There's a lot of fun fare and talk on welding aluminum using FCAW, with even wires promising FCAW for aluminum. But does it work? The answer is no, you can't weld aluminum with flux-core welding.
Table of Contents
Key Takeaways
- Flux-core Aluminum welding is not possible.
- Tests to validate the commercialization of flux core aluminum failed because it's unusable in the outside world.
- Alternative flux chemicals are corrosive to the weld joint.
- It's impossible to run the aluminum rod through a spool gun wire feeder; the only way to weld it is through soldering iron and brazing.
A steel-based flux core welding wire in your FCAW welder aimed at welding aluminum won't produce the expected joint because even the best flux core welder doesn't work with aluminum. Join in, and let's see if you can weld aluminum with flux-core welding. (Spoiler: nope, you can't!)
Can You Weld Aluminum With Flux Core?
The answer is simply no. It's not worth a trial for one; you will burn a welder because it requires more amps than the typical 130 Amp generates. I recommend that you get a combo welder like Miller Multimatic 220 to weld aluminum as well as other metals.
Plus, it produces a lot of splatters that clog the contact tip and short out the welder. That leads to a poor weld quality weld or an entirely failed one. So there's no point in doing it.
The only way to weld aluminum in the simplest ways is by aluminum soldering and brazing. You'll see this process in a few. But first, let's explore the truth behind the absence of an aluminum flux core wire and aluminum FCAW.
The Truth Behind the Absence of Aluminum Flux Core
The truth behind aluminum flux core wire is that it's solid and comes with a manufacturer's description that recommends using Argon gas.
That's a red flag because it shows you need a MIG welder, not an FCAW one. How do we know? A MIG welder uses shielding gas, meaning the rod is for MIG welding and not for Gasless flux core aluminum welding.
Again, the supposed "Aluminum flux core welding wires" are rods that have nothing to do with aluminum FCAW or even MIG welding. It's a solid aluminum wire used in soldering aluminum.
Also, the aluminum wire could be for the brazing machine. These machines run automatic wire feed used for the brazing process. The process has a tight air supply controlled using two ceramic tiles. So the wire rod is used in induction brazing which joints your weld.
You could be in an urgent tight situation, and you "think" you need that aluminum flux core welding wire, as the google results illustrate. It's not for flux core welding but aluminum welding, usually called aluminum soldering.
There’s No Flux or Flux Cored Aluminum Welding (FCAW) Wire
AWS (American Welding Society) had not given any standard FCAW by October 2022. Double-check if things changed through that link. It's improbable.
Also, flux chemicals, commonly used in MIG steel welding, don't work while welding aluminum. Why?
Because aluminum is hyper-reactive with air, that necessitates finding other newer shielding chemics. As yet, none is commercialized.
Failed Tests for Flux Core Wires for Aluminum: Not Working
Lab tests of aluminum fluxes promising to work for its flux core welder failed to commercialize. Though they worked in the laboratory, that's as far as they went.
The Reasons Why FCAW-Aluminum Wires Won’t Work
FCAW (flux core aluminum wire) won't work in the outside world as there's much control required. A gasless flux core welder will find that challenging.
Plus, it's hard to form a good shield in the electrical arc while welding because of its hyperactivity. The fact that that's impossible leaves the weld open to atmospheric contaminants and resulting in defective welds.
Second, the other alternative shielding chemicals used in the lab were corrosive. All welders agree that no one wants that for their weld.
Not only that, they absorbed atmospheric humidity as they were highly hygroscopic. That would cause you to have high storage specifications. Otherwise, your weld joint will be porous, poor, and fail in the long run.
Lastly, the flux-cored aluminum wire would cause an environmental hazard. The wire's shielding chemicals worked during testing but proved disastrous in the open environment.
What’s the Alternative for Aluminum Flux Core Welding?
I'm sure you know what flux core welding is and how to flux core weld other materials. That aside, the only alternative for aluminum welding is aluminum soldering. It requires a propane gas torch, a source of enough heat for the process. Then, a new brass wire brush you've not used on anything else. It's for cleaning off the oxidation on your aluminum rod. Any oxidation will cause the shoulder not to stick.
Remember your protective gear and two ceramic tiles to concentrate the heat on the weld joint as the vise holds the welding project together.
And finally, a pair of locking needle nose pliers for holding the aluminum rod, then the solid aluminum rod for soldering.
Tip: This process doesn't need any gasses.
The Process of Aluminum Welding by Soldering
There's a slight difference between flame torch joint soldering and brazing. Brazing uses brazing machines that provide the grazing fire to heat the aluminum base metal without melting it.
The solder material (aluminum) melts into a weld puddle that flows into the aluminum weld joint. The solder melts at lower temperatures than the brazing fire in soldering due to a lower heat.
Brazing Aluminum Welding; the Supposed “Flux-Core” Aluminum Process
The aluminum solder for brazing melts in higher temperatures of about 730 degrees Fahrenheit into the weld joint. The high temperature doesn't necessarily create a weld pool as in arc welding because this wire doesn't use an electrical arc like in FC arc welding.
You want a gas-flame welding torch for brazing, not the Metal Inert Gas Torch.
- Clean the joining to remove any oxidation using the wire brush or sandpaper.
- Bring the joints together, leaving a small gap of about 0.024 inches to get a sufficient flow of solder and sufficient strength.
- Heat the joint. The goal is to have it at 730 degrees which is hot enough to melt the solder and not so much so that the aluminum base metal doesn't melt. And voila! You're done.
That's how simple welding aluminum gets. Only ensure you don't hasten the cooling process by dipping in water because it produces a weak aluminum joint.
Frequently Asked Questions
Is There a Flux Core Wire for Aluminum?
No, there is no flux core wire for welding aluminum. Aluminum welding is done in one way only; soldering.
Can You Weld Aluminum to Steel With a Flux Core?
No, you can't weld aluminum to steel with a flux core. It will wreck your spool gun by producing many splatters that clog the tip.
What Metals Can You Weld With Flux Core?
You can weld the following metals with flux core welding.
- Mild steel
- Low-alloy steel
- Nickel
- Nickel alloys
- Stainless steel.
Can I Weld Aluminum With a Gasless MIG?
You can weld aluminum with a vacuum cylinder. The cylinder should be air-cooled. But when typically done, this technique exposes aluminum to atmospheric contaminants around your workspace, resulting in weaker joints.