I made one of those from aluminium tube which I had lying around.
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Do you have a picture?

Hard to believe a scratch can lead to complete structural damage. Is it High-Ten steel like the rest of the bike?

I think it must be like an eggshell....if intact it is fine but a weak spot will grow over time. As noted before, I had the mark on the front which is the worst place, I think. DK what kind of steel, but it seems very thin, much thinner than other steel posts of this type which i have accumulated over the years and those are much shorter.