Aluminum MIG Welding Wire

Aluminum MIG welding wire is used for welding aluminum parts where clean weld appearance, corrosion resistance, and reliable performance are required. Designed for use with MIG welders and wire feed systems, aluminum MIG wire supports consistent arc control and smooth wire feed across a range of fabrication and repair applications.

Common aluminum MIG wire alloys include 4043 and 5356, each suited for different materials and strength requirements. WeldingMart carries aluminum MIG wire in multiple diameters and spool sizes from trusted manufacturers, giving fabricators dependable options for shop work, trailer repair, and production welding.

Aluminum MIG Wire — ER4043, ER5356 & More

The right aluminum mig wire makes every joint cleaner and stronger. WeldingMart stocks ER4043, ER5356, and ER4047 in every common diameter and coil weight, shipped same day from Appleton, WI on orders placed before 3 PM CT. Free freight at $99 and up.

Top Aluminum MIG Welding Wire Alloys

ER4043 — Popular Choice for General Fabrication

ER4043 is the popular choice for 6000-series base metals. Its silicon additives content (4.5–6%) gives the weld pool excellent flow, cuts porosity, and resists hot tearing on joints sensitive to heat stress. It produces a bright weld finish — a bright weld finish makes inspection easy and reduces post-run cleanup. This alloy is used to weld 6061-T6, 6063, and similar base metals on automotive, HVAC, and structural projects.

Available as er4043 035 (.035 inch) and in .030 and 3/64 diameters. Stocked in 1 lb coils up to 16 lb rolls. A small 1 lb coil suits occasional users; the 16 lb roll cuts cost per pound for high-volume MIG GMAW runs.

ER5356 — High-Strength for Marine and Structural Jobs

ER5356 delivers about 5% magnesium for tensile strength around 38,000 PSI as-deposited — significantly above ER4043. Marine builders and structural fabricators prefer this aluminum mig wire when joints carry real load or face saltwater exposure. ER5356 also anodizes to closely match the base material, making it the right call when appearance after anodizing matters. Stocked in .030, .035, and 3/64; in small and 16 lb coil options for any MIG GMAW setup.

ER4047 — Lowest Hot-Tearing Risk, Maximum Flow

ER4047 carries roughly 12% silicon, giving the weld pool maximum fluidity and nearly zero cracking risk on dissimilar joints. It yields a clean, polished finish ideal for visible or decorative work. Stocked in 1 lb and 16 lb coils; ships same day.

How to Choose: Alloy, Diameter & Coil Size

Match the Filler to Your Base Metal

These alloys come in various grades. The right mig welding wire depends on which base metal series you're joining:

6061, 6063 (6000-series): ER4043 or ER4047 resist hot tearing and flow well. ER4043 .035 is the standard first item to stock for 6000-series work.
5052, 5083, 5086 (5000-series): ER5356 for corrosion resistance and higher strength in marine and structural applications.
3003, 1100 (1000/3000-series): ER1100 or ER4043 for soft, commercially pure base metals.
Cast alloys: ER4043 or ER4047; silicon content matches casting chemistry.

Diameter for MIG GMAW

For MIG GMAW on this material, diameter controls heat input more critically than with steel. Run .030 for thin-gauge sheet (14 gauge and lighter), .035 for the widest range of material thicknesses, and 3/64 for heavy plate and high-deposition runs. The er4043 035 size is our top-selling item in this category on any MIG GMAW rig.

Spool Sizes: x 1 lb Through Larger Coils

Choose a 1 lb coil when you switch alloys often or run occasional jobs on this material. The small-coil size fits most standard MIG GMAW guns and spool guns without adapters. Step up to a 16 lb coil for production runs to cut cost per pound. Each alloy in this collection is listed with x 1-pound and larger coil options — choose x 1-pound for occasional use. Use U-groove drive rolls and a Teflon liner in the gun to keep the filler feeding smoothly.

Shielding Gas Requirements

MIG GMAW on this material requires 100% argon shielding gas. CO2 blends cause porosity and destabilize the arc on this material. Run 20–25 CFH at the gun. For plate over 1/2 inch, adding helium to the argon increases penetration, but pure argon covers most situations. Check all gas line connections before production runs to avoid contamination of the joint.

Key Specifications

AWS Classification: ER4043, ER5356, ER4047, ER1100 — all rated for MIG GMAW and TIG processes per AWS A5.10.
Diameter: .030, .035, or 3/64 inch. Match your contact tip exactly; dedicated tips run one size up for easier feeding on soft wire.
Coil weight: Standard small coils through 16 lb production rolls. Larger coils = lower cost per pound.
As-deposited strength: ER4043 ~27,000 PSI; ER5356 ~38,000 PSI.
Packaging: Moisture-sealed where available. Aluminum welding wire is sensitive to humidity — absorbed hydrogen yields porosity during the run.

Common Uses for Aluminum MIG Wire

ER4043 and ER5356 handle a broad range of fabrication applications: automotive bumpers, marine hulls, HVAC ductwork, architectural extrusions, trailer frames, and hobby projects. ER4043 suits most automotive and HVAC jobs; ER5356 covers marine and structural situations where load-bearing strength and corrosion resistance are the priority. Each option ships same day from our Appleton, WI stock.

Why Buy from WeldingMart?

WeldingMart carries Lincoln Electric, Hobart, ESAB, and Forney in our Appleton, WI warehouse — not drop-shipped. Every order ships same day before 3 PM CT. Free freight on $99-plus orders. No order minimums. Our staff can help you match filler to machine, alloy to base metal, and coil size to your run volume.

Frequently Asked Questions

What is the difference between ER4043 and ER5356?

ER4043 uses silicon additives for fluidity and hot-tearing resistance on 6000-series base metals. ER5356 uses magnesium for higher as-deposited strength (~38,000 PSI) and better corrosion resistance in saltwater. ER4043 anodizes gray; ER5356 matches the parent metal more closely after anodizing. Choose based on base metal series and end-use environment.

Do I need a spool gun for aluminum MIG GMAW?

A spool gun is recommended for most setups. Experienced welders recommend a spool gun for aluminum mig wire because the soft wire birdnests in long push-only feeder runs. For gun lengths under 10 feet with .035 wire, a push feeder with a Teflon liner and U-groove drive rolls can work. For extended MIG GMAW runs over 12 feet, a spool gun or push-pull system is the better option.

What gas do I need for aluminum mig welding wire?

Use 100% argon for all MIG GMAW on aluminum. Never use CO2 blends — they destroy arc stability and produce severe porosity. Pure argon at 20–25 CFH is correct for virtually all mig welding wire jobs on this material. Check gas line connections for leaks before every production run.

How do I prevent porosity in MIG joints on aluminum?

Clean the base metal with a dedicated stainless brush, then wipe with acetone. Store wire sealed between sessions — this alloy is prone to humidity absorption and picks up hydrogen that causes porosity during the run. Set gas flow to 20–25 CFH. Use fresh, sealed filler; contaminated wire is a leading cause of porosity regardless of machine settings.

What does ER4043 .035 work best on?

ER4043 .035 (er4043 035) is used to weld 6061-T6, 6063, and other 6000-series alloys from 1/8 to 3/8 inch thick. It produces a clean, consistent finish, feeds reliably through most spool guns, and suits MIG GMAW machines from 130A up. A 1 lb coil is the right first purchase when qualifying this process in your shop.

What coil size should I order?

Buy a 1 lb coil for occasional use or alloy switching — the small-coil size fits most standard guns. Buy a 16 lb coil for production runs. Both deliver the same wire quality: identical chemistry, same mechanical properties, different package weight. The small-coil option is listed alongside larger sizes for every alloy in this collection.

Can aluminum mig wire be used for TIG?

Yes. ER4043, ER5356, and ER4047 are dual-classified for MIG GMAW and TIG. Cut the wire from the coil and use it as TIG filler. Most manual TIG runs use 3/32-inch rod; the chemistry is identical to the MIG GMAW wire regardless of process.

How do I keep aluminum mig wire clean during storage?

Store sealed in original packaging in a low-humidity area. Reseal any open coil in a zip-lock bag. This filler readily absorbs atmospheric moisture; the resulting hydrogen causes porosity during the run. A wire storage oven at 100–150°F helps in humid shops. Discard wire with visible pitting or surface oxidation — it will not deliver clean results.