Re: Stainless steel vs. anodized aluminum...

Posted by Fish'n Jim On 2018/8/16 20:48:59
I would check the parts documentation first.
Since you don't want to do destructive tests; mostly visual,
If there's whitish powdery solids on it in areas of corrosion, it's most likely aluminum. Stainless tends to rust stain or get a film.
The stainless will most likely stay brighter longer, so if it's maintaining its shine, it's probably stainless. The thickness may also be a clue. The aluminum would be a gauge or two slightly thicker. Aluminum is a bit softer, so a pin prick or scratch on the back side. Stainless will resist.

You can usually just tell by eye and feel, and how its made, but that takes experience. The stainless would likely be used in smaller accent trim pieces, and the aluminum in larger, like grills, wide splash panels. But depends a lot on the vintage which is not given. And cast vs rolled. If it's cast, its most likely not stainless, but could be other non-ferrous alloys. You can polish on the back/non-showing side and see how it goes.

Aluminum will react to dilute sulfuric and stainless won't but that's destructive, if you don't wash it off right away.
Similarly with caustic but it's much more potent and reactive, potentially explosive - not recommended here.

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