Hand Tools Archive

Subject:
Re: A great and helpful summary...

Rum
Interesting on the vixen, I've never really tried using one on steel but as you say on annealed stuff it should do a pretty good job. Certainly seems like it would be faster cutting than most files! I'm not even sure if I have any.. will have to keep my eye open at the usual sales.

I mostly agree on experimentation, although it is nice to have some sort of control on the results otherwise its less experiment and more throwing mud against the wall (which is admittedly also kind of fun but perhaps less generally educational). Personally i tend to err a bit on the other side and analyze things to death beyond the point of getting anything done (I'm quite sure based on reading your posts that you can't relate to that at all :b ).

I have very limited experience with water hardening, having mostly worked with whoknowswhatium as opposed to actually known quantities and oil is a bit more forgiving. I have used a brine for some steels, the general theory being that you get more aggressive hardening because of less cavitation (and something about temperature transfer which I can't quantify meaningfully other than to say "faster than plain water"). Some people also use various sort of soaps or detergents as surfactants to increase stickiness/and I believe the quench speed. Brine can be pretty fast though, and you don't want to do the "hold it in until the sizzling stops" but more "get it past the phase transition and pull it out quick". I suspect for thinner stuff you're probably going to get less warping and breakage in oil so would probably stick with that unless you have issues. You could thin the oil with kerosene or diesel up to maybe 50/50 if you want to get a bit faster quench.

You can kind of tell if you're hardening to fast by either the steel telling you while quenching (pings, warps, self destruction) or if upon grinding back you find the surface was a lot harder than the core.

Almost all of my work has been in carbon rich (tree bark and coal) based fires which are pretty reducing so I haven't really worried to much about decarbing (other than keeping the piece well buried in the fire). Using the propane setups might well be more of a problem. There is surely some tradeoff between fewer higher heats and more lower heats as decarbing increases with time at temperature but I don't know enough to quanitfy it. At dull red you're bumping the lower end but probably not maintaining heat long enough to get very far into the steel.. probably...

I've also kind of wondered if with the higher carbon steel I might have been inadvertently benefiting from some decarbing. This is all highly annecdotal, but I had more issues with some larger pieces ("bowie knife" style made from a rasp) being glass brittle once hardened before tempering (or more accurately when I double dipped a little to soon.. sigh) whereas I didn't have the same type of issues with smaller stuff. There's some tradeoff between tough and hard there but again lots of unknowns in the underlying material that could have a large affect on the whole thing.

I think that the old hay rake teeth were something really close to 1095, they were some sort of high carbon spring steel anyway. They were kind of tricky because you had to be super careful not to burn them up. Its easier to put a lot of heat into high carbon than it is into low. For instance I could forge weld small (3/8" round) high carbon stuff like rake teeth with a fir bark fire, but you'd have a really hard time getting more mild steel like a horse shoe or the like hot enough in that kind of fire (good charcoal or coal yes.. bark.. not so much). That probably has some implications on the workability of your 1095 vs 1084 samples (not quite sure how 1084 behaves), if you're not hot enough pounding on it to much causes cracking. OTOH I also believe that if you get it hot enough to be plastic then hammer deforming it helps smooth (smear) out defects and inclusions giving you a better grain on the finished product.

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