Powdercoating and wheel failures?

[UserX]

Has anyone ever heard of this, or see it happen? I was reading this thread on another board, I think it's some kind of urban legend.

A google search pulls up some discussions, but no hard evidence.

I mean the paint is cured at 350-450*, not like that is going to change the properties of a wheel, they prolly get close to that temp on a road course.

Thoughts?

http://www.frisco-online.com/forums/showthread.php?t=774695

[Lason]

I would love to see a failure and proof that powdercoating had anything to do with it. I agree, thats total BS!

[black50]

never heard of it and i dont see it happening

[Baron Von Crowder]

complete horseshit. Almost all factory wheels are powder coated, and all reconditioned wheels are powder. If it was true, we are all riding around on ticking time bombs.

[thesource]

Sounds like bullshit to me as well.

[Strychnine]

The most popular Al alloy used is 6061-T6. The T6 indicates the alloy has been heat treated. Reheating can relieve the temper.
6061-T6 forgings (and extrusions) are heat treated at 350*F for 8 hours (320*F for rolled or drawn parts). Any time spent over that temperature can cause material property changes, though they may be small changes if the temp excursion is for short period.


I did some reading on this in the past and came across this:

Re: Al 6061-T6

At 400°F the reaction rates are pretty quick. Starting with the T-4 condition full hardness (T-6) can be reached in less than an hour. If you're already in the T-6 condition the alloy would overage quickly and you could see a measurable change in mechanical properties. The big effect would be a loss of ductility.

Things are much better at 340-350°F. If you can process the coatings at those temperatures the alloy would tolerate close to an hour. For example if you start in the T-4 condition a vendor would normally heat treat for 6-10 hours at 350°F to get it in the T-6. Sticking another 40 minutes or so onto the time at temperature for your powder coating wouldn't result in much of a change.

Not implying that your wheels will definitely fail... just pointing out that from a materials standpoint, you are making a discernable change.




It's just internet BS, but if you really wanted to discuss the specifics of wheels and not just generic material samples you could get some SAE standards and papers on the subject.

ex: http://standards.sae.org/air811c

Disposition of Wheels Which Have Been Overheated

Product Code: AIR811
Revision Number: C
Date Published: 2006-02-09

Issuing Committee:
A-5a Wheels, Brakes And Skid Controls Committee

Scope
The development and use of brakes with high temperature capabilities has resulted in instances of tire and wheel failures which were attributed to excessive brake heat. These instances have led to the establishment of more stringent wheel requirements and the addition of heat shields, safety devices, auxiliary cooling devices, brake temperature and low tire pressure indication systems.

This SAE Aerospace Information Report (AIR) has been prepared to assist those who are concerned with the removal, inspection, and disposition of magnesium and aluminum wheels which may have been subjected to excessive temperatures.

Even w/ my SAE membership a copy of that paper is still over $50 though, LOL.