MIG Welding Wire

MIG Welding Wire for Every Job — Shop WeldingMart's Full Selection

Whether you're running production passes on structural steel or patching a trailer hitch in the driveway, choosing the right wire is the foundation of a quality weld. WeldingMart carries over 220 wire SKUs from Lincoln Electric, ESAB, Hobart, Forney, and other brands that working welders trust. Orders placed before 3 PM Central Time ship the same day from Appleton, WI, and free freight kicks in at $99. Browse the collection, add to your cart, and get back to work.

Types of Welding Wire: Solid vs. Flux Cored

Two fundamentally different wire types dominate the MIG market: solid wire and tubular FCAW wire. Understanding which one fits your application is the first and most important decision you'll make.

Solid Wire (GMAW)

Solid wire is a single-metal electrode that relies on external cover gas to protect the molten weld pool from atmospheric contamination. It produces clean, low-spatter beads in controlled shop environments and is the go-to choice for automotive, light fabrication, and general manufacturing. The most common classification — ER70S-6 — runs on 75/25 Argon/CO₂ or straight CO₂ gas and handles light rust and mill scale better than older ER70S-3 formulations.

Flux Cored Wire (FCAW)

This tubular wire has a hollow center packed with flux compounds that generate a protective slag layer as you weld. There are two sub-types:

• Self-shielded (FCAW-S): No external gas required. Ideal for outdoor, field, and structural work where wind would blow away gas coverage. Common classifications include E71T-11 and E71T-GS. Runs DCEN polarity on most classifications.
• Gas-shielded (FCAW-G): Uses both internal flux and an Argon/CO₂ or straight CO₂ gas blend to achieve very high deposition rates and excellent mechanical properties. Preferred in shipbuilding, heavy fabrication, and pressure vessel work. Runs DCEP polarity.

FCAW wire generally handles thicker material faster than solid wire and tolerates surface contamination better. The trade-off is slag removal and higher cost per pound.

How to Choose the Right MIG Wire

Run through these five decisions before you drop anything in your cart:

1. Match Wire Alloy to Base Metal

Carbon and low-alloy steel: ER70S-6 solid or E71T-1 FCAW wire. Stainless: ER308L, ER309L, or ER316L. Aluminum: ER4043 or ER5356. Chrome-moly: ER80S-D2 or matched low-hydrogen FCAW consumable. Using the wrong alloy is the fastest path to a weld that looks fine but fails under load.

2. Select Wire Diameter for Your Machine and Metal Thickness

Wire diameter needs to match your machine's amperage range and the thickness of the base metal:

• 0.023" / 0.6mm: Sheet metal, 24–16 gauge, low-amperage hobby machines
• 0.030" / 0.8mm: Light gauge to 3/16", most entry and mid-level machines
• 0.035" / 0.9mm: The most popular all-around size — covers 14 gauge to 1/2" on mid-range machines
• 0.045" / 1.2mm: Heavy plate, structural, and high-deposition production runs

3. Confirm Your Shielding Gas Setup

Solid MIG wire always requires external gas coverage. Self-shielded FCAW wire does not. Gas-shielded FCAW wire does. The most common gas blend for mild steel solid wire is 75% Argon / 25% CO₂ (C25), which provides a stable arc, good penetration, and low spatter. Straight CO₂ deepens penetration and costs less but increases spatter. Aluminum requires 100% Argon — CO₂ causes porosity in aluminum welds. Stainless typically runs on tri-mix (He/Ar/CO₂) or 98/2 Ar/CO₂.

4. Indoor Shop or Outdoor Field Work?

Wind is the enemy of any gas-shielded process. If you're welding outside or in a drafty bay, the gas coverage will disperse before it can protect the puddle. Self-shielded FCAW wire solves this completely — no cylinder, no regulator, no gas flow to be disrupted. In a controlled shop setting, solid wire with a proper gas setup gives you cleaner beads and easier cleanup.

5. Spool Size and Hub Compatibility

Check your welder's spool hub before adding wire to your cart. Most machines accept 4" and 8" plastic spools. Larger industrial feeders take 12" or 16" spools. Spool sizes range from 1 lb trial rolls up to 44 lb production spools — match the size to your volume so you're not breaking welds to reload.

Key Wire Specifications You Need to Understand

AWS Classification Breakdown

The AWS classification printed on every spool tells you the wire's mechanical properties and intended use. For solid mild steel wire, "ER70S-6" reads as: E = electrode, R = filler rod capable, 70 = 70,000 PSI tensile strength, S = solid, 6 = chemistry designation (high Si/Mn deoxidizers). For tubular FCAW wire, "E71T-1C" reads as: E = electrode, 7 = 70,000 PSI, 1 = all-position, T = tubular, 1 = usage designation, C = CO₂ gas coverage required.

Tensile and Yield Strength

Most structural work on carbon steel is satisfied by 70,000 PSI tensile — it meets AWS D1.1 structural code minimums. High-strength steels (A514, T-1, Hardox) require matched or slightly under-matched consumables. Over-matching on high-strength steel can cause heat-affected zone cracking. Always pull the wire's Certified Material Test Report (CMTR) when the application is code-governed.

Copper Coating

Most mild steel solid wire comes copper-coated to improve electrical conductivity at the contact tip, reduce tip erosion, and lubricate the wire as it travels through the liner. Uneven copper coating causes arc instability and contact tip pitting. This is one reason to buy name-brand wire from Lincoln Electric, ESAB, and Hobart rather than unverified offshore products — their QC on coating consistency is proven.

Cast and Helix

Cast describes the diameter of the coil the wire naturally wants to form when it leaves the spool. Helix is the tendency to spiral. Both must be tightly controlled to prevent the wire from riding off-center in the contact tip groove or bird-nesting at the drive rolls. Quality wire from established manufacturers is precision layer-wound for consistent cast and helix across the full spool.

Applications by Industry and Job Type

Automotive and Auto Body

Auto body panels run 18–24 gauge steel. Use 0.023" ER70S-6 with C25 in short-circuit transfer mode. Keep stick-out short, travel speed brisk, and heat input low to avoid burn-through and distortion on thin sheet.

Structural Steel Fabrication

Structural fabrication commonly uses 0.035" or 0.045" ER70S-6 for solid wire passes, or 0.045"–1/16" FCAW-G wire for high-deposition fillet and groove welds on heavier sections. Code work under AWS D1.1 requires pre-qualified procedures or a qualified WPS — confirm the wire's Charpy V-notch impact data before specifying it.

Pipe Welding

Root passes on pipe are often made with ER70S-2 (which has additional deoxidizers for cleaner roots) while fill and cap passes use ER70S-6 solid wire or FCAW-G wire depending on position and code requirements. All-position tubular wire classifications are preferred when welding out of position on pipe.

Maintenance and Repair

Repair welding frequently involves rusty, scale-covered, or unknown-composition base metal. ER70S-6 handles light contamination better than any standard solid wire. For severely corroded steel or unknown alloys, self-shielded FCAW wire formulated for maintenance and repair gives additional tolerance for base metal chemistry variability.

Sheet Metal and Light Fabrication

Sheet metal shops typically run 0.030" ER70S-6 in short-circuit or pulse transfer. Pulse MIG programs on compatible machines virtually eliminate spatter and give precise heat control. Add 10 lb or 25 lb spools to your cart for light fabrication — 44 lb production spools are unnecessarily heavy for low-volume sheet work.

Aluminum Fabrication

Aluminum wire requires a spool gun or push-pull system to prevent bird-nesting in standard steel liners. ER4043 is softer, flows easily, and works for most general aluminum applications. ER5356 is stronger and better suited to applications where the part will be anodized or needs higher weld strength. Run 100% Argon — no exceptions.

Brands Available at WeldingMart

We carry wire from manufacturers whose quality we've tested and whose technical support is real:

• Lincoln Electric: SuperArc® L-56 is one of the best-selling ER70S-6 solid wires in North America. Innershield® self-shielded wire for field and structural work has been the industry benchmark for decades. Lincoln's layer-wound spools feed consistently from first pass to last.
• ESAB: Dual Shield® FCAW-G wire covers a broad range of impact toughness grades for structural, offshore, and pressure vessel applications. Spoolarc® solid wire is a proven performer in high-volume production environments.
• Hobart: Fabshield® self-shielded wire and FabCO® gas-shielded wire are known for easy slag removal and reliable arc starts. Hobart solid wire delivers consistent chemistry at a competitive price point.
• Forney: Strong value-to-price ratio for hobbyists, farmers, and light fabricators. Forney wire runs clean on standard machine settings and is well-suited to general repair and fabrication.

Why Order from WeldingMart?

WeldingMart is based in Appleton, WI, and has supplied professional welders and industrial buyers for years. Here's what you get when you order from us:

• Same-day shipping on orders placed before 3 PM Central Time
• Free freight on $99+ orders — most wire orders hit this threshold easily
• 224+ wire SKUs in stock — solid wire, FCAW wire, stainless wire, and aluminum wire across all common diameters and package sizes
• Name brands only — Lincoln Electric, ESAB, Hobart, Forney, and other trusted manufacturers
• Expert support — call or email our team with wire selection, machine compatibility, or gas pairing questions and get a real answer from people who weld
• Easy reorder — add your go-to wire to your cart and check out in minutes; no hunting through multiple distributors or minimum order headaches

Preheat, Interpass Temperature, and Wire Selection for High-Strength Steel

Most welders working on structural mild steel never need to worry about preheat. But once you step up to higher-carbon or high-strength steel, preheat becomes critical — and wire selection plays into it directly.

Why Preheat Matters

Preheat raises the temperature of the base metal before welding begins. This slows the cooling rate of the heat-affected zone (HAZ), which reduces the risk of hydrogen-induced cracking (also called cold cracking or delayed cracking). For steels with a carbon equivalent (CE) above approximately 0.40, preheat is typically required. AWS D1.1 structural code tables give minimum preheat temperatures by steel group — know your base metal and look it up before welding.

Wire Hydrogen Content and Preheat Requirements

Lower-hydrogen wire classifications reduce preheat requirements for a given steel. ER70S-6 solid wire is inherently low-hydrogen (typically <5 mL/100g) when stored and handled correctly, which is one reason solid wire is preferred over SMAW electrodes in many structural shops — it requires less preheat for equivalent steel chemistry. FCAW-G wire classifications with H4 or H8 diffusible hydrogen designators are specified when the application requires documented low-hydrogen performance.

Interpass Temperature

On multi-pass welds, interpass temperature is the temperature of the previous bead when the next pass is started. Too hot and you can overheat the HAZ and soften the steel. Too cold and you lose the benefits of preheat. For most structural carbon steel work, interpass temperature is maintained between preheat minimum and 400°F–600°F maximum. Check your project's WPS for project-specific limits — these numbers vary by base metal specification and code requirements.

Comparing Transfer Modes: Short Circuit, Globular, Spray, and Pulse

The way metal transfers from wire to base metal affects spatter, penetration, bead profile, and out-of-position capability. Wire type, diameter, voltage, and current all interact to determine which transfer mode you're operating in.

Short Circuit Transfer

Short circuit is the lowest-energy transfer mode. The wire tip actually touches the base metal, creates a short, and the droplet transfers across. It's quiet, controllable, and ideal for thin material and out-of-position welding. It's the dominant mode for 0.023"–0.035" solid wire on hobby and light industrial machines. The downside is lower penetration and potential for cold lap on heavier material if travel speed or amperage is too low.

Globular Transfer

Globular transfer occurs between short circuit and spray. Large, irregular droplets form and fall across the arc — it produces more spatter than other modes and is generally avoided in precision fabrication. It's the unintended consequence of running at intermediate voltage and WFS settings on standard machines without pulse capability. Most experienced welders tune past globular into proper spray transfer when they need higher deposition.

Spray Transfer

Spray transfer produces a fine stream of small droplets across a stable arc. It's the highest deposition and deepest penetrating mode for solid wire, but it requires a high-Argon gas blend (typically 80% Ar or higher) and higher amperage (above the spray transition current for the given wire diameter). Spray transfer is flat or horizontal only — it can't be used out of position without a pulse program because the puddle is too fluid.

Pulse MIG

Pulse MIG cycles rapidly between a high peak current (for droplet detachment) and a low background current (for arc stability). The result is spray-like droplet transfer with significantly lower average heat input. This makes pulse ideal for thin material, aluminum, stainless, and any application where distortion or burn-through is a concern. Pulse programs are machine-specific and typically built around specific wire types and diameters — use the pulse program designed for the wire you're running for best results.

Wire Quick-Select Reference

Use this table before you add to your cart to confirm you're ordering the right product:

• Mild steel, clean, indoor shop: ER70S-6 + C25 Ar/CO₂ blend
• Mild steel, rusty/scaled, indoor: ER70S-6 + C25 or 100% CO₂
• Mild steel, outdoor or windy: Self-shielded E71T-11 or E71T-GS — no gas needed
• Heavy steel, high production, indoor: Gas-shielded E71T-1C/1M + CO₂ or C25
• Stainless: ER308L / ER309L / ER316L + tri-mix or 98/2 Ar/CO₂
• Aluminum: ER4043 or ER5356 + 100% Argon via spool gun
• Chrome-moly: ER80S-D2 or matched low-hydrogen FCAW wire + appropriate gas

Understanding Wire Feed Speed and Machine Settings

Wire selection and machine setup go hand in hand. The best wire on the market won't produce good results if your machine is mis-set. Here's a quick framework for dialing in your settings when you switch wire types or sizes.

Wire Feed Speed (WFS)

Wire feed speed is measured in inches per minute (IPM) and directly controls current when you're running a constant-voltage machine. Higher WFS equals more current and more heat. The relationship is approximately linear on most industrial machines. As a rough starting point for 0.035" ER70S-6: 200–250 IPM for thin gauge in short circuit, 300–400 IPM for heavier material in globular or spray transfer. Always check your machine's chart first and fine-tune from there.

Voltage Setting

Voltage controls arc length and bead profile. Too low and you get a high, narrow bead with poor fusion. Too high and the arc becomes unstable, spatter increases, and you get undercut on the toes of the weld. Most machines have a suggested voltage range printed next to the wire feed speed chart. A good starting point is 17–19V for short circuit on light material, 22–26V for spray transfer on plate.

Travel Speed

Travel speed — how fast you move the gun along the joint — affects deposition rate, bead width, and penetration. Slower travel deposits more metal and increases penetration; faster travel produces a narrower, thinner bead. For out-of-position welding, faster travel speed helps control puddle sag. For flat or horizontal groove welds on heavy sections, slower travel with weave or oscillation builds up the joint efficiently.

Contact Tip to Work Distance (CTWD)

Also called stick-out, CTWD is the distance from the end of the contact tip to the work surface. Longer stick-out (3/4" to 1") increases electrical resistance in the wire, which adds preheat and affects arc characteristics — useful for some high-deposition techniques. Shorter stick-out (3/8" to 1/2") gives better arc control and is standard for most short-circuit transfer and all-position welding. Keeping stick-out consistent is more important than the exact number — variation is what causes erratic arcs.

Drive Rolls, Liners, and Contact Tips: The System Behind the Wire

The wire itself is only part of the system. Drive rolls, liners, and contact tips all determine how consistently the wire feeds and how reliably the arc behaves. Here's what to know about each.

Drive Rolls

Drive rolls grip and push the wire from the feeder to the gun. Roll geometry matters: V-groove rolls are standard for solid wire. Knurled rolls are used for harder wires like stainless. U-groove rolls are designed for soft aluminum wire to prevent deformation. Using the wrong roll type can shave wire, create metal debris that contaminates the liner, and cause feeding problems. Most machines come with reversible or interchangeable rolls — check what's installed before you load a new wire type.

Wire Liners

The liner runs from the feeder through the cable to the contact tip. For mild steel and stainless wire, a steel coil liner is standard. For aluminum wire, a Teflon or nylon liner is required — aluminum is soft enough that steel liners shave particles off the wire surface, causing liner plugging and inconsistent feeding. Liners should be replaced whenever you notice feeding resistance, erratic arc, or visible debris at the contact tip. A worn liner is one of the most common causes of unexplained feeding problems and is often overlooked during troubleshooting.

Contact Tips

The contact tip transfers current from the cable to the wire at the point of electrical contact. Contact tip bore diameter must match wire diameter — a 0.035" bore for 0.035" wire. Tips that are too tight will seize; tips too loose will arc inside the tip, causing burnback and premature tip failure. Replace contact tips at the first sign of elongation or spatter buildup. We stock contact tips from Tweco, Tregaskiss, Bernard, and other leading manufacturers alongside our wire selection.

Wire Packaging Options Explained

Wire comes in several packaging formats beyond the standard plastic spool. Knowing the options helps you order the right package for your production volume and machine setup.

Standard Spools (4", 8", 12")

Standard plastic spools in 4" (1–2 lb), 8" (10–25 lb), and 12" (33 lb) sizes fit most wire feeders directly. The spool hub on your machine must match the spool hub diameter. Most hobby and mid-range industrial machines run 8" spools. 4" mini-spools are ideal for spool guns or trial quantities when switching wire types or testing a new classification before committing to a larger spool.

Drums and Payoff Packs

High-volume production operations often use 500 lb or 1,000 lb wire drums (also called payoff packs or marathon packs). The wire is precision coiled in the drum and feeds from the bottom-up through a straightener to the feeder. Drum packaging dramatically reduces spool change-out time in continuous production environments and lowers per-pound wire cost. Not all wire is available in drum form — contact us if you need bulk drum quantities for production runs.

Retail Rolls and Trial Spools

1 lb and 2 lb retail spools let you try a new wire type or diameter before committing to a larger quantity. If you're evaluating a new classification for a specific application, start with a small spool before stocking 10+ lb. We carry retail rolls in the most popular diameters of solid wire so you can test before buying in bulk.

Welding Wire Storage and Shelf Life Best Practices

Wire storage is often an afterthought until a spool shows up at the job site with a rust film or the welds start showing porosity. Here are the storage best practices that prevent rejected welds and wasted material.

Temperature and Humidity Control

Store wire indoors at stable room temperature — ideally 65–85°F with relative humidity below 60%. Wire stored in an unheated building in a humid climate will accumulate surface moisture, especially overnight when temperatures drop. Even a thin moisture film on solid wire can introduce hydrogen into the weld deposit and cause porosity.

Original Packaging Until Use

Keep wire in its original sealed plastic wrap until you're ready to spool it. The packaging acts as a moisture barrier. Once opened, reseal with plastic wrap or store in a heated storage cabinet if the wire won't be used within a few days in humid conditions.

Shelf Life

Most manufacturers recommend using wire within 12–24 months of manufacture. Properly stored solid wire can last longer without degradation. FCAW wire is more moisture-sensitive — the flux in the core can absorb hydrogen, which is why opened spools should be used promptly or stored in low-humidity conditions. Always check the manufacture date on the spool label and rotate stock so older material gets used first.

Rusty Wire: Usable or Replace?

Light surface rust on solid wire — the kind you can wipe off with a clean rag — is generally acceptable for non-critical repair and fabrication work. Heavy rust that pits the surface or flakes off in the liner will cause liner contamination, feeding problems, and weld quality issues. When in doubt, replace the spool. Wire is relatively inexpensive; rework and rejected joints are not.

Frequently Asked Questions About MIG Welding Wire

What is the difference between ER70S-3 and ER70S-6?

ER70S-6 has higher silicon and manganese deoxidizer content than ER70S-3. This makes ER70S-6 more tolerant of rust, mill scale, and surface contamination. ER70S-3 is preferred for very clean base metal where minimal deoxidizer dilution is required. For most general fabrication, repair, and maintenance work, ER70S-6 is the right pick and is stocked in far more diameters and spool sizes.

Do I need shielding gas with flux cored wire?

It depends on the wire type. Self-shielded FCAW wire requires no external gas — the flux inside generates its own protective atmosphere. Gas-shielded FCAW wire requires CO₂ or an Argon/CO₂ blend. Running gas-shielded wire without proper gas coverage will produce porous, contaminated welds. Check the classification on the label: E71T-GS and E71T-11 are self-shielded; E71T-1C requires gas.

What shielding gas is best for ER70S-6?

75% Argon / 25% CO₂ (C25) is the standard recommendation. It balances arc stability, penetration, and spatter control well for most applications. Straight CO₂ deepens penetration and costs less but generates more spatter. Very high Argon blends (above 90%) can cause lack of fusion at higher travel speeds on mild steel.

How do I choose wire diameter?

Match wire diameter to your machine's amperage range and your base metal thickness. Use 0.023"–0.030" for thin gauge up to 3/16", 0.035" for most general fabrication up to 1/2", and 0.045" or larger for heavy plate and structural work. Most welders have a wire/amperage chart inside their machine's door panel — check it before changing diameter.

What wire works best on rusty or dirty metal?

ER70S-6 solid wire handles light rust and mill scale better than any other standard solid wire. For heavily contaminated or corroded steel, self-shielded FCAW wire (E71T-GS or E71T-11) provides even greater tolerance for base metal impurities. Always clean the weld zone as thoroughly as practical regardless of wire type.

Can I use any wire on any MIG welder?

As long as the wire diameter matches the machine's drive roll groove size and liner bore, yes. Changing wire diameter usually requires swapping drive rolls and contact tips. Aluminum wire requires a Teflon liner — standard steel liners shave soft aluminum wire and cause feeding problems. Check your machine's manual for compatible wire types.

What is flux cored wire used for?

Flux cored wire is used for welding thicker steel sections, outdoor and field work where gas coverage is easily disrupted by wind, high-deposition-rate production welding, structural and heavy fabrication, and all-position welding on code work. Self-shielded FCAW wire is standard in construction and heavy equipment repair. The gas-shielded process dominates shipbuilding, pressure vessel fabrication, and high-volume structural shops.

How should I store wire to prevent rust and moisture damage?

Store wire in a clean, dry location away from humidity. Keep the spool wrapped in its original plastic bag until use. Solid wire exposed to moisture can rust, causing feeding problems and porosity. FCAW wire is especially sensitive — moisture absorbed into the flux can cause hydrogen-induced cracking. Use wire within 12–24 months of manufacture and avoid storing wire in unheated buildings in humid climates.

Is there a minimum order?

No minimum order. You can add a single spool to your cart and check out. Spend $99 or more and free freight is automatically applied at checkout — many welders combine wire with contact tips, liners, or nozzles to hit the threshold in one order and eliminate shipping costs entirely.

Which brand of wire should I buy?

Lincoln Electric, ESAB, and Hobart are the top three brands for professional and industrial applications. Their chemistry consistency, precision layer winding, and technical support are proven at scale. Forney is an excellent choice for hobby, farm, and light fabrication use at a lower price point. All brands we stock have passed our quality review — you won't find mystery offshore wire in this collection.