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Argon Argon
is an inert gas which is used both singularly and in combination with other
gases to achieve desired arc
characteristics for the welding of both ferrous and non-ferrous metals. Almost
all welding processes can use
argon or mixtures of argon to achieve good weldability, mechanical properties,
arc characteristics and productivity.
Argon is used singularly on non-ferrous materials such as aluminum, nickel based
alloys, copper
alloys, and reactive metals which include zirconium, titanium, and tantalum. Argon
provides excellent spray
arc welding stability, penetration and bead shape on these materials. Some short
circuiting arc welding
of thin materials is also practiced. When using ferrous materials, argon is usually
mixed with other gases
such as oxygen, helium, hydrogen, carbon dioxide and/or nitrogen.
The low ionization potential of argon
creates an excellent current path and superior arc stability. Argon
produces a constricted arc column at
a high current density which causes the arc energy to be concentrated
in a small area. The result is a deep
penetration profile having a distinct ”finger like” shape.
Carbon Dioxide
Pure carbon dioxide is not an inert
gas, because the heat of the arc breaks down the CO2 into
carbon monoxide
and free oxygen. This oxygen will combine with elements transferring across the
arc to form oxides
which are released from the weld puddle in the form of slag and scale. Although
CO2 is an active gas
and produces an oxidizing effect, sound
welds can be consistently and easily achieved which are free of
porosity and defects.
Carbon dioxide is widely used for the
welding of steel. Its popularity is due to the common availability and
quality weld performance as well as
its low cost and simple installation. It should be mentioned that low cost
per unit of gas does not automatically
translate to lower cost per foot of weld and is greatly dependent on
the welding application. Factors such
as lower deposition efficiency for CO2 caused
by spatter loss, influence
the final weld cost.
