# Welding aluminum



## jwmay (Jul 15, 2021)

I've often been told you can't weld steel to aluminum. Today I discovered evidence this is just untrue.


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## macardoso (Jul 15, 2021)

hmmmmm. I'm not a welder, but I wonder about galvanic corrosion with the now mixed metals? I'm also not sure what the "alloy" is that gets made in the weld puddle. If you got hot enough to melt the steel, you'll have some sort of aluminum-iron alloy in the puddle. If only the aluminum melted then I guess it is more of a braze.


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## jwmay (Jul 15, 2021)

No need to worry. It's been "re-engineered" to all steel.  I don't imagine it's been in service  for longer  than 13 hours. I watched a couple different guys try to break it though, and it held up.


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## Ulma Doctor (Jul 15, 2021)

aluminum and steel will not mix under normal conditions.
the aluminum and/or steel may have melted, but didn't likely form an alloy 
there is a process using explosives that will adhere dissimilar metals such as aluminum and steel
short of that, i think the bolts gave the assembly any kind of strength


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## Tim9 (Jul 22, 2021)

Ulma Doctor said it well. Sure, you can melt both metals and they will “puddle” together. But in the sense of the word “weld”… what you have is not a true weld. You’ve just melted both metals. Good luck having that stand up to abuse .


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## jwmay (Jul 23, 2021)

Tim9 said:


> Sure, you can melt both metals and they will “puddle” together. But in the sense of the word “weld”… what you have is not a true weld. You’ve just melted both metals. Good luck having that stand up to abuse .


I think you're playing a little fast and loose with the word "you". Haha
I didn't make that abomination. I just found some other yoohoos "repair", while trying figure out why the machine destroyed one of its sensors.  As for why it was done in the first place, I doubt we'll ever know. We are experiencing no shortage of suitable chunks of steel.  Sometimes a person finds an overly craptastic repair, and the reason ends up being that we just didn't have a better option at the moment it was needed. But this garbage was above and beyond wrt useability, design, execution, and durability. Just a fail on every level. But still...like I said...we tried to break it, and it wouldn't. That's how it ended up memorialized on the hallowed pages of the HM forum.


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## MrCrankyface (Jul 23, 2021)

I've sometimes used aluminium as backing when I've welded/filled gaps and just one of the materials melting into the pores of the other can create an incredibly strong bond. 
I imagine it's somewhat similar to how soldering works albeit obviously unpredictable and much weaker.


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## rwm (Jul 23, 2021)

That sure looks like someone tried to weld it. Do you think the filler is steel?
Robert


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## jwmay (Jul 23, 2021)

I think they picked up the first piece if junk they found at the welding table, and MIGed it. Nobody uses anything but the MIG. We only have one guy that "knows" how to run the multi process machine, and NOBODY is gonna use the torch for anything but heating up stuck stuff.


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## rwm (Jul 23, 2021)

I could see the MIG gun making holes/pits in the aluminum and filling them with steel. You might get a mechanical bond that way that would be hard to pull apart.
Robert


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## Tim9 (Jul 26, 2021)

rwm said:


> I could see the MIG gun making holes/pits in the aluminum and filling them with steel. You might get a mechanical bond that way that would be hard to pull apart.
> Robert


Yeah...might be hard to "pull apart".... But Id hate to be behind the boat trailer where the bozo used some aluminum pieces because he ran out of steel angle iron.

And JW...Im happy to hear that you were just commenting on some photos. FWIW...Im surely no expert. And welding technology is always advancing. So I guess I should never say never. That said, Ive always felt that aluminum and steel don't mix well. Not even when bolted for that matter since the galvanic nature of the corrosion.


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## whitmore (Jul 26, 2021)

If one DOES want to join aluminum and steel, there's that zinc-based aluminum
solder to consider; it flows at propane-torch temperatures, and works adequately
on very clean aluminum, as well as steel, and galvanized steel (without any
need to remove the galvanizing).   Not really a good structural weld, of course.


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## Tim9 (Jul 28, 2021)

I’ve never tried those muggy weld zinc based sticks but I’ve read quite a number of positive comments about them. And other companies now sell them so there’s probably a decent market for them. And if it didn’t work, I doubt that there would be a market for them.
On a side note, I ran across this the other day on YouTube. Jody on welding tips and tricks used aluminum arch welding sticks and dc Tig and it looks like it worked okay. Not pretty, but decent penetration. Really a neat trick. And FWIW, I’m pretty sure he’s using Argon gas…. Dc Tig…. And 3/32 aluminum arch welding sticks as the filler.
DC Tig aluminum and arch aluminum stick weld.


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