I have a couple questions about work hardening 300 series stainless.
Does it get hard enough for something with high strain in a very limited stretch? Something like a fish hook?
When it reaches full hardness does further working make it start to break down and get weaker? How much further working?
Can it be carbon treated for additional surface hardness like on the point of a fish hook?
No I am not planning to get into the fish hook business. Just thinking about things.
If you WANT to work-harden it, look up AISI 302.
Loosely speaking, strain *is* stretch -- change in length per unit length. Type 301 can be cold worked to around 200,000 psi yield, which is quite strong, comparable to a wrench. I don't have data on 302, which is commonly used for SS springs, but I assume it would be similar. Cold working a big lump, like a wrench, to that high a yield would be much more difficult than drawing wire, if not impossible.
Ductility decreases with increasing yield, so, yes.
It can be nitrided, but I suspect the temps involved will undo the cold work.
The rule of thumb for austenitic stainless steels (300 series) is that they can be strain hardened to around Rc 50. This is 'way too low for a conventional carbon-steel fishhook, which runs upwards of Rc 62.
The answer is yes, but the amount varies with the configuration, strain, etc. You'll get local failure in tension where the ultimate tensile strength is exceed. That will have the effect of weakening the whole piece, just like bending a wire back and forth until it breaks.
'Don't know, but I doubt it. The chromium in the steel prevents it from converting to ferrite or martensite at room temperature. I don't think that adding carbon will change that, but I'm not sure. I think you also have to reduce the chromium content.
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