7
Binary (2) Shielding Gas Mixtures
Argon-Oxygen The
addition of srnall amounts of 02 to argon
greatly stabilizes the weld arc, increases the filler metal droplet
rate, lowers the spray arc transition
current, and improves wetting and bead shape. The weld puddle is more
fluid and stays molten longer allowing
the metal to flow out towards the toe of the weld. This reduces
undercutting and helps flatten the weld
bead. Occasionally, small oxygen additions are used on non- ferrous
applications. For example, it’s
been reported by NASA that .1% oxygen has been useful for arc stabilization
when welding very clean aluminum plate.
Argon-1% O2
– This mixture is primarily used for spray transfer
on stainless steels. One percent oxygen is usually
sufficient to stabilize the arc, improve the droplet rate, provide coalescence
and improve appearance.
Argon-2% O2
– This mixture is used for spray arc welding on
carbon steels, low alloy steels and stainless steels.
It provides additional wetting action over the 1% 02
mixture. Mechanical properties and corrosion resistance
of welds made in the 1 and 2% 02 additions
are equivalent. Argon-5%
O2 –
This mixture provides a more fluid but controllable weld pool. It is the most
commonly used argon-oxygen
mixture for general carbon steel welding. The additional oxygen also permits higher
travel speeds.
