Metallurgy related question...

XJsavage

XJsavage

CounterCulture
Joined
Aug 15, 2009
Location
Lyle's Ford SC
And possibly some welding tech too. :rolleyes:

Aluminum wheels in particular.
When talking automotive passenger car wheels, how does one go about determining the alloy that was used? Are their stamps anywhere on it?
I've heard aluminum wheels called "pot metal" and some just call it "cast". Is there even a difference?
I remember a friend of mine had a Jaguar (I think) wheel crack one time and called around for days looking for someone who would even attempt to weld it, found only one which happened to be a older local man that's built custom-equipment trailers his whole life and recently passed. Wheels held up fine for years.
The main reason I'm asking is because I'd really like to add rock rings to a set of aluminum Superduty wheels, probably just on the outer lip and material would be either 3/8" plate or perhaps even solid stock. Seems like chipping is the downside to any aluminum wheels so I'm wanting to prevent it.
As far as welding it, my understanding is that aluminum becomes brittle after it's welded. I've seen myself where material surrounding a weld breaks from a change in temper. Obviously, I don't want anything to do with that noise, so let's say I did a 1/2" diameter piece of solid 7075 (or unless a softer 6061 would be better(?)) aluminum and formed to fit the inside outer lip of the wheel, my plan of action there would be to only run uniformly staggered beads around the weld area unless there's a better method. If my thinking is correct, that would allow some stress relief in an impact situation so the two alloys aren't fighting each other, but still able to work together.

I also wonder too, which welding process would be the best. I have ACTIG, stick and Pulse MIG ready at hand, but I'm wondering if I should use the more focused heat and smaller bead of the TIG, the wider and less intense spray of the MIG (argon shielded), or the penetrating power of the stick?

I can also pre-heat, re-heat, and the like with walk in ovens.

:p
I'm buying. :beer:
 
Here's a view overall of what I've got. '03 Excursion wheels or something like that.
IMG_20180401_114106217_BURST000_COVER.jpg

I didn't have any 1/2" solid Al laying around, but here's a stainless piece to give an accurate size refference. The thickness of material around the wheel lip is a generous 3/16".
IMG_20180401_114147298_HDR.jpg

And I could still use plate rings here. The solid round is very affordable and easy to handle. The aluminum plate, I'd have to cut, which is not a huge deal, but the price on a whole sheet is in the neighborhood of ''oh hell nah", taking into consideration what little I'd use of it.
 
XJsavage said:
I've heard aluminum wheels called "pot metal" and some just call it "cast". Is there even a difference?
Click to expand...


Pot metal has nothing to do with aluminum casting or aluminum wheels. Pot metal is zinc, with some other metals mixed in (sometimes a few percent aluminum, etc.) for whatever desired properties. Pot metal is what stuff like die-cast Matchbox car bodies were made of, low melt point and easy to cast. Anything that is made of cast metal (whatever alloy it actually is) is usually called "pot metal" when it breaks. So if someone breaks a cast iron bracket or whatever, you usually hear "cheap piece of shit pot-metal bracket", because someone doesn't know what they're talking about.

There aren't usually alloy markings on a cast wheel, usually just the standard date code, heat treat batch, mold cavity number, stuff like that. Alloy would/could be proprietary, and there is no reason to display it for quality control or lot/batch tracking reasons. Cast wheels are usually heat treated after casting.

Those SuperDuty wheels are probably forged based on what vehicle they are for, although I'm just guessing.

Are you planning on using these on the street? I know people have welded alum rock rings to alum wheels before, but my comfort level with welding to alum wheels is pretty low, especially around the bead seat area. This is more than something like filling/filing some cosmetic curb rash damage on the outside edge. On the plus side, that outside lip isn't nearly as structural as the bead seat area that it attaches to.

My summary: Sketchy.
 
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Use a dissimilar allow to weld. 60 series alloy would be plenty strong for the base material. All aluminum aneals when welded. Gets softer and more ductile in the weld area. Aluminum crack after or while welding for two reasons. One matching the base metal too closely. Aluminum is one of the few alloys that doesn't break down and fully disolve...it is described as a solid solid but an alloying weld. The other reason is the heat carrying traits. The thinner section shrinks and cools drastically compared to a thicker section. It actually tears itself into. This is why fusion welding is not highly recommended except for non loaded thin profiles at best.
Preheat, keep warm and cool slower the thicker it is. Remeber a lot of manufactures reinforce the outer bands with internal bands of other alloys for strength. I have encountered these layers repairing wheels.

I would personally use GTAW for the control and ability to clean and weld. Its liable to outgass or pin hole some. Forged seems to weld better then cast for the obvious reasons.

Spray tranfer MiG would be efficient but likely high in porosity

Surface Tension Transfer MIG would be excellent but I'm still learning on it.

Here is a link to a very well written article.
aluminum filler alloy selection
 
Viola, the two folks I was hoping would chime in just did. :)
Thanks for clarifying the whole pot-metal.
I'd love to know whether these wheels are forged or not. One point that was brought up by Joe Stuyck about this potential project pertains to the anodized finish that's on them. Once welded, without reanodizing the entire wheel, I'd run into oxidizing issues with the unprotected aluminum. A good solution to that would be the application of a clear powder coat. But of course there's the issue with more added temperatures from being in the oven, which would be in the 300 degree range. I'd have to look up the chart to get exact details. Heat and aluminum don't go well together to my understanding, so the less I have to keep applying heat, the better. I would think.
 
I have noticed a few wheel companies out there, Champion, TR, OMF, do beadlock conversions on aluminum wheels. I'd be extatic to sit down with the right folks within those companies to pick their brain a little.
I'm not opposed to doing a full beadlock conversion on a set of these after seeing how Trailgear builds theirs in ring segments rather than full rings, which saves a shit ton of material. That would also be great practice for me on water jet, and I can't turn away any of that.
 
A large majority of aftermarket wheels aren't anodized, and neither are most OEM wheels. Anything that's painted or clearcoated usually has something like a surface conversion coating, usually a chromate (or chromate-free these days) conversion coating, or some other type of passivation coating. It's cheaper than anodizing, and some alloys aren't easily anodized depending on their alloying elements (like high copper alloys).

Anyway, don't worry about the anodizing, as there are easy ways to take care of the corrosion protection..

Also, powdercoating temperatures aren't nearly high enough to cause problems with aluminum usually, which is why powdercoating is used on many/most OEM wheels. The prep under the powdercoat, and keeping the powder film intact, are the most important parts for corrosion resistance.
 
@MarsFab welded some structural cracks in aluminum wheels for me once. It was cracked bad enough to leak air. Balanced and ran smooth for months after.

I'm not sure what filler he used, maybe he can chime in.
 
Any existing coating will have to be cleaned in the weld area and haz area. Aluminum must be clean with no contaminates...or at least extremely minor. If it is coated it's not going to perform well at all until etched, sanded, stripped or what ever needed to get to clean metal.
 
WARRIORWELDING said:
Any existing coating will have to be cleaned in the weld area and haz area. Aluminum must be clean with no contaminates...or at least extremely minor. If it is coated it's not going to perform well at all until etched, sanded, stripped or what ever needed to get to clean metal.
Click to expand...

That's especially important for anodized parts, because anodizing is just creating a controlled oxidation layer.
 
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I’d weld it in a heartbeat.

Ac-tig with preheat.

Better welding with 3003 or 4043 plate, 6061 welds better than 7075, but don’t
Weld as well as 3003/4043.

Either way I’d use 5356 filler, clean and preheat.

Also run the tig torch around a few times on HF before making a puddle just to clean/pop the oxidation off.

You can weld through the anodization if it’s there, with a slow definitive pulse and throwing wire in when it goes to the high amperage side. This is how you weld boat t-tops and rod holders that are anodized.

Otherwise clean as best you can first, flap wheel, stainless wire brush, scotch tote, acetone etc.

If you wanted to convert to bead locks I would just get a ring cut from whatever plate and use 5/16 nutserts or nuts on inside.




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If I were to weld beadlock rings to any aluminum wheel there is no way I’d use a wheel that doesn’t have enough factory face for the lock ring bolts to be drilled and tapped into the original wheel face regardless of how well I felt about the finished weld structure. I feel pretty confident in my welding abilities on everything..... except aluminum that isn’t brand new lol. Ron’s wheel he’s referring to was cracked pretty bad. It took a lot of work to burn out all the contaminants in the crack. Cleaning, welding, grinding, cleaning re-welding, grinding, and re-welding... it took many tries to get the finished weld clean enough to not be porous. I put a lot of heat into the wheel, much more than I would have liked.
I literally hate welding aluminum and I don’t ever trust it when it’s done. I’ve welded fuel cells that welded perfect but cracked along a weld seam months down the road. The problem with it is that it work hardens and becomes brittle. Aluminum trailers always crack in time along weld seams, fuel cells almost always crack in time. It is the most humbling material I’ve ever seen. No matter how good it seems when it’s done it can’t be trusted.
If you must make those wheels beadlocks, have the face machined flat, weld on the ring. Then drill and tap the bolt holes through the rings and into the surface of the wheel.
Minuscule amounts of flex in the weld will make it crack, just like bending plastic back and forth. It gets hard and eventually cracks. At least with the redundancy of having the bolts go through both layers you’ll have the added security.
I’m no metallurgist but I can tell you from real world experience that a simple 3/8” thick ring welded only around the outside of the wheel like a conventional weld on steel ring will never suffice.


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@MarsFab
That's a different perspective that I like. I may very well look into that actually. There's a substantial surface there to work with too. Would welding in a centering ring be a consideration you'd take in, or would it be better to have that machined into the outer ring? Also, what's a good bolt size and thread count to look at tapping for?
 
As I'm looking at it, I could very well possibly dodge having to machining it flat if I were to cut and weld an inner ring that sits perfectly down on top of the second transition down, which appears to be perfectly flat already, but I'd have to further examine it. I'd still have a bolt area just under an inch wide where I could go through both material. That is if I got lucky and the bolt locations landed just right.
 
If there’s enough material there you could potentially have everything machined into the face of the Wheel and never need to weld an inner ring on but I doubt that’s possible. I’ve honestly never looked close enough at one to see.
But yes if you have the ability then I’d have a centering ring/anti coming ring machined into the outer piece. How many bolts do you want? Less than 25 I’d do 3/8” more than 30 you could probably get away with 5/16” probably and while you’re at it machining the outer ring go ahead and counterbore the holes to accept a socket head cap bolt and protect it.


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Just make sure when having threads through multiple layers, that the layers don’t delaminate when tightening under load enough to change the thread pitch.

Also look into steel thread inserts that can be installed into the tapped aluminum, like a helicoil but much longer


I’d honestly look at welding a rock ring just to protect the rim of the wheel and then inner air locks for bead retention. I just feel like by the time you convert these to beadlocks you could add rock rings and inner air locks.



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Absolutely. Time spent on this would be spanned over months realistically. There's tasks involved that I'd have to get very proficient at before rushing into it, but in the meantime it's an exhilarating rush just keeping kick-ass plans floating around. Luckily these wheels are still abundant yet not very sought after because of it's very narrow window of vehicle applications.
Looks like I'm gonna be stockpiling a few more sets. :)
This project will keep me occupied for a while.
 
If you tap the holes.....make sure it's never in weld metal. Make sure it's is well enough away from the Heat Affected Zone. All aluminum welds soften the base material. Chris is right the alloy itself does cold work. This is true of almost all alloys. Espeacially malleable types. When producing sheet and roller thinning after so many passes it has to be annealed. On all bead lock aluminum wheels this is why the cross section is so beefy. I second inserts. The biggest reason is for reuse of the threads for mount and remounting, gaulding issues and such.

As a note any welded aluminum structure such as a airframe or bicycle frame is retreated as a unit to regain hardness.
Common Design Mistakes in Aluminum | Lincoln Electric
 
If you're going to use a tapped hole, use an insert like a Helicoil. We actually do that as standard practice in many/most of the aluminum parts we use, even parts we buy from other suppliers. Receive the parts, check them over, send them to the machine shop to get Helicoils installed. Many parts come with inserts already installed, if frequent insert-remove cycles are part of the design. In a high strength application, if the fastener is going to go in and out more than once or twice, I'd always opt for the steel threads and larger diameter engagement of an insert.

Standard available insert lengths are fine, as there is little to no advantage to using anything longer than 2d (2 times the diameter of the fastener) in aluminum.
 
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I don't know about wheels, or welding aluminum.
But I used to work in the Aluminum industry.
If you have access to walk-in ovens, you're golden.

Pre-heat in the oven , weld what you want.
It's gonna work harden, like Marsfab mentioned.
Immediately put it back in the oven. We annealed aluminum at 1600-1900 degrees, depending on the mix.
bake it long enough for the heat to be even throughout the metal, turn the oven off and walk away.
Leaving it in the oven to cool to ambient temp is best .... but our ovens opened at around 900 degrees.

Disclaimer: I was not an oven tech. I'm not an engineer. But I had to deal with the metal going in and coming out of the ovens.
What I explained is the process as I saw it.


Matt
 
Just use steel wheels. Sounds like much less of a pain in the ass.
 
Jeff B said:
Just use steel wheels. Sounds like much less of a pain in the ass.
Click to expand...
The 16" steel SDs I just took off are getting put to use. ;)
That's the first impression I got when I saw them the first time was "damn, these are very well built". And cheap. I've done a many weld-on steel wheels in the past so I've got a plan for these. At the same time, I could expand venture into the higher tire availability sizes of 17 and 20 in the same OEM vehicle application line (which I don't have a reason to stray from; that being 8 on 170, hub centric). Plus we have ring kits already programmed for 17 anyhow. I'd also do something crazy and look at the options of stainless outers. Just a thought.
So I'm really just collecting information and ideas on things still new to me somewhat and extremely gracious for any knowledge I can obtain.
:beer:
 
Lizooki said:
I don't know about wheels, or welding aluminum.
But I used to work in the Aluminum industry.
If you have access to walk-in ovens, you're golden.

Pre-heat in the oven , weld what you want.
It's gonna work harden, like Marsfab mentioned.
Immediately put it back in the oven. We annealed aluminum at 1600-1900 degrees, depending on the mix.
bake it long enough for the heat to be even throughout the metal, turn the oven off and walk away.
Leaving it in the oven to cool to ambient temp is best .... but our ovens opened at around 900 degrees.

Disclaimer: I was not an oven tech. I'm not an engineer. But I had to deal with the metal going in and coming out of the ovens.
What I explained is the process as I saw it.


Matt
Click to expand...
Thinking like steel...
This would be a full anneal or at best normalizing. At that high of a temperature and for that long of a soak the part is going to be quite ductile. Slow cooling after full solutionizing encourages larger grain growth. What where the parts funtion? Was this the last step? It is not uncommon for parts to under go this process as the start of a full heat treat. The one you described would return almost any alloy to a normalized state. However if it is an age hardening alloy, like a lot of aluminum this soak and slow cool allows those particles to react and precipitate to a harder structure. Those temps are quite high when compared to steel in the iron carbon phase diagram.
Screenshot_2018-04-02-09-31-08.png

Those temps would fully solutionize about any carbon steel alloy if soaked for long enough. Roughly one hour per inch of thickness.
Aluminum does need different ranges, I wish I had a related chart. We teach more about the ferrous metallurgy. But it gives you an idea of how heat treating works. I'd like a full study in alluminum.
 
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The metal was used to make hermetic lids for food and medical industry.
K-cup and yogurt lids .... med bottle and blister pack.

Like I said ... NOT an engineer. .... just observing the process.

Matt
 
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