Sounds like a bit of a paradox...though, I do take your point on 400f+ oil, Stacy.
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Brine Quench Revisited...
- Thread starter 69_knives
- Start date
Sounds like a bit of a paradox...though, I do take your point on 400f+ oil, Stacy.
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- Sep 9, 2003
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- 2,361
Sam, I also know that we know each other well enough for you to understand that when I say you must be out of your freaking mind that it is because I know you are just a snot nosed poo, poo head, in fact I am surprised you didnt suggest 400 degree snot! 
But while I dont see it in this thread, I do understand what you are saying about insightful people with plenty of experience, just moving on to greener pastures than many of the conversations on this forum these days. Oh, and as Thaddeus Venture himself would say have a scientastic day!
The most interesting thing about our craft is that you can ask the same question of six bladesmiths and still manage to get six entirely different answers, or explanations, and that is why just trying things for yourself may remain the only certain method of choosing your path. So now I guess I can add my entirely unique answer to the ones already presented. After working with the simplest carbon steels, oil hardening steels, even some air hardening steels, and having completed the circle by working with truly simple water hardening steels in the same forms as ancient and tamhagane steel, I have drawn some conclusions myself. Water works very well with traditional Japanese blades because they are not made from modern steels with alloying. Even the simplest 10XX contains manganese, which changes everything, and it is in all our modern steel. In light of this I personally have no use for water or brine in quenching any modern steel, but I have seen it work well with bloomery or tamahagane steel.
Before looking at the quenchant, in order to fully harden any steel proper austenite solution is necessary. This is the case with any steel, in order to achieve the initial BCT martensitic structure enough carbon has to be in the matrix for that transformation to occur, putting less than .6% to .7% into solution means you do not achieve full hardness. Now how fast you cool things determines how much of this carbon you got into solution stays in solution, but alloying slows that loss of solution allowing slower quenches, but it also increases distortion of the lattice when the hardening occurs. You will notice many recipes for water quenching modern alloys suggest much lower austenitizing temps in order to avoid blowing the steel apart. Lowering the soak temperatures lessens the amount of carbon in total solution and thus lowers the amount of distortion or cracking, this makes total sense when you realize that by not fully hardening the steel you lower these chances. With the simple iron/carbon ancient steels I have worked with there wasnt the same need to deprive the austenite, and subsequent martensite, of carbon and full hardness could be obtained in water without the same fear of self destruction. Simple, ancient steels = simple ancient quenches (water). Modern alloys were specifically designed to allow slower quenches with full hardness and less distortion and cracking, forcing them back into a more severe quench can only be accurately described as driving a square peg into a round hole.
With modern alloys most of the same activities and beautiful hamon features can be achieved with an oil specifically formulated for extreme speed, not any oil but an oil designed to harden modern shallow hardening steels. In know this because I have done it, and I know many smiths who have devoted the time to learn how to get these results with 10XX in fast oils. While the activity can be just as striking, the sori will not. This makes total sense when you reflect on what I have described in the paragraphs above. While full hardness can be achieved the distortion will not be as dramatic due to the gentler quenching action.
I am not a fan of water for anything but the simplest of iron/carbon steels, simpler than any steel commercially made today. I am also dead set against heating any oils except a carefully formulated, dedicated martempering oil. If one interrupts a quench, be it water or oil, the assumption must be made that it is for the purpose of drastically slowing the initial cooling rate, air is an excellent insulator, much better than water or oil, thus simply removing the blade from the quench at Ms is what I would do. If there was clay I also wouldnt want it fouling up my low temp salts, so air would be the way I would go.
On the nature of hamon formation these are my observations over the years. Contrary to what conventional wisdom may indicate, a successful hamon with positive sori hinges on the spine and body of the blade transforming well before the edge begins forming martensite. This sounds insane at first when one thinks of that edge exposed to the quenchant and the spine under the clay, but it is this fact that causes what I describe. By super-cooling through the pearlite range the edges transformation is delayed until around 450F, but the spine only needs to go to 1200F to lose its FCC austenite, and it can easily do this under the clay in water before the edge reaches Ms. In fact careful viewing of a successful sori formation reveals a downward curve before the subsequent reversal as the edge drops below Ms, indicating a BCC expansion in the spine beforehand- pearlite. If the quenchant is insufficient to cool the spine to pearlite first it will not act as an anchor for sori but will indeed be ductile austenite and move along with the edge expansion only to drop the tip when it converts to pearlite afterwards. Furthermore my metollogrphic examination of the habuchi area shows a lighter carbon depleted martensite bordered by carbon rich pearlite, indicating the area had lost its carbon to the pearlite formation first and the subsequent martensite got the leftovers. These conditions on the macroscopic scale seem to be responsible for much of the white borderline habuchi effect.
But while I dont see it in this thread, I do understand what you are saying about insightful people with plenty of experience, just moving on to greener pastures than many of the conversations on this forum these days. Oh, and as Thaddeus Venture himself would say have a scientastic day!
The most interesting thing about our craft is that you can ask the same question of six bladesmiths and still manage to get six entirely different answers, or explanations, and that is why just trying things for yourself may remain the only certain method of choosing your path. So now I guess I can add my entirely unique answer to the ones already presented. After working with the simplest carbon steels, oil hardening steels, even some air hardening steels, and having completed the circle by working with truly simple water hardening steels in the same forms as ancient and tamhagane steel, I have drawn some conclusions myself. Water works very well with traditional Japanese blades because they are not made from modern steels with alloying. Even the simplest 10XX contains manganese, which changes everything, and it is in all our modern steel. In light of this I personally have no use for water or brine in quenching any modern steel, but I have seen it work well with bloomery or tamahagane steel.
Before looking at the quenchant, in order to fully harden any steel proper austenite solution is necessary. This is the case with any steel, in order to achieve the initial BCT martensitic structure enough carbon has to be in the matrix for that transformation to occur, putting less than .6% to .7% into solution means you do not achieve full hardness. Now how fast you cool things determines how much of this carbon you got into solution stays in solution, but alloying slows that loss of solution allowing slower quenches, but it also increases distortion of the lattice when the hardening occurs. You will notice many recipes for water quenching modern alloys suggest much lower austenitizing temps in order to avoid blowing the steel apart. Lowering the soak temperatures lessens the amount of carbon in total solution and thus lowers the amount of distortion or cracking, this makes total sense when you realize that by not fully hardening the steel you lower these chances. With the simple iron/carbon ancient steels I have worked with there wasnt the same need to deprive the austenite, and subsequent martensite, of carbon and full hardness could be obtained in water without the same fear of self destruction. Simple, ancient steels = simple ancient quenches (water). Modern alloys were specifically designed to allow slower quenches with full hardness and less distortion and cracking, forcing them back into a more severe quench can only be accurately described as driving a square peg into a round hole.
With modern alloys most of the same activities and beautiful hamon features can be achieved with an oil specifically formulated for extreme speed, not any oil but an oil designed to harden modern shallow hardening steels. In know this because I have done it, and I know many smiths who have devoted the time to learn how to get these results with 10XX in fast oils. While the activity can be just as striking, the sori will not. This makes total sense when you reflect on what I have described in the paragraphs above. While full hardness can be achieved the distortion will not be as dramatic due to the gentler quenching action.
I am not a fan of water for anything but the simplest of iron/carbon steels, simpler than any steel commercially made today. I am also dead set against heating any oils except a carefully formulated, dedicated martempering oil. If one interrupts a quench, be it water or oil, the assumption must be made that it is for the purpose of drastically slowing the initial cooling rate, air is an excellent insulator, much better than water or oil, thus simply removing the blade from the quench at Ms is what I would do. If there was clay I also wouldnt want it fouling up my low temp salts, so air would be the way I would go.
On the nature of hamon formation these are my observations over the years. Contrary to what conventional wisdom may indicate, a successful hamon with positive sori hinges on the spine and body of the blade transforming well before the edge begins forming martensite. This sounds insane at first when one thinks of that edge exposed to the quenchant and the spine under the clay, but it is this fact that causes what I describe. By super-cooling through the pearlite range the edges transformation is delayed until around 450F, but the spine only needs to go to 1200F to lose its FCC austenite, and it can easily do this under the clay in water before the edge reaches Ms. In fact careful viewing of a successful sori formation reveals a downward curve before the subsequent reversal as the edge drops below Ms, indicating a BCC expansion in the spine beforehand- pearlite. If the quenchant is insufficient to cool the spine to pearlite first it will not act as an anchor for sori but will indeed be ductile austenite and move along with the edge expansion only to drop the tip when it converts to pearlite afterwards. Furthermore my metollogrphic examination of the habuchi area shows a lighter carbon depleted martensite bordered by carbon rich pearlite, indicating the area had lost its carbon to the pearlite formation first and the subsequent martensite got the leftovers. These conditions on the macroscopic scale seem to be responsible for much of the white borderline habuchi effect.
What is it about "super-cooling through the pearlite range" that delays the BCC expansion?
EDIT: ohhh, looking again at a 1084 TTT (for example), It looks like if you cool fast enough, you stay austenitic! Wow, that totally solves the whole "downward curve in oil, upward curve in water" dilemma that I couldn't quite reconcile to myself.