Tig welding alloy wheels

[moggywelder]

I've been practicing welding alloy wheels but I don't know wot grade of tig rod I'm using what would be the right grade. Thanks

 

[Wozzaaah]

Are you repairing cracks or just filling in kerb damage?

 

[Richard.]

That was just the Q I was gonna ask.
If you are intending to weld a cracked wheel u open yourself up to all sorts of possible problems in the event of a failure.
I wouldn't do it and it's right up my street. Kerb damage again can be risky business and I'd carry out a crack test first to be sure it's just a scuff.
If you just have a scrap wheel you want to weld on and not use then go nuts and use any filler you like but if you intend on making a repair I'd send it to a wheel specialist who has the gear and more important the insurance cover if it goes badly wrong.

 

[moggywelder]

Thanks for the quick replies. It's for a crack repair for my self for a wheel I'm going to use as a spare I bought a wheel from the scrapyard and welded it to death. And I'm confident I can do a good weld, the specialist had to start somewhere. Thanks again

 

[Wozzaaah]

Seriously, scrap it and find another or give it to a specialist to do the repair.
It might only be a spare wheel but if it ends up on the road a failure could cause fatalities.

 

[Tinbasherdan]

Thanks for the quick replies. It's for a crack repair for my self for a wheel I'm going to use as a spare I bought a wheel from the scrapyard and welded it to death. And I'm confident I can do a good weld, the specialist had to start somewhere. Thanks again

No offence mate but the place for anyone to start is not on a component that, if it should fail, could end in fatalities. It may sound callous but frankly if you wanted to do it and went and killed yourself after it failed it wouldn't even register on the give-a-toss meter for me, however there is very real possibilities that you could wipe out others in the process, and I find that wrong on many levels. Throw it in the bin and buy a good one

 

[Maker]

There's a lot that goes into casting an aluminium alloy wheel, it's so much more than tipping runny metal into a mould and waiting for it to go hard.

imo a weld repair just isn't safe...

I was going to say this, IIRC, they're cooled in a special way such that there is a lot of huge I internal stresses that make it stronger. Welding it will never get it the same.

 

[balmerchris]

Aren't newer alloy wheels made under tension? So store a lot of potential energy, if you weld it that could effect the strength. I heard or read somewhere that if you cut one in a bandsaw it would fly apart because of the tension that is "cast" into it.
All of what I have said could be bull squirt so just ignore me.

 

[balmerchris]

I was going to say this, IIRC, they're cooled in a special way such that there is a lot of huge I internal stresses that make it stronger. Welding it will never get it the same.

Beat me to it maker.

 

[hotrodder]

Internal stresses aren't so much by design but just what happens when you make stuff. Differential cooling is more about trying to minimise these stresses as, left on its own, different areas of a casting or forging etc will cool at different rates due to variations in wall thickness etc

Bottom line is that the best and most experienced welder in the known universe cannot weld an aluminium wheel without locally ruining it metallurgically. Many (most?) alloy wheels ARE heat treated, both solution treated and artificially aged. As soon as they're heated above the artifical aging temps (ballpark of 180ish Celsius for the common flavours) the mechanical properties start to change, and not for the better. If the wheel in question was flowformed rather than a 'straight casting' then the properties will be reduced even more as flowforming is akin to forging i.e. it imparts a grain structure improving mechanical properties over the random grain structure of a raw casting or weld.

http://www.procast.ca/alloy-information-aluminum-a356-0.php lists mechanical properties for a common flavour of cast aluminium in the as cast condition as well as solution treated and aged. Note the yield strength more than doubles and the % elongation (ductility) increases after heat treatment...

Wheel specialists painters* with a TIG get away with repairing alloy wheels because 1) like everything they were designed with a safety factor and 2) if (often when) the repair fails the wheel usually just cracks again and said crack(s) are discovered when looking for the source of the slow puncture if they aren't picked up sooner (before the cracks grown into the bead seat) during a service or MOT etc

There's several threads about the subject scattered around the forum, here's one of them that goes into a bit more depth regarding the flavours of aluminium and common heat treatments used by various different manufacturers... http://www.mig-welding.co.uk/forum/threads/cracks.27163/#post-297002 I didn't include much in the way of links in that thread as the articles in question are always moving or disappearing as manufacturers tweak their sites but here's one from MB whose wheels are made by various different companies including O.Z. Austria AluGuss aka Borbet, Ronal, Mahle (i believe) and maybe only older/forged stuff Otto Fuchs. Basically the same suspects that make wheels for most of Europes car manufacturers http://media.daimler.com/dcmedia/0-921-1285724-1-1287085-1-0-0-0-0-0-0-0-0-1-0-0-0-0-0.html

Ignoring all of the above there are a couple of filler wire alloys specifically made for the repair of the common AlSiMg and AlSiCu castings. They're harder to find than unobtanium. From a metallurgical POV (solidification and liquation cracking) a 4xxx series AlSi wire is the best choice of the commonly available flavours. Not the lightest of reads but this explains why https://app.aws.org/wj/supplement/04-2005-CAO-s.pdf

* not having a pop at painters, i can't paint to save my life but many wheel 'specialists' are either totally ignorant or plain liars as it's not uncommon hear nonsense like the wheel is good as new or the weld is stronger Maybe they've never heard of a HAZ

 

[normspanners]

for some reason my words disappeared??
I did put I think this type of banding is taking things a bit far

 

[doubleboost]

It is only a spare until you put it on to the car
I could repair loads of alloy wheels but I would not take the chance on one failing

 

[Richard.]

I'm asked even begged quite often to do a 5min crack repair on a whacked rim. I'm happy to lose a few quid and turn em all away.
I don't know enough about the material and although I've heard of success I've also heard of failures. I'm sure the failure most of the time would be found before the worst happened but I wouldn't want to take that risk.
I'm a time served tig welder and most of that time was with aluminium. I'm not gonna weld a wheel for anyone.

 

[Maker]

I'm asked even begged quite often to do a 5min crack repair on a whacked rim. I'm happy to lose a few quid and turn em all away.
I don't know enough about the material and although I've heard of success I've also heard of failures. I'm sure the failure most of the time would be found before the worst happened but I wouldn't want to take that risk.
I'm a time served tig welder and most of that time was with aluminium. I'm not gonna weld a wheel for anyone.

Good policy. It would be you paying out if someone were to have an accident caused by a repaired rim.

 

[moggywelder]

No offence mate but the place for anyone to start is not on a component that, if it should fail, could end in fatalities. It may sound callous but frankly if you wanted to do it and went and killed yourself after it failed it wouldn't even register on the give-a-toss meter for me, however there is very real possibilities that you could wipe out others in the process, and I find that wrong on many levels. Throw it in the bin and buy a good one

Advice taken its now in the bin.

 

[Richard.]

The paying out bit would be the least of my worrys (although I couldn't afford to be sued for thousands) I'd be more concerned about the people driving and the kids in the back if it was to fail very badly.

 

[Rrunnach]

I'm asked even begged quite often to do a 5min crack repair on a whacked rim. I'm happy to lose a few quid and turn em all away.
I don't know enough about the material and although I've heard of success I've also heard of failures. I'm sure the failure most of the time would be found before the worst happened but I wouldn't want to take that risk.
I'm a time served tig welder and most of that time was with aluminium. I'm not gonna weld a wheel for anyone.

Ive done a few over the years, never had any comebacks. Its alloy, nailed with tig and, a dawdle.

 

[normspanners]

for some reason my words disappeared?? on the above u tube vid

I think this type of banding is taking things a bit far

 

[Chris Stevens]

Not sure if anyone posting in this thread is aware of the fact that all of the major wheel refurbishment operations here in the UK, offer crack and dent repair on alloy wheels?

 

[Hitch]

Whenever I get asked to do them my normal line is, "If it was mine, I wouldn't bother. Have a look on ebay, probably get a replacement for the same as it will cost you to have the crack welded up."

Its probably about 50/50....some still want it done, some don't.

I did two old Audi rims not that long ago, really didnt want to do them as they were so badly cracked.

Normally grind it out well, and run some 5356 in there with the foot pedal if i really have to.