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Post by fullmetal56 on Dec 29, 2012 5:49:35 GMT
Ok so I have a couple of questions I really need answered. First up: Say I have an L6 sword, I heat treat it to get bainite to form, afterwards would it be possible to heat treat it a second time on just the edge to get martensite to form or would it not be possible for martensite to form at all on the second heat treat? Second question: is there a way to keep a certain part of a blade from heating up as much during heat treatment? For instance, I put a six inch layer of clay on either side of the edge of of a blade, would that keep the edge from reaching the temperature that the body of the blade would reach and if not then is there a way to achieve this at all?
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Post by stickem on Dec 29, 2012 13:24:10 GMT
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Post by LastGodslayer on Dec 29, 2012 23:14:39 GMT
I don't think there is any way to keep part of the blade from heating up. Metals, like Iron for instance, are good heat conductors, and for the size a blade usually has, It'll be in a pretty even temperature throughout regardless of being partially coated with an insulant. You could in theory either use induction heating or evaporate a volatile liquid as to keep a high differential in the heat gain/loss between parts of the blade.
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Post by fullmetal56 on Dec 29, 2012 23:56:25 GMT
This really helped but it didn't really answer my questions. It does mention that howard clark talked about creating an L6 blade with a bainite body with a martensite edge but it doesn't say whether or not he actually did it. I've read on other forums that he did in fact actually do it and it turned out great but they don't say how he did it, and I wouldn't exactly expect them to. Hence my questions, the second one has been answered, (thank you LastGodSlayer), but the first one remains open. But I thank you for your informative response.
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Post by LastGodslayer on Dec 30, 2012 0:16:52 GMT
When HC makes a L6 katana it has martensite in the edge (hamon area), but instead of the rest of the blade being mostly pearlite like in a normal katana, it is bainite. The steel alloy is L6, but that doesn't say a lot about the structure of the alloy. You can always normalize the blade and heat treat it again, but if you turn the entire blade into bainite, I don't think you can then turn just a portion of it into martensite. Maybe if you can cool the edge rapidly into low temp, but the easiest thing will be to do a normal quench of the normalized blade (from the ideal temp) turning the exposed area (hamon area) into martensite and then slowly reduce the temperature of the insulated area in some sort of special quenchant (I have no idea how though).
So basically, heat it up, dip it in water or oil, and then quickly put it in a very warm bath (hot enough for bainite to form) and keep it there and slowly cool it until you are left with just martensite on the edge and bainite everywhere else.
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Post by fullmetal56 on Dec 30, 2012 1:01:54 GMT
So basically do the edge first? (that's genius by the way, don't know why I didn't think of it ) But now my question is: If you do it that way, do you not risk the martensite changing into bainite or something else, or is it "locked" into that form?
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Post by stickem on Dec 30, 2012 1:38:16 GMT
Yes, I think most people would agree Howard Clark has done this. I am not certain how he does this, and haven't seen a "recipe" for the method online or anything. I have heard it is not the usual way of tempering with clay, so what you are looking for is not the "traditional" hamon-making process. Maybe this one can help you answer your ?s www.msm.cam.ac.uk/phase-trans/2004/z/3750-004.pdf
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Post by LastGodslayer on Dec 31, 2012 0:24:12 GMT
I guess there is a risk. Maybe it can be done in a single quench but that would require a precise control of the properties of the quenchant and of the coating - prolly how HC does it though...
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