..this is just a game at this point to see if I can compare favorably with furnace heat treating.
I never had big trouble with heat treatment, but didn't know why (but it was because of my steel choice of O1 and the fact that I didn't overheat the metal for no reason).
Then, after I was comfortable with what I was doing, I started reading more to see if I could get the grain finer, and much of what I read led me to think that maybe success was just a matter of luck, but that failure was just around the corner. The literature is for long soaks in ovens, which seem to be different than short quick heats in terms of creating issues. If you make plate martensite from overheating, I guess it's one thing. If you make only that due to a long soak and more uniform properties, then you get really fragile steel (O1 is a steel that makes plate martensite if the soak temp is 100 degrees too hot).
Fast forward, I mentioned something to larrin about where to get testing around here, and he said "he'd test coupons for toughness for free". I don't want toughness, I want hardness testing - I want to see that my coupons are within a C point of each other from one to the next, maybe they won't be. i figured I could send him my samples and then beg to pay extra to have hardness testing done (since Larrin's primary audience is knife users, toughness is much more important -being able to baton a knife even though it's 61 hardness seems to be something those guys really like). Larrin answers short answers because people waste his time a lot. I figured if I sent him samples, then I could beg hardness testing because he'd know I wasn't saying I'd send samples and then ending up like 95% of everyone else who fails to show up for the game.
When he realized I was serious and wasn't going to just send him coupons with big sandy grain, then he said he will hardness test the coupons, too. I asked him if I could pay more and send larger samples that would be suitable for a hardness tester and he said he would test the coupons. In order to confirm that I wasn't sending him junk, I snapped two untempered samples (you saw the picture of the O1). Neither of the two forgers who sent him knives came remotely close to those samples - but now I'm curious since I've solved refining the grain, could I be stepping in poop otherwise because I heat the steel well into temps that would cause plate martensite in a furnace.
So, I'll get hardness numbers, and I think Larrin is only interested in hardness of toughness comes along with it (coarser grain often leads to higher hardness, but you can't use it if steel breaks like glass).
Since the coupons can't have their ends ground, I wasn't able to get them on stones and estimate hardness, so it's still a bit of a guess. I don't send chisels out without testing them, or they end up like the ones I sent you quickly (but now that I'm working only with a couple of steels and there's no alloy guess, I haven't had a tool fail to test well for a long while now).
I think I'm in the area where you'd say a good golfer or musician is - that even if I have a minor miss or mistake, it's better than my "good shots" were when I started. This is the zone for hand tool work of any kind, even if it's grinding and heat treatment - to be able to do something well while being partially engaged rather than eye-crossing concentration.
I cannot tell yet if Larrin's initial work with forge heat treatment is intentionally awkward to keep the forge heat treat brigade from turning into a bunch of trolls and swamping his content with nastiness -I think that's probably the case. He's done so much on small furnace cycles and methods that much of his adjustments to manufacturer's numbers leads to better results. He may be intending to do the same thing with forge stuff - I'm not in a position to see where he's going with it or ask him - maybe he knows a lot more and it's going to culminate with a go-to method for forge heat treating (like a DET anneal and then only one or two quick things following that). DET anneal is slow cooling in vermiculite in a steel sandwich to refine microstructure - that's another not-so-viable commercial thing when people don't want to pay much for plain steels in the first place, but it's the kind of thing I'd like to experiment with. I don't need to learn more now, but if more is available in improved results with the same effort or less, I'm OK with that.
(I have no interest in delving into more complicated plate-hardening (air type) steels that require cryo treatment to avoid retained austenite and brittleness, as well as long thermal cycles and then three 2 hour temperings with full cool between. I'd just send them to peters.
But those things do lead to my previous comment to you when you found that the dump knife is capable despite extremely low aptitude needed to harden it to the condition you have it in - how much of what's out there is really given all of that attention? The bos cycle is posted on bladeforums, so anyone can take a whack at it. It's not something you can do in 20 minutes with tempers in a steel sandwich in a toaster oven, and then the resulting comments (just like with 80crv2 and aeb-L) tend to "I was underwhelmed with the fine edge", while other knife abusers are just over the moon.
There are people on that forum who never sharpen knives with anything finer than 220 grit - you can survey and notice patterns about who likes what. Despite all of the testing stuff, larrin prefers driving AEB-L to high hardness, making the angle more acute and working with it as-such. It can literally beat much "better" steels that can't hold up at the more acute angle, and he repeats from time to time that hardness and angle are more important than alloy, but not many people want to hear stuff like that. Sharpenability isn't the universal issue there that it is with woodworking tools, because sharpening is less frequent and only a small part of the group is "slicers" who like a fine edge.