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Shape and depth of Penetration
The shape and depth of penetration of beads obtained with various shielding gases using DCEP polarity
Some shielding gas selections for GMAW of various metals
| Metals | Gases % | Uses and results |
| Aluminum | Ar
50Ar-50He 25Ar-75He He |
Good transfer, stable arc, little spatter, Removes oxides
Hot arc – 3/8” to 3/4” (10mm to 19mm) thickness, Remove oxides. Hot arc, less porosity, removes oxides – 1/2” to 1” (13mm to 25mm) Hotter, more gas; 1/2” (13mm) and up. Removes oxides. |
| Magnesium | Ar
75He-25Ar |
Good cleaning.
Hotter, less porosity, removes oxides. |
| Copper (deox.) | 75He-25Ar
Ar |
Preferred. Good wetting, hot. For thinner materials. |
| Carbon steel | CO2
Ar-2 O2 Ar-5 O2 75Ar-25CO2 50Ar-50CO2 |
Short circuiting arc: high quality, low current, out-of-possition, medium spatter
Globular arc: fast, cheap, spattery, deep penetration. Fast, stable, good bead shape, little undercut, fluid weld pool. Short circuiting arc: fast, no melt-throgh, little distortion and spatter. Short circuiting arc: deep penetration, low spatter. |
| Low-alloy steel | Ar-2 O2 | Removes oxides, eliminates undercut, good properties. |
| High-strength steels | 60He-35Ar-5CO2
75Ar-25CO2 |
Short circuiting arc: stable arc, good wetting and bead contour, little spatter. Good impacts.
Short circuiting arc: same except low impact. |
| Stainless steel | Ar-1 O2 Ar-5 O2
90He-7 1/2 Ar-2 1/2 CO2 |
No undercutting. Stable arc, fluid weld, good shape. More stable arc.
Short circuiting arc: small heat-affected zone, no undercut, little warping |
| Nickel, monel | Ar | Good wetting – decreases fluidity. |
| Inconel | Ar-He | Stable arc on thinner material. |
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Shape and depth of Penetration
The shape and depth of penetration of beads obtained with various shielding gases using DCEP polarity
Some shielding gas selections for GMAW of various metals
| Metals | Gases % | Uses and results |
| Aluminum | Ar
50Ar-50He 25Ar-75He He |
Good transfer, stable arc, little spatter, Removes oxides
Hot arc – 3/8” to 3/4” (10mm to 19mm) thickness, Remove oxides. Hot arc, less porosity, removes oxides – 1/2” to 1” (13mm to 25mm) Hotter, more gas; 1/2” (13mm) and up. Removes oxides. |
| Magnesium | Ar
75He-25Ar |
Good cleaning.
Hotter, less porosity, removes oxides. |
| Copper (deox.) | 75He-25Ar
Ar |
Preferred. Good wetting, hot. For thinner materials. |
| Carbon steel | CO2
Ar-2 O2 Ar-5 O2 75Ar-25CO2 50Ar-50CO2 |
Short circuiting arc: high quality, low current, out-of-possition, medium spatter
Globular arc: fast, cheap, spattery, deep penetration. Fast, stable, good bead shape, little undercut, fluid weld pool. Short circuiting arc: fast, no melt-throgh, little distortion and spatter. Short circuiting arc: deep penetration, low spatter. |
| Low-alloy steel | Ar-2 O2 | Removes oxides, eliminates undercut, good properties. |
| High-strength steels | 60He-35Ar-5CO2
75Ar-25CO2 |
Short circuiting arc: stable arc, good wetting and bead contour, little spatter. Good impacts.
Short circuiting arc: same except low impact. |
| Stainless steel | Ar-1 O2 Ar-5 O2
90He-7 1/2 Ar-2 1/2 CO2 |
No undercutting. Stable arc, fluid weld, good shape. More stable arc.
Short circuiting arc: small heat-affected zone, no undercut, little warping |
| Nickel, monel | Ar | Good wetting – decreases fluidity. |
| Inconel | Ar-He | Stable arc on thinner material. |
