Advantages of Cored Wire in Submerged Arc Welding Applications | MillerWelds

Advantages of Cored Wire in Submerged Arc Welding Applications

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Understanding the important roles of the flux and wires can help companies realize the full potential of the submerged arc welding (SAW) process.

Full potential of the SAW process

Productivity is important in many manufacturing and industrial welding applications. But maximizing throughput without sacrificing quality requires careful selection of process, procedures, equipment and consumables.

Submerged arc welding (SAW) is a high-efficiency, high-productivity, wire-fed process. It's often used in demanding heavy industrial applications such as pressure vessel fabrication, offshore and wind tower production.

Solid wires are a familiar choice for SAW. But the productivity benefits of the process can be improved even more when paired with cored wire.

This article discusses the advantages that can be found by using cored wire in SAW applications.

Basics of cored wire

Cored wires are drawn from tubes filled with powder that is manufactured to introduce specific chemical or mechanical properties into the weld.

The primary advantage of this wire design is increased welding deposition rates. Cored wire can also be used to alloy the weld to compensate for high heat input and high dilution welds. In addition, the introduction of basic elements into the core composition can reduce oxygen content in the weld deposit to increase toughness.

The development and production of cored wires can be quite flexible and responsive. This helps meet evolving industry trends and application requirements, offering flexibility in some applications.

Greater deposition rates

Cored wires are, for many applications, a higher productivity alternative due to their greater deposition rates.

Cored wire requires greater wire feed speed to achieve a given amperage compared to a solid wire of the same diameter and welding contact-tip-to-work distance. This is due to the increased current density and resistive heating effect of cored wire. The energy of the arc is generally concentrated to the wire's solid outer “sheath” as opposed to the powdered core.

Increased deposition rates provide the ability to put more metal down in the same time compared to solid wires. This can be done without significantly changing amperage and voltage.

When deposition rates increase, it's often possible to use higher travel speeds than solid wires and still maintain a given weld size. This presents an opportunity to improve productivity by speeding up the process and reducing the time to complete a weld.

Labor is the largest cost of any welding operation. Even small reductions in cycle time can provide huge cost savings in the long run — without sacrificing weld quality.

Less part rework

The advantages offered by cored wires can also result in less part rework for an operation. This in turn helps improve productivity, save time and reduce costs.

Cored wires have a wider, shallower penetration profile compared to solid wire when welding using comparable procedures. This provides numerous advantages, including a minimized risk of burn-through and the potential for more cosmetically appealing welds.

A minimized risk of burn-through means there are situations where metal-cored SAW wire could eliminate the need for MIG welding a root pass. Or, passes could be performed on less-than-optimal conditions (e.g., relatively thin materials, poor fit-up, etc.) while still using high-current (productive) welding parameters.

Cored wire offers the potential for producing more cosmetically appealing welds, as well. It's often possible to more easily obtain flatter bead contours with smoother transitions at weld toe lines than with solid wires.

Increasing the travel speed without changing amperage reduces heat input. This may minimize weldment distortion and reduce or eliminate the need for costly, time-consuming straightening operations. The reduced heat input allowed by cored wires can also help reduce weld residual stress, and in some instances, improve mechanical properties.

Limitations and additional considerations

There are some considerations when deciding if cored wire is best suited for a specific SAW application.

The broader penetration profile of a cored wire helps minimize the risk of burn-through, but provides less penetration. Consider using solid wires where penetration must be very deep, such as square or narrow-groove welding on very thick materials. In these situations, the shallower penetration of cored wire may hinder consistently achieving complete fusion.

One alternative for some narrow joints is providing the best of both worlds with a tandem configuration that uses both solid and cored wires. Tandem Arc welding utilizes two torches to feed two wires into the same weld puddle. It allows use of a solid wire lead on DCEP polarity for maximum penetration, and a metal-cored trail on square-wave AC polarity to maximize deposition rates (a very popular configuration for tandem welding). Other configurations can also be used based on the application. Some advanced applications can have up to five torches feeding a single weld puddle to achieve very high travel speed.

Cored SAW wires are not as stiff as solid wires and are easier to deform. It's important to select the proper drive roll type and tension settings for optimal feedability and consumable life.

For seamed cored wires, V-knurled drive rolls should be used. For copper-coated seamless cored wires, U-groove drive rolls are a suggested option. Ideally, wire straightener and drive roll tension should be set as low as possible to straighten and feed the wire smoothly without allowing wire slippage. With any cored product, setting proper tension is critical.

Because cored wire is not as stiff as solid wire, it may be difficult to feed through long distances, sharp angles and some semi-automatic torches.

The potential to maximize results

Understanding the SAW process and the important roles of flux and wire consumables can help operations realize its full potential.

The numerous advantages SAW offers for productivity and weld quality — especially when paired with cored wire formulated for the process — make the investment one to consider in many heavy industrial applications.