> a low-nickel alloy suitable for contact with skin -- 316L, I think
Now I’m curious: why use any nickel at all? Plenty of stainless steels (including, AIUI, basically all the tool steels) don’t use nickel, and many of them have excellent corrosion resistance. Is austentitic steel enough easier to machine to make it worthwhile?
Shorter answer: We don't know -- those are good questions!
Longer answer: It was 20 years ago, and we aren't exactly metallurgists. IIRC, at the time it was something to do with a variety of "surgical stainless" to focus on the best corrosion resistance combined with something that was somewhat machinable. At the time, I think we were comparing 304 (easier to machine, much worse corrosion resistance) vs. 316 (harder to machine, but much better corrosion resistance). I think looking at metals that we were able to source in partial lengths might have been a factor as well.
In hindsight, one might be able to find something with better properties in a more specialized alloy, but if I had to do it over again, I would 100% be willing to choose the 316L again. I have zero complaints with it, and the corrosion resistance it offers is superb. In 20 years, I've never polished my ring once, and it still has that mirror-finish quality (especially on the inside where it has never brushed concrete).
I rarely take the ring off (sometimes when juggling) -- I don't worry about it and leave it on even when using tools or scrambling up a rock ledge or carrying cinder blocks or whatever. Very occasionally it will get scratches (concrete is one of the few things that has left a mark from time to time), but they're never very severe scratches, and they buff out nice and naturally over time. I imagine that I would be much more concerned about a softer precious metal, and I'm glad I have a more durable ring instead.
Conclusion: 304 and 316 are probably fine, as is 430 (which should be entirely unsurprising due to its near lack of nickel), but 303 would be a poor choice.
For what it's worth 316 is more corrosion resistant than 304 in saltwater environments and I've been trying to find various fasteners made of it for my boat.
Or fastenal, they have saved me a few times with odd requirements. Between McMaster, Fastenal, or even Grainger you should be able to find plenty of whatever you need.
> I imagine that I would be much more concerned about a softer precious metal, and I'm glad I have a more durable ring instead.
Well, you could also just live with the scratches in your ring (if you had one made of eg silver) and declare them part of how it matures with the passage of time. Just like copper gets a patina, too.
(I'm glad you are happy with your ring! I'm just saying that if people decide to be happy, they'll find a justification to be happy with what they have. And if they decide to be unhappy, they'll find a reason, too.)
Now I’m curious: why use any nickel at all? Plenty of stainless steels (including, AIUI, basically all the tool steels) don’t use nickel, and many of them have excellent corrosion resistance. Is austentitic steel enough easier to machine to make it worthwhile?