[GLR444]

I am back with more aluminum welding questions, but this time MIG welding aluminum. When MIG welding 1/8” aluminum I am getting a lot of black residue (carbon?). The weld bead looks nice and shiny and is surround by line of oxide, but around that is about 1/4" of black residue. The residue is easily wiped off with a paper towel.

[Mark Petrov]

My first thought was contaminated Argon, but we attached the spoolgun to the tank we use for TIGing and we got the same results. I used that same tank to do a couple of beads with the Dynasty and things seemed fine (shiny bead, good cleaning, no mysterious residue). So, I am starting to doubt that it is the Argon. [links]

[ashleywittky]

Being new to welding, this may be entirely normal, however, when we first got the machine (MM252 w/ spoolmatic 30A) we tried MIGing some aluminum using our TIG argon and there was not nearly as much residue. We originally used the recommended setting of 19V which seemed to be enough for spray transfer to occur. Now, we needed to increase the voltage to 20.5V for spray transfer to occur. The only difference that I can think of is that we just received new argon.

[jago25_98]

You can’t do much about aluminum oxidation, and unless appearance matters, it’s not a big problem. Aluminum corrosion could however be a serious issue. If there’s any possibility of it happening you have two options: here

[Artlav]

Scratching this oxide skin exposes bare metal, and the process begins again. It won’t eat the metal away though, except under two conditions. First, if chlorides or sulfides are around they’ll attack the aluminum oxide layer. more

[jwalck]

Most metals want to corrode back to some form of ore. (Gold is one notable exception.) Corrosion starts with oxidation, where atoms of metal link up with oxygen, followed by a gradual, or not so gradual, breakdown. Rusting is a specialized form of corrosion that only iron and steel go through.

[sethsethseth]

Sorry Mister Stark, but iron is a lousy choice for a suit. It’s heavy, which will limit your ability to fly, and worse than that, it rusts. Spend too long in damp environments and you’ll find reddish brown flakes lifting off the surface. Aluminum would be better because its much lighter and doesn’t rust. Aluminum does corrode though, especially if exposed to seawater. Here’s an explanation, along with some tips on what to do about it.

[seq2010]

Chlorides are compounds of chlorine. Sodium chloride would be an example, which is the chemical name for salt. And where do you find lots of salt? In the ocean. Likewise, sulfides are sulfur compounds. They’re prevalent in areas of polluted air.

[DGCmagazine]

Again, 4043 is less crack-sensitive than 5356 and shows less tendency for crater cracking. If your component will be heat-treated after welding, use 4043; 5356 can be made susceptible to stress corrosion cracking after heat treatment. Similarly, if the component will operate at temperatures above 150 degrees F, use 4043 to avoid stress corrosion cracking.

[moncler321]

Q: Which filler wire is best for welding 6061-T6 aluminum, 5356 or 4043?

[traindirector]

An aluminum alloy containing 5 percent magnesium, 5356 generally is stronger and more ductile than 4043. But 4043, which contains 5 percent silicon, typically flows better, is more crack-resistant, easier to weld with, less prone to weld smut, and yields a more aesthetic weld.

[leonas7n3417]

You're probably wondering this: If 5356 is stronger, shouldn't I always use it? The answer is no. While 5356 is stronger than 4043, they're both stronger than the weakest area of the heat-affected zone (HAZ) in 6061-T6 butt welds. These butt welds fail in the HAZ—not in the weld metal—and the strength doesn't change, regardless of the filler metal. more

[mhatta]

A: Both are acceptable for welding 6061-T6, but each has advantages and disadvantages depending on the application. more

[granerica]

This isn't the same with lap or fillet welds. These welds almost always are stressed in shear loading in real-world designs, not in tensile loading like butt welds. Lap and fillet welds usually fail in the weld metal, and 5356 has a shear strength almost 50 percent higher than 4043. [links]