MIG Wire Selection Guide

MIG Wire Selection Guide

How to Choose the Right MIG Wire for a Good Weld Strength

Choosing the right type of MIG wire is critical for the look and strength of the welds you create. In some cases, it will depend on the kind of welding machine you’re using and in others, it will depend on the method. Whatever the case, you want to make the choice that allows for the best level of weldability. This includes:

  • Weld metal soundness
  • Weld puddle fluidity
  • Bead shape and edge wetting
  • Spatter tendency

Other factors to take into account include shielding gas and arc voltage. Both can have a significant impact on cost.

Weld Metal Soundness

Soundness in the weld metal is characterized by a lack of porosity, as well as good fusion and freedom from cracking. Porosity is the most common cause of poor weld soundness and is caused by excess oxygen from the atmosphere, the shielding gas, and any base plate surface contaminants combined with carbon in the weld metal. This forms bundles of carbon monoxide (CO) gas. Some of the CO can become trapped as the weld cools, forming pores.

Typically, the MIG wire process is recognized as having very low hydrogen in the deposit. Although, factors – such as moisture in the shielding gas, atmospheric conditions, and plate condition – may impact the actual diffusible hydrogen in the weld deposit.

To minimize CO formation and porosity, sufficient deoxidation of the weld puddle is needed. To accomplish this, Spoolarc MIG welding wires contain elements that combine with oxygen instead of carbon to form harmless slags.

These elements, called deoxidizers, are manganese (Mn), silicon (Si), titanium (Ti), aluminum (Al), and zirconium (Zr). Aluminum, titanium, and zirconium are very powerful deoxidizers — perhaps five times as effective as manganese and silicon.

Weld Puddle Fluidity, Bead Shape & Spatter

The fluidity of the molten weld puddle is also important to consider for several reasons. Fluid puddles tend to wet out smoothly at the edges and produce a flat, smooth bead shape, especially on fillet welds. This can impact multi-pass, short arc welds where lack-of-fusion defects can occur if bead shape is poor. Flat, well-wet-in beads are also desirable where appearance is a primary concern and where post-weld grinding may be necessary to meet job requirements.

(Caution: Excessive puddle fluidity can cause performance difficulties in out-of-position welding or in making concave horizontal fillets.)

Choosing the manganese and silicon content of a MIG wire is another major decision to take into account. Increasing manganese and silicon likewise affects puddle fluidity, bead shape, and other factors. The Al, Ti, and Zr deoxidizers in Spoolarc 65 wire tend to make its puddle somewhat sluggish. The “stiff” puddle characteristic makes this wire ideal for pipe – especially small diameter pipe – and many other out-of-position welding jobs.

Shielding Gas & Arc Voltage

Many welders don't fully understand the impact that shielding gas and arc voltage can have on the bottom-line cost of the welding operation. However, both are critically important to take into account for the following reasons:

  • CO2 shielding causes more turbulent wire-to-base plate metal transfer and tends to create a more crowned bead with greater spatter loss.
  • Argon-based shielding gases provide more stable, uniform wire-to-base plate metal transfer, well-shaped beads, minimal spatter loss, and a lower fume generation rate.
  • Increasing arc voltage tends to increase puddle fluidity, flatten the weld bead, increase edge wetting, and increase spatter. Higher voltages also reduce penetration and may cause additional loss of alloying elements.
  • Spoolarc wires are processed as copper-coated using the proprietary ESAB HI DEP III manufacturing process, or as a “bare” (uncoppered) product. Spoolarc wires are available in a variety of alloys, wire diameters, and packages to meet the most demanding customer applications.
  • Spoolarc wires, either copper-coated or “bare,” provide excellent feedability and arc stability under the roughest shop conditions and most demanding applications even at high wire feed speeds. This means less downtime and greater productivity.

(Note: Spoolarc “bare” wires are a standard product for customers requiring or preferring no copper coating.)

Why ESAB for MIG Wires

All Spoolarc MIG wires are cleaned after the final drawing process to remove residual drawing lubricants. They are then treated with a proprietary ESAB process to ensure the best results.

For instance, ESAB offers:

  • Better performance: Spoolarc HI DEP III (copper-coated) wire has a matte finish with a low (typically 0.05% wt.) copper coating that is thin and tightly adherent. This eliminates troublesome copper flaking that is common with conventional MIG wires that are “shiny” in appearance. These “shiny” wires are generally higher in copper coating levels (up to 0.30% wt.), which makes them more prone to flaking, impacting performance.
  • High tensile strength: ESAB also draws most MIG wires directly from the rod to the final size, resulting in a high tensile strength product. This leads to greater resistance to buckling under compression and stops “birdnesting” when restrictions in the feed system do occur.
  • Low splatter: In addition, while splatter is a common problem with other MIG wires, ESAB Spoolarc wires produce excellent spray arcs at lower voltages, providing precise control of the welding process. This offers lower weld metal hydrogen levels and better penetration.
  • Longer lifespan for contact tips: ESAB Spoolarc wires also increase the life of contact tips. In fact, ESAB’s proprietary manufacturing process results in better current transfer, less arcing, and reduced contact tip erosion, especially at high current and wire feed speeds. This means fewer worn-out contact tips and a sizable saving in replacement parts, labor, and downtime.
  • No hydrogen issues: Finally, with Spoolarc MIG wires, there’s no absorbent coating and no moisture pickup. This tight control of surface residuals produces a high-quality weld without common hydrogen problems. As a result, there’s no need for drying ovens to recondition electrodes that may have absorbed moisture.

Don’t Forget to Test The Weld

Most of the data in this guide are based on AWS tests performed under standard conditions. In normal practice, however, the results can differ. The following factors can affect the results produced by any wire/gas combination:

  • Base plate chemistry
  • Base plate metal thickness
  • Weld bead wire size
  • Dilution of the base plate with weld metal
  • Heat input (affects weld cooling rate)

It’s therefore important to test the selected wire/gas combination in the same joint and under the same condition that would be used during actual production.