the physical attributes of a CO2
weld metal deposition rates up to 15%. shielded arc and the weld puddle delivered,
CO2 can create convex bead shape. Argon
Cathode testimony productivity is connected blends tend to create a level bead face, which
specifically to the welding scatter level. High- delivers adequate support, however it
argon mixes commonly deliver the best results decreases over welding.
in spray transfer. Enhanced statement
effectiveness likewise can be a component of Optimized bead shape depends upon filler
choosing the right welding parameters. metal diameter. Control of weld bead size
becomes difficult in larger wire size. A
Spatter Control and Post-weld Cleaning curiously large weld bead can increment
By using argon, weld spatter can be decreased welding costs by no less than 50%. Filler
in case of conventional power supplies. Arc metal type and size is based on necessities of
stability can be improved by argon as it has the application.
low ionization. By utilizing argon based
protecting gases, spatter can be lessened much Bead Penetration, Potential for Burn-
more. You can expand the working current and through
voltage by 10% or increasingly while as yet Welding characteristics play an important role
keeping up spatter control. while welding thin material. One normal for
pure CO2 is that it results in expanded weld
In the event that one can utilize spray arc pool vitality when contrasted with an argon/
exchange, for the most part the argon level CO2 mix. By controlling the blend’s CO2
ought to be 85% or more. Pulsed spray transfer content, you can control blaze through and
with a 95% argon mix commonly will yield increment welding efficiency. Argon/ CO2
the most minimal spatter levels when welding mixes can be used in the 85 to 95% reach to
plain carbon steel. A weld spatter can diminish minimize blaze through. To accomplish a good
by three-section mix of argon, helium, and welding penetration, pure CO2 can be used.
carbon dioxide. Penetration profile can be affected by
operating current, filler metal, and gas
As a rule, GMAW is a without slag process, composition. High percentage of CO2 can be
yet slag islands still are basic on the bead used for deep penetration.
surface. Powder and paint won't hold fast to
these silicon stores. Low shielding gas Out-of-Position Weldability
reactivity can diminish these surface residuals. Shielding gases with grater reactivity, which
In case one is worried about slag-island use more CO2 or O2 will increase weld pool
develop along the edge of the weld dot, work fluidity. For out of position work, this may
just with appropriately cleaned base material force to use slower wire feed rates, which will
JoMME (2016) 6-10 © STM Journals 2016. All Rights Reserved Page 9
Journal of Materials & Metallurgical Engineering
Volume 6, Issue 1
ISSN: 2231-3818(online), ISSN: 2321-4236(print)
decrease productivity. Metal transfer selection and efficiency, spatter control and post weld
is a critical thing when trying to improve out cleaning, bead profile and over welding, bead
of position control. High argon blends with penetration, potential for burn-through, out-of-
low reactivity generally performs well. position weldability, welding fume generation
rates, weld metal mechanical properties etc.
Welding Fume Generation Rates
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