| MIG Gases (Short Circuit Transfer) | ||
| Metal | Gas | Advantages |
| Carbon Steel | 75% argon + 25% carbon dioxide | Less than 1/8” thick -High welding speed -No burn-through -Minimum distortion and spatter |
| 75% argon + 25% carbon dioxide | More than 1/8” thick -Minimum spatter -Clean weld appearance -Good puddle control in vertical and overhead positions -Both GMAW and FCAW | |
| carbon dioxide | -Deeper penetration -Faster welding speeds -Both GMAW and FCAW | |
| Stainless Steel | 90% helium + 7.5% argon + 2.5% carbon dioxide | -No effect on corrosion resistance -Small heat-affected zone -No undercut -Minimum distortion |
| Low Alloy Steel | 60-70% helium + 25-35% argon + 4-5% carbon dioxide | -Minimum reactivity -Excellent toughness -Excellent arc stability, wetting characteristics and bead contour -Little spatter. |
| 75% argon + 25% carbon dioxide | -Fair toughness -Excellent arc stability, wetting characteristics and bead contour -Little spatter | |
| Aluminum, Copper, Magnesium, Nickel and their alloys | Argon & argon + helium | -Satisfactory on sheet metal -Argon-helium preferred on material over 1/8” |
| MIG Gases (Spray Transfer) | ||
| Metal | Gas | Advantages |
| Carbon Steel | Argon + 1-5% oxygen | -Improved arc stability -More fluid and controllable weld puddle -Good bead contour -Minimum undercut -Higher speeds than pure argon |
| Argon + 3-10% carbon dioxide | -Good bead shape -Minimum spatter -Reduced chance of cold lap -Flat/horizontal position only |
|
| Low Alloy Steel | Argon + 2% oxygen | -Minimum undercut -Good toughness |
| Aluminum | Argon | Up to 1" thick -Best metal transfer and arc stability -Least spatter |
| 35% argon + 65% helium | Up to 1" thick -Higher heat input than pure argon -Improved fusion characteristics with 5XXX series Al-Mg alloys |
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| 25% argon + 75% helium | Over 3” thick -Highest heat input -Minimum porosity |
|
| Magnesium | Argon | -Excellent cleaning action |
| Stainless Steel | Argon + 1% oxygen | -Improved arc stability -More fluid and controllable weld puddle -Good bead contour -Minimum undercut on heavier stainless steels |
| Argon + 2% oxygen | -Better arc stability & welding speed than 1% oxygen mixture for thinner stainless steels | |
| Copper, nickel and their alloys | Argon | -Good wetting characteristics -Decreased fluidity of weld metal for thickness' up to 1/8” |
| Argon + helium | -Higher heat inputs to 50 and 75% helium mixtures offset high heat dissipation of heavier gauge materials | |
| Titanium | Argon | -Good arc stability -Minimum weld contamination -Inert gas backing is required to prevent air contamination on back of weld |
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