Michael

As Scott said, that's part of what I was trying to say.In other words I'm trying to say that maybe the polymer quenching introduces a state that is a bit more "on the edge" (or unstable) in the quenching mechanical evolution and the energy introduced during the tempering is sufficient to make it evolve further. While the oil or water quench would create a more stable state (obviously I guess) hence not being signifiantly affected by tempering. Now on the metallurgical importance of the secondary transformation during tempering (retained austenite , etc..) I don't know how much of an effect it has and I trust Scott to have a way better idea than I would. Once again it's just hypothetical and an attempt to help maybe a little bit in the aggregation of experience and thinking that is required to better understand what is happening.

I love it! In fact you're just making tools to use your other tools I know the feeling! Guilty! That's a beast though and super engineered too. Thanks keep them coming.

Bare with me here for I have little or no practical experience with this, but I have been pondering and reading everything I could find about this phenomenon for years now. I briefly discussed it with John Verhoeven too but not far enough to reach any deep conclusion. I'm strongly suspecting that the difference in curvature (oil/water) and in this case polymers has more to do with pure mechanical effects than metallurgical one. 1- The "speed" of quenchant is not a single characteristic, it's more like an average. Reality seems clear that in fact each quenchant (due to various effect, one being the vapor properties) has a curve of cooling, i.e. the heat transfer is dependent of the temperature, producing a different speed at each point of the cooling. That in itself makes that a particular physical quenchant, even of differing "speed" (maximum cooling rate or average cooling rate) have a same curve shape resulting in a similar behavior as to the sori. 2- The cooling evolution (speed/gradient within the blade) introduces a combination of stress/deformation into the blades that are essentially a factor of time. For example when the edge contracts due to cooling depending on the state of the spine at that time (temperature, maleability and position relative to perlite cristallisation) that contraction can introduce either a stress loaded perlite, or a mechanical deformation of the more maleable austenite (i.e different sori). Once in turn the spine contracts (and the edge expands slightly due to martensite formation at the same time or not) then the blade behaves again in different manners. 3- The "penetration" of the quenchant into the clay, or relative "wetability" of a particular quenchant and clay combination could play a factor as well (in combination too with the vapor characterisitcs of that particular quenchant) I higly suspect that the phenomenon of sori is identical in essence to welding deformation as well as heat straightening of metal (like in bodywork). A typical experiment is to close a heavy C frame with a thin steel bar (to form an O of sorts) then heat up the thin bar and it will either brake or bend the C frame when cooling. (therefore mostly unrelated to a bigger martensite crystal although that plays a small part). It's all about differential timings and differential states of maleability within the blade section. So in short sori would be a mechanical effect depending strictly on shape of the cooling curve for a particular type of quenchant, and also to some extent its interaction with the clay, the geometry of the blade and the method of quenching (spine first or blade first). In other words we keep trying to find a metallurgical answer (carbides, cristals, etc..) but it's purely mechanical (dilatation/restraint, deformation, stress and timed gradients thereof). If that hypothesis is correct, then the sori variation in polymer quenching tempering could be explained by the state reached being an intermediary state between water and oil. Water deforms the spine more therefore introducing sori, oil deforms the spine less, and polymer creates an intermediary metastable state that tempering temperature is enough to complete/reverse the mechanical evolution (similar to the straightening that is done with a block of hot copper) This is pure hypothetical theory and it's in rough shape, but I'd like the people with much practical experience to think about it and see if that makes sense with what they've observed and know. Anyway just a thought! I'm sure Dr Scott can also deny/confirm and expand on some of this. I'd like to conduct some experiments but I don't have access to metallurgical labs or precise enough equipment to do the forging part without major variation factors (no less, maker lack of repeatability due to inexperience). Maybe it should be taken out of this thread too so as not to hijack, sorry.

I explain to him: Juste des photos. "sneak peek pictures" est un terme generique pour un docu photo, des "photos qui revelent" mot a mot. So yes he's speaking about this kind of pictures. And it's not "from bloom". It's smelted steel from scraps (acier de grappage) or smelted steel from ore (acier de reduction). The bloom is what you obtain after the smelt (la loupe). Incroyable! And he's not telling it all in English, modesty oblige, like he's only been at this for a year or so and it's his first smelt I believe, and maybe his second damas (I can't remember). :notworthy: Thankfully he is now attending one of the best design school (Ecole Boulle) and even though they're not big on ironwork, there is certainly much schooling on design, craft techniques, histories of craft and so on. So this is before schooling and experience, I'm afraid to even imagine what it will become, surely a brilliant future. Well done Arthur!

All those techniques (copper block, torch) are basically an identical phenomenon to what is commonly used in welding straightening and body work (how to flatten a steel panel or take the spring out of it). The principle of it can be best illustrated by a simple experiment. Affix a little steel bar within the open branches of an U made of heavy steel (to obtain sort of a square with one branch thinner). Then heat up the thin branch, if properly done when it's cooled down the thin branch will have been broken in traction or the U will have been deformed inwardly. That symbolizes what is happening within the blade (thick part is hard edge and shinogi, thin branch is the spine). The exact principle of why it works has to do with expansion, stress and deformation and relative malleability at different temperatures. Bottom line it should work but is a tricky thing to get right. I have no experience myself with a blade and sori, but I've done the other ways (steel plate, and welded piece) many times. Same, it's tricky to get right but it works.

How about some like this (different process, induction)? http://www.richieburnett.co.uk/indheat.html

I just saw bearings by the unit at Orchard Hardware Supply the other day. I don't know the dimensions, but it seems about right.

Well here is one: http://www.multiplaz.com/about.php Very interesting for all kind of processes. I wonder how good it works.

From my notes, I never tried them but here it is if you want to try: To free rusted parts, a coast guard trick, heat up the part, put parrafin wax on the hot nut that will melt and sip in by capilarity. Someone else mentionned PB B'laster that you get at auto shops, soak and tap every couple hours until free. Both supposed to be way better than WD40.

Smart and Final 40lbs bag for $12.99 and that's L.A. Mesquite charcoal.

Dan, Randal, how about this, it may help. If you know already, never mind (click "tsukamaki", there is even the link to the pattern): http://www.zatoichi.de/katana_01/index.htm

Great! What metal did you use?

Some clay recipes do not include charcoal and they seem to be effective too (I guess satanite is one of them).

I think what Tyler was asking was a slightly different question. So I will attempt to answer that. There is no "equivalence" between sets of quenching medium (water, oil) and quenching temperature. In other words a specific steel requires a specific quenching temperature (critical (Ac3)+50) regardless of the medium used for quenching, and a specific minimal cooling speed to obtain transformation. While steels quenchable in oil can certainly be quenched in water, it introduces stress, deformations and even cracks. If the oil cooling speed is sufficient for the particular steel (100% martensite transformation), there is no gain in hardness by using water, only drawback of mechanical stress. If a steel requires cooling speed of water, a slower quenching medium (typically oil) will not do. To know the specific quenching temperature (and recommended medium) for your particular steel, there are tables and material sheets.

Well here is my setting. As much as I'm traditional, I'm not about to bend over and tuck in like that. The stump has a step in it, and that holds the stone just fine. And because of the stump, I can put my legs to either side and have a very similar posture to the japanese one without hurting. The other thing I've seen is sort of a wide saw horse or an old carpenter shaving bench with a ledge to hold the stone.