Mike, I have a yellow metal footrest hanger. I inherited it with the project parts I purchased. I dont think it came from VOC Spares, it was too badly machined, they would not have let it through the quality system. It was during re-machining that I discovered the yellow under the zinc plating. In all fairness, it's not my favorite material for that job either, but it keeps my foot off the ground and provides a place for the brake lever to pivot.
I made alloy spacers because I have weight fetish & they are non standard length on my special. The tapers bite adequately, the pegs dont come loose and move at all.
Clearly, heating & straightening the original steel hangers has no deleterious affect on their metallurgy, they can then be safely re-plated.
What I haven't worked out with foot rest hangers yet, were the originals cast or forged?
Not that it matters, my next pair will be fabricated from steel machined ends welded to tube so I get some extra length.