Dual shield welding is a great option for welders seeking a technique that delivers deep penetration, high deposition rates, and consistently clean welds. This welding method combines flux-cored arc welding with an external shielding gas. This pairing produces stronger, more reliable welds across various applications, from structural steel fabrication to heavy construction. Below, we'll look at how dual shield welding works and how to get started.
What is Dual Shield Welding?
Dual shield welding is a flux-cored arc welding (FCAW) process that uses two forms of protection to produce high-quality welds: a flux-cored wire and an external shielding gas. The "dual shield" name comes directly from this two-layer protection system.
The slag generated by the flux core in the dual shield wire protects the weld pool as it cools, while the shielding gas protects the welding arc from atmospheric contamination. Both work together to produce fewer defects, higher weld quality, and stronger welds compared to many other welding techniques.
Unlike self-shielded flux-cored welding, which uses only the flux-cored electrode for protection, dual-shield welding adds an external shielding gas to the process, typically carbon dioxide or a mixed gas.
Check out our blog, "What is Flux in Welding", to learn more about flux.
Dual Shield Welding vs. Other Welding Methods
Dual Shield Welding
Dual-shield welding uses a flux-cored electrode and an external shielding gas to protect the weld pool. It's known for its high deposition rates, deep penetration, and strong weld quality on heavier materials. Dual-shield welding is considered the best process for structural and construction work.
Stud Welding
Stud welding uses an electric arc to fuse a metal stud or fastener directly onto a base metal surface. This is a quick welding process that is specifically designed for attaching fasteners in structural steel and manufacturing applications. While dual shield welding can be used almost anywhere, stud welding is highly specialized.
Tack Welding
Welders use tack welding as more of a setup process than a finishing process. It uses short, temporary welds to hold metal parts in position before the final weld is applied. Using dual shield as your final welding process often means that tack welding is part of the prep work that comes before it.
Fusion Welding
This type of welding involves joining metal by melting the base metal itself, with or without using filler material. Fusion welding is a broad category encompassing various welding techniques and is best suited for thinner materials that require precise heat control. Dual-shield welding typically outperforms fusion welding on thicker base metals, where deep penetration and high deposition rates are priorities.
Spot Welding
Spot welding uses electrical resistance rather than an arc to generate heat, fusing metal surfaces at a single localized point without a filler wire. It produces permanent, dot-like welds and is built for high-volume, repetitive joining of thin sheet metal. It's fast and consistent in the right setting, but lacks the versatility and penetration of dual-shield welding.
| Welding Method | Process Type | Shielding Method | Best For |
| Dual Shield Welding | Flux-cored arc welding | Flux core and external shielding gas | Heavy fabrication, structural steel, construction |
| Stud Welding | Arc welding | None required | Fastener attachment, structural steel |
| Tack Welding | Temporary arc welding | Varies by process | Pre-weld alignment and positioning |
| Fusion Welding | Various | Varies by process | Thin materials, precision joining |
| Spot Welding | Resistance welding | None required | High-volume sheet metal production |
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Step-by-Step Guide: How to Dual Shield Weld
Step 1: Set Up Your Equipment
Always begin with the proper setup. Make sure to load your dual shield wire onto the spool and feed it through the welding machine according to the manufacturer's instructions. Ensure that the shielding gas supply is connected and all connections are secure before powering up the machine. Put on your full PPE before you go any further, including a welding hood and welding lenses that meet the requirements for flux-cored arc welding.
Step 2: Prepare Your Base Metal
The base metal needs to be cleaned completely before welding. Any dirt, mill scale, rust, or moisture can adversely affect the weld and cause porosity. Make sure to grind or wire brush the weld zone to achieve a clean metal surface. Also, make sure your workpiece is secured and positioned correctly for the fillet weld or joint you're running.
Step 3: Set Your Parameters
Adjust your wire speed and shielding gas flow before you start welding. Wire speed controls your deposition rate and arc stability; use the wire's recommended settings for your material thickness as a starting point. Adjust your shielding gas flow rate to maintain consistent coverage over the weld pool throughout the welding process. Incorrect parameters are the most common cause of poor weld quality in dual shield welding, so take the time to get this right before you run your first bead.
Step 4: Strike the Arc and Start the Weld Process
After adjusting all parameters and wearing your PPE, position your flux-cored electrode at the start of the weld joint and strike the arc. It's important to maintain a consistent travel speed and keep the electrode angle steady to get an even weld bead with good penetration. Pay attention to the weld puddle, as the puddle tells you what the weld is doing. If there is too much spatter or the arc is unstable, stop and adjust your wire speed or shielding gas flow before continuing.
Step 5: Clean and Inspect the Weld
Once the weld bead is complete, dual-shield welding leaves slag on top of the finished weld. Let the weld cool before using a chipping hammer and a wire brush to remove the slag. After the slag is cleared, inspect the weld bead for consistency, porosity, and any signs of defects. A clean weld with good penetration and a smooth, even bead profile is what you should achieve.
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What Materials Can You Weld with Dual Shield Welding?
Carbon Steel
Dual shield welding works best on carbon steel. It delivers deep penetration and high-quality welds in mild and medium-carbon steels. It's the most common application of dual-shield welding in structural fabrication and construction.
Low-Alloy Steel
You can work with low-alloy steel using dual-shield welding, as long as you use the right dual-shield wire for the specific alloy. Low-alloy steels used in heavy equipment, pressure vessels, and structural applications benefit from the deep penetration and mechanical strength dual shield welding delivers.
Stainless Steel
Dual-shield welding can also be applied to stainless steel, but only with a proper combination of a flux-cored electrode and a shielding gas. It requires more careful control of parameters than carbon steel to avoid heat distortion and maintain the corrosion resistance of the base metal.
Safety Precautions for Dual Shield Welding
- Always wear proper PPE. Always wear proper PPE. The dual-shield welding arc is intense, and exposure can cause severe eye injury. Wearing appropriate welding helmets and auto-darkening welding lenses is important.
- Ensure adequate ventilation in your workspace. Dual-shield welding generates more fumes than solid-wire processes. Always work in well-ventilated spaces and use local exhaust ventilation or respiratory PPE when you're working in confined spaces.
- Examine your shielding gas connections before every session. Leaks in the gas supply not only affect the quality of your welds but also pose potential dangers in confined areas. Inspect all connections and hoses before striking the arc.
- Handle flux-cored wire correctly. Ensure that the dual-shield wire is dry and properly stored. Any moisture in the flux core results in porosity in the weld and may cause arc instability.
- Wait for the weld to cool down before removing slag. Trying to remove slag from a weld that hasn't fully cooled increases the risk of burns and can send hot slag flying.
- Keep your work area clear. Dual shield welding generates spatter. Ensure there are no flammable materials in your work area and that a fire extinguisher is within reach.
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Frequently Asked Questions
How Is Dual Shield Different From Flux Core Welding?
Flux core welding is a general term that encompasses self-shielded and gas-shielded processes. Dual-shield welding is the gas-shielded version that uses a flux-cored wire and an external shielding gas. On the other hand, self-shielded flux-cored welding uses only the flux-cored electrode, without any external shielding gas.
What Shielding Gas Is Used in Dual Shield Welding?
The shielding gas used in dual shield welding is often carbon dioxide or a blend of carbon dioxide and argon. The gas mix you use depends on the dual-shield wire and the base metal. Always check the wire manufacturer's recommendations for the correct shielding gas and flow rate before you start welding.
Is Dual Shield Welding Good for Beginners?
Dual shield welding has a steeper learning curve than basic MIG welding. However, it's manageable for beginners willing to understand the setup and parameters. Getting wire speed, shielding gas flow, and travel speed right is key to developing early, and carbon steel is always a good starting point.
What Thickness of Metal Can Dual Shield Welding Handle?
Dual shield welding is most appropriate for thicker base materials. This is due to its high heat input and deep penetration. It's less suitable for thin sheet metal, where burn-through can easily occur.
Conclusion
Dual Shield welding is a weld where it matters most. It offers high deposition rates, deep penetration, and strong welds for the materials that demand them most. Learning dual shield welding does take a bit of time. You'll need to have everything set up properly, make sure you're using the correct parameters, and practice on carbon steel until the process feels consistent.
As always, the proper personal protective equipment is essential. Make sure you're running every session with a proper welding hood and lenses that meet the demands of flux-cored arc welding.