Totally awesome knife Greg!
If you had hand-rubbed the handle too, I think I'd be in love. That blade just looks AWESOME!
As far as the multiple quenching, from my studying and testing, it seems that the biggest reason for improved performance in knives isn't really all that complicated. For steels like 5160 and 52100 that have enough alloying elements in them that they would be considered more than a "simple steel" (i.e. W1, 10XX, etc.) it's difficult to get all of the alloy to diffuse into the matrix prior to quenching if your heat source is a forge.
Having a past as a personal trainer, I like to think of it in terms of muscle fibers. If you do a set of squats, you fire many many muscle fibers in the legs (predominantly quadriceps, but the entire lower body to an extent) on your first set. But you didn't fire all of them. So you do a second set, and fire those and some more to make up for the increased difficulty after already fatiguing the muscle during the first set. Then you do a third, and fire off even more. (and so on in certain situations). Ultimately you're trying to get as much as you possibly can out of your legs, and you couldn't do it as completely with a single set.
It's like this with the steel...if you can't get the alloy to diffuse in the first quench, then you return it to the forge, get more alloy to diffuse and then quench...and so on. The idea to try and get as much of the blade into Martensite as possible. And then bring that to tempered Martensite after tempering.
I've done a pile of tests on this notion with both my forge and my digitally controlled salt bath. With the forge, where I'm afraid of soaking the blade at temp because I can easily overshoot my austenitizing temp, I quickly quench and find that doing this three times helps me get the grain structure set up fine and achieving full or close to full hardness in the finally quenched blade.
With my salt bath, where I feel comfortable soaking blades (all day long if I like, because I WILL NOT overshoot the desired austenitizing temp), I can get the blades to full hardness with a very fine grain on the first quench. I have tried SEVERAL sessions of multiple quenching blades using the salt bath as the heat-source, and have not found improvement in the final blade. BUT, I will continue to test and find out what works for me.
In the end, these are my VERY humble opinions and could be the most ridiculous thing ever put in print. But it seems to line up with all of the reading and testing and visits with metallurgists I have done so far. Anybody can feel free to post their alternative thoughts on it, that's why I test so much, to LEARN and IMPROVE.
Not trying to hi-jack your thread Greg, I kind of went off there.
Most importantly, that knife ROCKS!!@%*@!!!j
Nick
