The annealing process for most heat treated Al starts at ~450degree Celsius.
I doubt that any powder coating process will reach this. And if they do the only color that they have will be Black.

 

Road wheels are usually made from A356.0, not say 7075 which has a higher anneal temp. A356.0 starts to exhibit changes in its outer surfaces with sustained 350°f at exposure times of less than an hour. Full anneal to O at about 650°. PC cure is around 400°.

Ask any wheel manufacture that makes racing wheels and they'll pretty much tell you the same thing: "unless we PC our wheel, it's not OK".

I have no reason to hold this position other that wanting to keep our wheels strong. If we allowed it, we would certainly sell more wheels as folks would be more inclined to do a custom color we don't offer. I base this recommendation on the information received from a few engineers in relevant fields as well as the engineers at the factory that makes our wheels, which also happens to be a Tier 1 OEM automotive supplier. They say no so I say no.

Anyway, wet paint is lighter

 

^Clear and compelling case IMO. Thanks for posting.

 

Not the PC process temperature is the problem. The surface treatment before PC is bad!
The parts are pc'd at 355F for max. 15 Minutes. After that they cool down.
I do not want to defend Powdercoating. All I want to point at is that the wrong horse is beating.
If the wheels are blasted even before ordinary painting, you will run into the same mess.

 

Rockwell test anyone? That would be one sign of testing whether the heat treatment of the PC process has altered the hardness of the metal.

 

Yeah, but AGING ocurrs at much lower temps, ~350F for 6061-T6, which is what 99% of forged wheels are made of. Overaging WILL reduce strength properties of forged wheels.

 

Aging is long before finished. It's done before the final painting from the manufacturer.

 

Yeah, but stick forged 6061-T6 wheels in an environment over ~350F for a while and you OVERage the material, and strength properties will be reduced.

 

For 15 Minutes??
Anyway, as I have already written some posts before: I have proof for my statement. We found that glass-bead blasting was the cause for a failed aluminium structure part that broked only a few cycles after usage. It was so unusual that we performed further investigations and microscopic visual inspections. We found broken glass particles that had penetrated the surface and initiated a crack.
A sub-contractor of the supplier had blasted (which was strictly prohibited) 2 parts out of 150 and both of them failed...

 

Perhaps more of a CYA thing then anything, especially in this sue happy society.