Tweco 251 Thermal Arc Fabricator - Manual (Page 52)

FABRICATOR 251
OPERATION 4-14 Manual No. 0-4847
4.10 Gas Selection for Gas Metal Arc Welding
Metal Type
Base Plate
Thickness
Filler
Metal
Transfer
Mode
Suggested
Shielding
Gas
Welding
Positions
Comments
Greater than 22
gauge (.030”)
ER70S-X Short
Circuit
100% CO
2
All
Position
Welding
High welding speeds. Good
penetration and pool control.
Greater than 22
gauge (.030”)
ER70S-X Short
Circuit
75% Argon
25% CO2
All
Position
Welding
Suitable for high-current and high-
speed welding.
Greater than 22
gauge (.030”)
ER70S-X Short
Circuit
92% Argon
8% CO2
All
Position
Welding
Higher deposition rates without melt-
through. Minimum distortion and
spatter. Good pool control for out-of-
position welding.
Greater than 10
gauge (1/8”)
ER70S-X Spray
Transfer
92% Argon
8% CO2 or
minimum
80% Argon
20% O2
Flat & HV
Fillet
Good arc stability, weld soundness,
and increasing width of fusion.
Greater than 22
gauge (.030”)
See * below Short
Circuit
Globular
75% Argon
25% CO2
All
Position
Welding
High welding speeds. Good
penetration and pool control.
Applicable for out-of-position welds.
Suitable for high-current and high-
speed welding.
Greater than 22
gauge (.030”)
See * below Short
Circuit
92% Argon
8% CO2
All
Position
Welding
Good coalescence and bead contour.
Good mechanical properties.
Greater than
3/32”
See * below Spray
transfer
92% Argon
8% CO2 or
minimum
80% Argon
20% O2
Flat & HV
Fillet
Reduces undercutting. Higher
deposition rates and improved bead
wetting. Deep penetration and good
mechanical properties.
Greater than 14
gauge (.075”)
See * below Short
Circuit
98% Argon
2% CO2
All
Position
Welding
Good control of melt-through and
distortion. Used also for spray arc
welding. Pool fluidity sometimes
sluggish depending on the base alloy.
Greater than 22
gauge (.030”)
ER308-X
ER309-X
ER316-X Short
Circuit
90% Helium
7.5% Argon
2.5% CO2 or
81% Argon
18% Helium
1 % CO2
All
Position
Welding
Low CO
2
percentages in Helium mix
minimizes carbon pickup, which can
cause intergranular corrosion with
some alloys. Helium improves wetting
action and contour. CO
2
percentages
above 5% should be used with
caution on some alloys.
Greater than
3/32”
ER308-X
ER309-X
ER316-X Spray
Transfer
90% Helium
7.5% Argon
2.5% CO2 or
81% Argon
18% Helium
1 % CO2
Flat & HV
Fillet
Good arc stability. Produces a fluid
but controllable weld pool, good
coalescence, and bead contour.
Minimizes undercutting on heavier
thickness.
Aluminum Greater than 18
gauge (.045”)
ER4043
ER5356 Spray
Transfer
Argon All
Position
Welding
Excellent cleaning action. Provides
more stable arc than helium-rich
mixtures.
* Contact your Filler Metal Supplier for recommended filler metal for the base metal to be welded.
Stainless
Steel
Carbon
Steel
Low Alloy
and High
Alloy Steel
Table 4-4: Gas Selection Chart