QUOTE(GBM @ Jan 5 2008, 01:05 AM) [snapback]468116[/snapback]
Nails usually have pretty good steel in them.. A different technique with regards to heating, working while soft, reheating and quenching and tempering ( slight heating stopping at proper color ) should fix any problems.
However, if that is not the cause of the problem.... use a concrete nail for your next project.... they have to be of exceptional steel...
Greg
I hope I'm not being confrontational Greg, but here, the nails generally aren't as you describe. I've tried working with the ordinary kind, and they are either no carbon or very low carbon content. As temperability depends largely on the carbon content of the steel, other than case hardening, as Ron has mentioned, I have never succeeded in hardening (tempering) common nails.
Like yourself, I then thought that the superhard concrete nails would be great for some applications I had in mind, and I attempted to anneal them to work on them with the intention to temper them after working. I was quite surprised to find them very difficult to anneal, as they retained most of their hardness and usually broke when bent. So not all steel is created equal in that department, and you just have to try and see what works best.
I will say I have had great success with 'drill rod', a high carbon steel often available in some hardware stores at a reasonable price. It's usualy available in many diameters from 1/8 inch to well over 1/2" (not that we'd need stuff that big often..). Anyway, it works well and holds a pretty good edge when tempered. It can also be hardened to be less brittle than an edge might require, say for a wrench. The beauty of the case hardening Ron was talking about is that it hardens a thin outside layer, giving a great deal of toughness to the tool, but the less brittle center part helps prevent it breaking suddenly under use.
Trouble is, case hardening does require more knowledge usually, but since we're just talking nails here and not expensive items, one could experiment with different techniques and materials. I'm aware of things from slow heating while encased in raw carbon, to commercial coatings and heating.
I'd be interested in knowing what technique you used Ron - care to share?
Regards,
Gerry