Tig welding Magnesium Alloy

[ants2au]

Hi,

this may be a bit tricky, but does anyone know what type of filler rod is needed for Magnesium alloy rims? These are not alloy rims.
Alas, i don't know the magensium content of them, although I have heard same type as helicopter alloy (if anyone knows what that would be)

Any special needs for welding these? Like setting these things alight if they get too hot

Thanks, Anthony

[PaulG]

I have never welded Magnesium, but whether they are Aluminum or Magnesium, it's highly advisable not to be welding on them if they will be used on a vehicle. $.02

[Gene_Olson]

long ago I welded up a magnesium bell housing for a guy.
None of the local shops stocked Magnesium rod.

I finally found a job shop with some.
It welds fine under argon.

Watch your grinding and filings. Those tiny bits are quite flamable.

The book says
"Magnesium alloys may be welded to each other and to similar magnesium alloys "(corrosion and embrittlement problems)
"As is the case with aluminum, magnesium welds do not have the tensile strength of cold worked or heat treated material but the welds are stronger than the same alloy as-cast"

"In setups allow for expansion and contraction of the weld area, especially for the alloys over 1% zinc and 5% al as they are suseptible to cracking."

It also says that very low alloy magnesium can be gas welded but only butt welds are recommended.

Rims?
(I see Paul has the same concern)

G.

[TheRodDoc]

A tire jockey broke a piece, the lip, off of one of my magnesium American Dragster rims several years ago and I welded it with the tig and magnesium rod. It welded very easily to my surprise. Welded much the same as aluminum.

Still there today on my street rod.

[Bambi]

First you need to determine that it truly is magnesium and not an aluminum alloy, many of which have minute amounts of magnesium in them. You would be looking for instant failure if you welded a magnesium wheel with aluminum and vica versa an aluminum wheel with magnesium is also destined for failure.
I have my doubts as it being magnesium since very few companies that produced magnesium wheels and were highly priced items to boot.
Magnesium can be ground with proper wheels and machined, the big problem is chips and grinding dust containing magnesium, once on fire you can not put it out. Water would cause an explosion and highly toxic gases. Many machine shops won't work with it cuz if it catches fire on a machine, you lose the machine too. Many folks don't know that titanium can also catch fire.
Welding of magnesium can be done with Oxy Acetylene, Tig Mig etc. with OA you need a flux, results will be the same if you used Tig or mig. Prep as aluminum, clean the work area from all dust and chips.
AZ92 is the alloy rod that would be used for a mag casting.
Now don't go out and try this but if you had a piece of magnesium plate you could bring it up to melting point with a cutting torch and hit the Oxy to cut and you wouldn't start a fire, but get those chips or dust going and the plate will go too.
I still doubt that it is magnesium, plus todays magnesium castings have the word magnesium cast into them, old stuff is a crap shoot.
Now don't go out and burn the place down.
Bambi

[ants2au]

They are Cromodora rims (They are usually supplied on Fiat and Ferrari). these definitely have Mg content, just not sure of the %. and yeah they are old. One set are off a Fiat, and the other off a Dino. The Dino ones are a bit pitted (I think they were not prepared properly for painting and have corroded a bit)

So if they do have Mg content with Al, do you weld with Mg or Al filler?

Thanks for the concerns though, I will probably heed them and not attempt this.




First you need to determine that it truly is magnesium and not an aluminum alloy, many of which have minute amounts of magnesium in them. You would be looking for instant failure if you welded a magnesium wheel with aluminum and vica versa an aluminum wheel with magnesium is also destined for failure.
I have my doubts as it being magnesium since very few companies that produced magnesium wheels and were highly priced items to boot.
Magnesium can be ground with proper wheels and machined, the big problem is chips and grinding dust containing magnesium, once on fire you can not put it out. Water would cause an explosion and highly toxic gases. Many machine shops won't work with it cuz if it catches fire on a machine, you lose the machine too. Many folks don't know that titanium can also catch fire.
Welding of magnesium can be done with Oxy Acetylene, Tig Mig etc. with OA you need a flux, results will be the same if you used Tig or mig. Prep as aluminum, clean the work area from all dust and chips.
AZ92 is the alloy rod that would be used for a mag casting.
Now don't go out and try this but if you had a piece of magnesium plate you could bring it up to melting point with a cutting torch and hit the Oxy to cut and you wouldn't start a fire, but get those chips or dust going and the plate will go too.
I still doubt that it is magnesium, plus todays magnesium castings have the word magnesium cast into them, old stuff is a crap shoot.
Now don't go out and burn the place down.
Bambi

[PaulG]

Anthony,

I am familiar with Cromodora rims. Why don't you disclose what your intentions are? Are you welding because they are cracked, or because they are pitted?

Is this a structural issue, or a cosmetic one? If it's structural, then despite what you might hear on this forum or anywhere else, unless you are using these for "yard art", it is foolish to weld them regardless of the Mg content.

If however it's a pitting problem, then depending on the severity of the pitting, they may be saved, but welding is not the answer for pitting.

[ants2au]

Yep, just a pitting problem.

One of the rims (the Fiat one) about 15years ago, was damaged in a curb crash, (cracked the edge of the rim) and was fixed by a wheel place. I wasn't happy with the work done on it (they lathed it to a different profile), but have lived with it since (drove the car around all that time).

This question was really two fold. One - can something like this be attempted by a dope like me (for future reference), and two, the pitting problem.

Sure i can use putty on the pitting problem, but thought I would ask about welding them first.

I always new that welding these things is not for the backyard person, but thought I would ask.



Anthony,

I am familiar with Cromodora rims. Why don't you disclose what your intentions are? Are you welding because they are cracked, or because they are pitted?

Is this a structural issue, or a cosmetic one? If it's structural, then despite what you might hear on this forum or anywhere else, unless you are using these for "yard art", it is foolish to weld them regardless of the Mg content.

If however it's a pitting problem, then depending on the severity of the pitting, they may be saved, but welding is not the answer for pitting.

[captainkirk]

Yep, just a pitting problem.

One of the rims (the Fiat one) about 15years ago, was damaged in a curb crash, (cracked the edge of the rim) and was fixed by a wheel place. I wasn't happy with the work done on it (they lathed it to a different profile), but have lived with it since (drove the car around all that time).

This question was really two fold. One - can something like this be attempted by a dope like me (for future reference), and two, the pitting problem.

Sure i can use putty on the pitting problem, but thought I would ask about welding them first.

I always new that welding these things is not for the backyard person, but thought I would ask.


Welding Magnesium by a "dope" not recommended.

Welding to fill pits on a magnesium rim not a good idea.
If they are to be painted then use a plastic filler, if you want to polish/leave bare then welding will not be the same color and will look like sin dipped in misery.

My.02 is to fill and paint.....enjoy a cool one.
(in that order of course)

Advise worth what you paid for it. :grin:
Kirk

[Bambi]

In my post I stated that many aluminum alloys have trace amounts of magnesium. Its part of the recipe that they get different characteristics in aluminum. It doesn't mean you need to be concerned about welding it. Magnesium wheels or mag alloys are a totally different animal.
I would do some more homework on those wheels, by contacting groups that would be in the know, when you said Fiat, I have widened Fiat wheels for racers and the ones I worked on were aluminum. Not gonna say yours are aluminum, you have to determine that one my friend.
As for pits, the problem becomes when you attack them, do you open a can of worms, some castings when you go after a pit you open a crater, a lot of castings are porous.
I would assume that yours are of good quality, considering my experience with Fiat wheels, that is only my assumption, not gospel.
A lot of the wheel places in the states, instead of welding minor pitts will grind sand and polish the wheels. Welding is a last resort, one important factor is color match.
Now if an animal of any kind even a mouse decides to take a leak on magnesium wheels, its all over but the cryin. The wheels will become blackened and no amount of cleaning will ever take it away, you will clean it and it will come back, magnesium is very porous, soaks urine up like a sponge. So is anyone has real magnesium wheels and see a dog gonna do his thing on your wheels, do what is neccessary to protect your investment.
If your pitts are not deep, then clean them up, most of the shops up here, just chuck them in a lathe and take a skim cut to remove surface pitts and know the nature of the wheels they work on. Something old or rare could become a nightmare or a dream. You'll have to dance with the fiddler down under.
Good Luck
Bambi