I posted a thread a few weeks ago asking for tips on welding magnesium, which can be found here: http://www.jalopyjournal.com/forum/showthread.php?t=179502&highlight=magnesium I finally got a few spare moments today to actually give it a try. First off, this post really only applies to those of you who own or have access to a TIG welder....you evidently can weld magnesium with a oxy/acetyline set-up and the proper flux, but I'm not going to go into that here. Secondly, I'd really only recommend trying to weld magnesium if you are comfortable welding aluminum, as it is a very similar process. Also please note that magnesium will burn if ignited, and about the only thing that can put it out is an extinguisher carrying "Purple K" powder. Take care not to strike an arc in the presence of leftover magnesium shavings or filings. There are a lot of opinions and apparently a lot of false information out there regarding the welding of magnesium, so I thought this might give a little insight on the process. I am by no means a expert on the subject, but after giving it a shot, I think I can show you what I did since I had favorable results. Here is what needed to be welded...a pair of early Halibrand small windows that had screw holes drilled in the outer lip. I wanted to weld them up for cosmetic reasons...not so much for structural reasons. The first step to the process is to get the proper filler rod. For cast magnesium, you want to use ER AZ92A filler rod. The problem with this, however, is that it is ridiculously expensive. It's running around $125 per pound right now in Dallas. So if you can find a friend that has some or a welding supply that will sell it to you by the stick, that would be advantageous. I only used 1 stick of filler rod to weld up the screw holes in both wheels. Ok, with that said, the next thing is cleanliness before the weld. Like aluminum, magnesium needs to be clean, clean, CLEAN before you weld it. I used a Roloc Scotchbrite pad on a die grinder to knock off any oxidation on both the top and bottom of the lip. Then, since the holes had been in the wheels for who knows how long, I drilled them out slightly bigger to remove any oxidation that might be hiding in the threads. I also went with one size bigger drill bit at the top to create a bit of a step in order to get the weld to pentrate a little easier. After that was done, I went over the sections that were about to be welded one more time with a fine stainless wire brush. Before welding, make sure that there are no magnesium shavings or filings near the welding area, since it is possible for them to ignite under an open flame. A shop-vac comes in handy here. Here is the wheel ready to weld...but notice the shavings near the center. I removed those before welding. The welder should be set on "continuous" high frequency, and "AC" current....the amperage should be matched to the thickness of the material you are welding. I used a 3/32" pure tungsten with a gas lens on the torch. I strike an arc on the welding table to "ball" the end of the tungsten before starting to weld on the piece. Magnesium really does weld a lot like aluminum...if not a little easier. I experimented with pre-heating the areas to be welded with a handheld propane torch on one of the wheels, but there wasn't any difference that I could see. Pre-heating might be helpful when welding thicker castings, however. You should have something like this when you finish: Here's a close-up: After a quick once-over with the stainless brush, it looks a little better already: I next used a vixen file to dress the weld down even with the face of the wheel lip. You could use a grinder I suppose, but the vixen file cuts the magnesium quickly, and there is less danger of creating gouges in the wheel. A wheel lathe would also be handy here, but if you're like me and don't have access to one, then that's not an option. I next used 120 grit paper on a DA sander to smooth it out. After that was done, I switched to sanding by hand with a piece of 180 grit. With that completed the wheel is ready for polishing or Dow 7 or however you'd like to finish. It's now nearly impossible to tell where the repairs were made. The color of the AZ92A rod is very close if not an exact match to the mag alloy used in the Halibrands. As I said above...I'm not an expert on welding magnesium, but I'm pretty happy with the way the repairs turned out.
Great tech thread. Good point about welding around chips. If the weather is friendly, definitely something to consider doing outside. If that stuff lights up, there's no way for the average guy to put it out.
Nice job Bass. Do you think as the wheel oxidizes that the repair will be more noticeable? Like if you prefer the darker patina, will the repair change color at the same rate as the wheel? Doc.
Thats preety much how i had heard to do it...I would have tried by now but haven't had any reason to weld magnesium...and I had no magnesium to weld.. It looks just like welding aluminum...
Nice stuff Bass. Lately we have welded quite a bit of mag in my shop. I also did a small window Halibrand rework. That one was off a friend's injected hemi front motor digger and was a little used up around the lug holes as well as having a crack in one of the ribs on the back side. I used a carbide cutter on a die grinder to get to the root of the cracks and also used a Scotchbrite Roloc to clean up around the area to be welded. Just a caution here, don't try to bead or sandblast the area to be welded as glass beads especially can contaminate the surface. We use a fresh scotchbrite and or wire brush for the same reason. As noted mag welds as nice or nicer than aluminum (so does Ti). One more caution. Bump up the post flow time a little and make sure not to pull the welding rod away from the shielded zone before it cools enough. Roo
Once again great work. So are those going onto the coupe or for a customer? What is the latest with chassis that you had at the roundup?
You have to admit the Chit welds like BUTTER view pics on my space page.. Mag over anything its like love at 1st Beed in life... Spin that MUTHA ! on a Lathe NOW!..sTILL LOOKS sIcK! .. KILl THE WINDOWS.........
looks good, Were you able to go all the way through or just the face? I hope you saved all the chips so we can have a little bon fire.
Great Tech post. This takes the mystery outa' welding magnesium. I have several mag wheels that need repair. This has increased my confidence level that it can be done safely.
Nice post Bass! I've wondered if a filler rod from a VW block or other sources of magnesium would work. Thanks for the tips.
Bondoboy, Ti is kind of cool to weld but can be hard to keep down the impurities on the back side of thin stuff unless it is done in an inert atmosphere. For heavier material where there is little chance of overheating the back side we usually use a wide mouth cup on a gas lens and crank up the argon flow level to flood the area. Usually stretch out the post flow as well. I did a repair on the wheelie bar on J R Todd's top fuel car last week and it came out nice using that method. Roo
I may need to give this a try. Not me but my welder / fabricator buddy. Anybody know where to order the ER AZ92A filler rod online?
I wonder could you patch the extra lug holes, or did the wheels come that way? I have an old brake lathe I want to modify for repairing and polishing old wheels.
You can't weld magnesium - you'll set yourself on fire & won't be able to put yourself out!! Good job!
Sweet thread Very nice tech. I to had learned how to weld magnesium but I figured it had to be similar to aluminum and hell it was haha. I know that like you were saying it expensive but everwhere I went you had to buy atleast 3lb since it was a special order item and it was only $110 a pound but still haha. Luckly my father is friends with everyone around here and I was able to buy just one pound for $100. I used it on a couple of old quickchange rearends that were magnesium and I still have alot of the bound left over. OHH YEa and alot of new car and truck transmissions are completly magnesium just figured that was a neat little fact to know.
Great tech post Bass. I was hoping one of you guys could answer my questions. I have a pair of 15 x 4 magnesium five spokes. One of the wheels has some pitting on the face. I was hoping my lathe guy could just turn the face like he does the aluminum wheels. Part of the problem is these wheels have a lip around the edge. Then when I told him how much the wheels are worth he got a little nervous. Is there any tricks to turning these, such as what speed to spin them and how much can I take off? Or, can I use your welding technique to fill the pits and then sand them. Anyone have any ideas? Thanks ~ Scott
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