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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. |
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. |