@KAMON Knives I'm all excited now, once again, which makes me wonder.
1. What does "rokkaku hanmaru" mean? Never heard this before.
2. What do you think make 1.2519 steel a good choice? People compared it to blue 2 earlier in this thread - how did you end up using this out of all the steels available for knife making? Curious to your thought process and considerations.
3. It's a monosteal - does that mean differentially hardened or "equally hardened" - if it's taken to that high a hardness as prescribed and equally hardened, what does that mean with regard to brittleness/fragileness?
1. To my knowledge rokkaku hanmaru means something like squared top, rounded bottom. That shape refers to the cross section of the handle as the upper part of the handle has 5 faceted surfaces and the bottom part has a round or oval shape.
I'm by far no Japanese expert so that's only what I've learned from several knife related sources and translated it from its German description to English. I'm no English expert either so that could be a bad mix xD.
@drsmp isn't necessarily wrong either as you get the idea from his description, although octagonal means 8 surfaces which a rokkaku hanmaru handles doesn't really have. But I could be very nitpicky right now and also I have no clue if the English translation isn't really exactly what he said ;p.
2. First of all availability plays a huge role. There are steels out there that would potentially be very interesting to the audience here, yet barely anybody here ever heard of them. The reasons for that can be several. For example it could be that they aren't produced anymore, or were ever just product as a small prototype batch and never produced again, or are just not or hardly available in the given market (like some Russian or Japanese steels).
1.2519 at the time was available to me.
The reason for why it was interesting to me in the first place is due to its alloying contents. The analysis of my batch of 1.2519 says it has got C 1.10%, W 1,25%, Cr 1,19%, Mn 0,27%, Si 0,20%, V 0,19%. The biggest advantage opposed to the Japanese aogami is in my opinion that 1.2519 is an oil hardening tool steel instead of water like aogami is. So you can reach full hardness with reasonable slow quenching methods not risking too many fails, yet using full potential of the steel without having to quench in water.
With P 0,012% and S 0,004% it's also reasonably clean which is important for its properties too.
Then of course there are the other reasons like the fine and hard carbides tungsten forms and the advantages tungsten brings in the heat treatment like keeping the grain structure small. Chrome also makes for some carbides and is the main reason in this alloy combo for the steel to be a oil hardening steel.
All those factors make up for me beeing able to harden this steel to ~65hrc tempered for good wear resistance, yet not risking it to be brittle (which many of my customers confirmed).
3. Good question. Since I don't quench the tang and about 1cm of the tang before/outside the handle, technically speaking it's differentially hardened. The whole cutting section of the blade, with the exception of a little spot at the tang is equally hardened though.
What that means
@Jason183 described very good. The blade will be flexible to some extent, but it won't plastically deform.
What I like about the mono steels aspect is that corrosion isn't that big of a problem as it is with mild steel or wrought iron. Some customers even asked me if I accidentally used stainless steel for their knives. But of course a patina will Form on them and all the other precautions necessary for carbon steel in general, are necessary for my knives too.
Long story short - you as a customer won't have any disadvantages from the fact that my knives are mono steel. If anything, in my very opinion, it only has advantages. If you don't perform an ABS 90° bend test with my blade, you won't ever be able to break it in half or anything like that.
But let me state clear that this shouldn't be a diss to a San Mai construction. I know many knife makers that use the San Mai process to reach some quality benefits of their own which they wouldn't be able to produce in mono steel. Want to state very clear that I always just talk about my knives with my methods and processes.
Don’t you mean “let the (squid) games begin”?
With the survivor getting all 40 knives
I mean... We can do that but know that I'm going into this with 40 knives. What've you got?
Maybe good for the people on the waiting list 
