ClarkSJ

Don't know about cast. But the alloy composiiton will determine the aging temp.

Is there a metallurgist in the house??

turtlehelmet

IIRC they've stated 'cast alloy wheels vary in porosity and surface blemishes from offgassing could occur in the process'

TTschwing

"Found your article most enlightening. A metallurgist friend told me a few years ago that things like aluminum wheel spindles should not be powder coated. He explained that aluminum billet material (6061-T6 ?) changed crystal structure at a critical temperature around 410 degrees F (as I recall). The thrust was that the heating step would adversely affect the strength of the material. Non-structural components would be OK, but not something that "holds the spokes on". The metallurgist is correct. Products like wheel billets, scuba tanks, etc. can be powder coated, but only with powders which cure below peak metal temperature of 300 degrees F. The crystalline realignment at 400 degrees F causes the previous ductile aluminum to become brittle. Imagine the catastrophe when an 80 cu. ft. scuba tank explodes under 3000 psi pressure after an unauthorized powder coat (this actually happened). To my knowledge, all Aluminum wheels and other strength-critical aluminum components are powder coated with these cooler curing powders"

So...The knowledge and skills of the Powdwercoater, along with the proper temps are important... Many wheels are powdercoated all the time...Whether their strength is compromised will depend on the temps used..<ul><li><a href="http://my.execpc.com/~davewrit/Powder.html">http://my.execpc.com/~davewrit/Powder.html</a</li></ul>

MCPaudiTT - DEFCON 1

I DO believe that a proper cooldown period to induce aged hardening would be highly recommended, though. After powder coating, cool to 350 F for 8 hours, then let it air cool. You will end up with 6061-T6 powdercoated wheels.

Heat Treatment

Solution heat treat at 990 F for adequate time to allow for thorough heating and then water quench. Precipitation hardening is done at 320 F for 18 hours and air cool, followed by 350 F for 8 hours and air cooling.


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Forging

The alloy is capable of being hot forged at temperatures in the range of 900 F to 750 F.


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Hot Working

Hot working may be done in the temperature range of 700 F to 500 F.


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Cold Working

Cold working in the O temper condition is readily performed. The alloy is notably less easy to cold form in the T 4 and T 6 tempers.


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Annealing

Annealing should be done at 775 F for 2 to 3 hours followed by controlled cooling at 50 f per hour down to 500 F, then air cool.


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Aging

The aging precipitation heat treatment is done at 350 F for 8 hours followed by air cooling. This produces the T6 temper.<ul><li><a href="http://www.suppliersonline.com/Research/Property/result.asp?FamilyID=2&amp;MetalID=555&amp;Chemical =1&amp;Physical=1&amp;Mechanical=1">http://www.suppliersonline.com/Research/Property/result.asp?FamilyID=2&amp;MetalID=555&amp;Chemica

TTBlack

would be insane, not to mention o-rings and the likes. I understood the process used much lower temperatures, in fact, I thought that one time I read, or someone stated, that certain plastics could be powder coated with proper prep.

Definitely why I go with professionals!

&lt;edit&gt; Found what I was looking for...it was not powder coating on plastic, it was chromeplating plastics with proper prep &lt;edit&gt;

Thanks Steve

Russ Scott

<center><img src="http://pictureposter.audiworld.com/34314/kw.jpg"></center><p>
maybe... but why? when these stainless steel beauties are available at Russ's Suspension World ;-)

Hi Dave!

SpongeBobTT

Not looking to debate ya bud but I've been casting, extruding and fabricating aluminum for 21 years.

You can only thermally treat 6000 series alloys once. To treat again (350 for 8 hours) will substatially reduce elongation... it will get brittle.

TTschwing

And with careful temp controls on Engine plastics, CAN be coated.. Those are generally formulated to deal with some level of heat to begin with..

TTBlack

Long time no see my friend. Going to try and make TT East this year?

Russ's Suspension World...nice!

MCPaudiTT - DEFCON 1

ought to know better than me!