No. 6555 Songze Avenue, Chonggu Town, Qingpu District, Shanghai, China
What types of metals can be welded using MIG welding?
Introduction: The Versatility of MIG Welding in Sheet Metal Fabrication
Hi, I’m Barry Zeng, a manufacturing engineer at Shanghai Yunyan Prototype & Mould Manufacture Factory. In the world of Sheet Metal Fabrication, one question I hear constantly is: “What metals can I weld with MIG?” The short answer is: a lot. MIG (Metal Inert Gas) welding, also known as GMAW, is one of the most versatile processes in Sheet Metal Fabrication. It can handle everything from everyday mild steel to exotic alloys like titanium. However, each metal requires specific shielding gases, filler wires, and parameter adjustments. In this guide, I’ll walk you through the most common weldable metals, their challenges, and how to get perfect results. Whether you’re working on structural steel, stainless enclosures, or aluminum prototypes, understanding MIG’s capabilities will make your Sheet Metal Fabrication projects faster and stronger.
Chapter 1: Carbon Steel and Low-Alloy Steel – The Workhorses
Carbon steel is the most common metal welded with MIG. In Sheet Metal Fabrication, mild steel (e.g., A36, Q235) is used for brackets, frames, enclosures, and automotive panels. MIG welding of carbon steel is straightforward:
- Shielding gas: 75% Ar / 25% CO₂ (C25) is the standard. It provides good arc stability, minimal spatter, and deep penetration.
- Filler wire: ER70S‑6 is the most common. It contains deoxidizers (silicon, manganese) to handle minor surface contamination.
- Parameters: For 1–3 mm sheet, use 16–18V, wire feed speed 120–180 IPM (0.8–1.0 mm wire). Thicker plates (6–10 mm) require 19–22V and 200–300 IPM.
- Applications: Structural steel frames, machine bases, exhaust systems, and general repair.
One tip: for thin carbon steel (<1.5 mm), reduce voltage and wire feed to avoid burn‑through. You can also use 90% Ar / 10% CO₂ for less spatter on thin sheets.
Chapter 2: Stainless Steel – Precision and Prevention
Stainless steel (304, 316) is widely used in Sheet Metal Fabrication for food equipment, medical devices, and chemical tanks. MIG welding stainless is possible but requires more care than carbon steel. Key points:
- Shielding gas: Tri‑mix (90% He / 7.5% Ar / 2.5% CO₂) or 98% Ar / 2% CO₂ are preferred. Avoid pure CO₂ – it causes carbon pickup and reduces corrosion resistance.
- Filler wire: ER308L for 304 stainless, ER316L for 316. The “L” means low carbon to prevent intergranular corrosion.
- Parameters: Lower heat input is critical to prevent warping and carbide precipitation. Use voltage 18–20V, wire feed 150–200 IPM for 2 mm sheet. Keep travel speed high.
- Back purging: For pipe or closed sections, back purge with argon to prevent sugaring (oxidation on the root side).
- Applications: Kitchen equipment, pharmaceutical vessels, architectural railings.
If you see discoloration (blue or gray), you’ve overheated the stainless. Reduce voltage and increase travel speed.
Chapter 3: Aluminum – Lightweight but Demanding
Aluminum is increasingly popular in Sheet Metal Fabrication for lightweight enclosures, heat sinks, and automotive parts. MIG welding aluminum is trickier due to its oxide layer and high thermal conductivity. Here’s how to succeed:
- Shielding gas: 100% argon. Never use CO₂ or argon‑CO₂ mixes – they cause severe oxidation and porosity.
- Filler wire: 4043 (general purpose) or 5356 (higher strength, better corrosion resistance). Use 1.2 mm wire for thicker sections; 0.8–1.0 mm for thin sheet.
- Equipment: Use a spool gun or push‑pull gun to avoid wire feeding problems (aluminum wire is soft and tangles easily). A pulse MIG welder is highly recommended for thin aluminum.
- Parameters: For 2 mm aluminum, set voltage 20–22V, wire feed 300–400 IPM, and use spray transfer. Pulse MIG allows lower heat input and better control.
- Cleaning: Remove the aluminum oxide layer with a stainless steel brush (dedicated to aluminum only). Wipe with acetone.
- Applications: Boat hulls, fuel tanks, trailer ramps, electronic enclosures.
Aluminum MIG is not for beginners – consider TIG for thin aluminum (<2 mm). But with pulse MIG, you can achieve excellent results.
Chapter 4: Copper, Brass, and Bronze – Specialized Applications
Copper and its alloys are less common in general Sheet Metal Fabrication but appear in electrical components, heat exchangers, and decorative work. MIG welding is possible but requires specific fillers and gases:
- Copper (C110): Use deoxidized copper wire (ERCu). Shielding gas: 100% argon. Preheat thick copper to 300–500°F to avoid cracking. High thermal conductivity demands high heat input – use voltage 24–28V.
- Brass (C260, C280): More difficult due to zinc vaporization (produces white fumes). Use silicon bronze wire (ERCuSi‑A) or aluminum bronze. Shielding gas: 100% argon. Ventilate well – zinc fumes are toxic.
- Silicon bronze: Often used for MIG brazing (joining dissimilar metals or thin sheets without melting base metal). Gas: 100% argon. Low heat input, good for galvanized steel.
- Applications: Electrical bus bars, plumbing fittings, architectural trim, artistic sculptures.
For most shops, TIG is preferred for copper and brass due to better control, but MIG can work with proper technique.
Chapter 5: Magnesium, Titanium, and Nickel Alloys – Exotic Metals
Advanced Sheet Metal Fabrication sometimes involves exotic alloys used in aerospace, motorsports, and chemical processing. MIG welding is possible but demands rigorous preparation and equipment:
- Magnesium alloys (AZ31B): Lightest structural metal. Use AZ61A or AZ92A filler. Shielding gas: 100% argon. Must clean oxide and avoid moisture (risk of fire). Preheating is critical. Harder than aluminum – requires pulse MIG.
- Titanium (Grade 2, 5): Excellent strength‑to‑weight. Must use pure argon shielding with trailing shield (titanium reacts with oxygen at high temperature). Any contamination causes embrittlement. Use ERTi‑2 filler. Typically TIG is preferred, but MIG can be used for thick sections with special equipment.
- Nickel alloys (Inconel, Monel, Hastelloy): High‑temperature and corrosion‑resistant. Use matching filler (e.g., ERNiCr‑3 for Inconel 625). Shielding gas: 100% argon or argon‑helium mix. Low heat input, interpass temperature control. Common in chemical plants and jet engines.
These materials are not DIY‑friendly. Leave them to specialists with the right equipment (pulse MIG, gas shielding systems, and post‑weld heat treatment).
Chapter 6: Dissimilar Metal Welding – What Works and What Doesn’t
Sometimes Sheet Metal Fabrication requires joining different metals. MIG can join certain combinations:
- Carbon steel to stainless steel: Use ER309L filler. Shielding gas: 90% Ar / 10% CO₂. Common in exhaust systems.
- Steel to aluminum: Not directly weldable with MIG – the brittle intermetallic layer causes cracking. Use mechanical fasteners, brazing, or friction welding instead.
- Steel to copper: Use silicon bronze filler (MIG brazing). Good for electrical connections.
- Aluminum to copper: Very difficult; avoid direct welding.
Always consult filler wire manufacturer recommendations before attempting dissimilar metal welds.
Chapter 7: Case Study – Fabricating a Stainless Steel Food Conveyor Frame
A client needed a 304 stainless steel frame for a food processing conveyor. They attempted MIG with C25 gas – the welds were porous and corroded after cleaning. We switched to 98% Ar / 2% CO₂, used ER308L wire, and set voltage to 19V. The result: clean, golden‑colored welds passing the dye penetrant test. The frame has been in service for 2 years with no issues. This shows that with the right gas and filler, MIG welding of stainless steel is highly reliable.
Chapter 8: Quick Reference – Gas and Filler Wire Selection
| Base Metal | Shielding Gas | Filler Wire |
|---|---|---|
| Mild Steel | 75% Ar / 25% CO₂ | ER70S‑6 |
| Stainless Steel (304) | 98% Ar / 2% CO₂ | ER308L |
| Aluminum (5052/6061) | 100% Ar | 4043 or 5356 |
| Copper | 100% Ar | ERCu |
| Silicon Bronze | 100% Ar | ERCuSi‑A |
| Magnesium | 100% Ar | AZ61A |
Conclusion: Match the Metal to the Process
MIG welding is incredibly versatile, but success depends on matching the right shielding gas, filler wire, and parameters to the base metal. From common carbon steel to exotic titanium, Sheet Metal Fabrication projects can benefit from MIG’s speed and efficiency. When in doubt, test on coupons and consult a welding engineer. We MIG weld carbon steel, stainless, aluminum, and copper alloys daily. Send me your project details – I’ll recommend the best welding approach and provide a free quote.
👇 Need Assistance with MIG Welding for Your Sheet Metal Project?
Tell me your material, thickness, and application. I’ll recommend the best MIG process, gas, and filler — and provide a free DFM report and quote within 24 hours.
📞
Call Barry
Direct engineering line
(I answer welding questions)
+86 138 1894 4170
🌐
Visit Our Site
Download “MIG Welding Parameters Chart”
(Gas/wire guide for common metals)
Not sure which filler wire or gas to use? Just say: “Barry, here’s my material – what MIG setup do I need?” I’ll guide you.
🔥 MIG Welding – Master Any Metal in Sheet Metal Fabrication 🔥
P.S. Mention “MIG guide” when you email, and I’ll send you a printable MIG parameter wall chart for carbon steel, stainless, and aluminum.
Barry Zeng
Senior Manufacturing Engineer, Shanghai Yunyan Prototype & Mould Manufacture Factory
(10+ years MIG welding metals from mild steel to exotic alloys – let me help you choose the right process.)
