How to MIG Weld Structural Steel
Structural steel is a low carbon steel that can be welded with a metal inert gas (MIG) welder more easily than aluminum or titanium. Structural steel with thicknesses greater than 18 gauge can be welded using a flux-cored MIG wire and therefore it does not need a shielding gas to protect the weld. Thinner sheets of structural steel can be MIG-welded with a solid carbon steel wire as long as you also use a shielding gas mixture of argon and carbon dioxide.
Things You'll Need
- Clamps
- Wire brush
- MIG welding machine and torch
- Flux-cored carbon steel MIG wire (E71T-GS)
- Solid carbon steel MIG wire (ER70S-6)
- Shielding gas
- Welder's helmet and gloves
Instructions
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1
Align the structural steel pieces you are welding together and clamp in place to prevent movement while you weld.
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2
Remove rust, paint or dirt from the weld seam by brushing it with a wire brush.
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3
Load your MIG welder with MIG wire suitable to the thickness of the metal you are welding.
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4
Put on your welder's helmet and gloves.
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5
Begin the weld bead by striking an arc along the joint seam. Keep the torch tip less than 1/4 inch from the surface of the metal. Do not touch the torch tip to the metal.
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Hold the torch tip at a 20-degree angle behind vertical if you are push welding the weld bead or at a 20-degree angle forward from vertical if you are pull welding the pieces together.
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Slowly move the torch along the seam in a small circle or zigzag pattern to melt both parent pieces and to mix the molten metal together to form one solid metal sheet. For best results, keep the torch electrode toward the front edge of the weld pool.
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Hold the torch at the end of the weld seam for a few seconds longer to pool the molten metal at the edge and prevent a low point on the weld.
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9
Brush off any excess slag using a wire brush after the weld cools.
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Tips & Warnings
Always weld in a well-ventilated area.
Do not wear loose or combustible clothing while welding. Do not weld near flammable materials.
References
- Photo Credit soudage image by photlook from Fotolia.com
