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Heat Treating and Metallurgy Discussion of heat treatment and metallurgy in knife making. |
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#46
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I thought I would interject this into "water tempering" discussion. I thought this might be were it was going but was wrong. It may have been in Mr Carter's book, or videos, or somewhere else altogether. Anyway, this Japanese smith was using water to tell what temperature his blade was at while being tempered. He would sprinkle water on the hot blade, and depending on how the water "dances" or boils on the surface of the knife, he could fairly accurately gauge the tempering temperature. Pretty neat!
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#47
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Can someone please tell me is it realy neccesary to do cryo treatment on the forged blade?
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#48
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IMHO, it's never 'neccessary' to cryo a blade, forged or not.
__________________ Andy Garrett https://www.facebook.com/GarrettKnives?ref=hl Charter Member - Kansas Custom Knifemaker's Association www.kansasknives.org "Drawing your knife from its sheath and using it in the presence of others should be an event complete with oos, ahhs, and questions." |
#49
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Cryo treating only helps steels that are air hardening and have secondary hardening characteristics. It has little or no effect on simple carbon steels. Forging steels that can benefit from cryo shouldn't, and usually isn't to be forged by newbs. 5160 isn't a steel that would benefit from cryo.
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#50
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I think that cryo treatment is one of those things that someone sees someone else doing and decides that they should do it too.
The first problem is that they don't understand what is happening and don't realize that the someone else is using a very high alloy steel. Something that is rarely seen in forging. Or they are unable to understand that all the other person is doing is making his steel cold. which would be the case with 5160. Some of the very high carbon steel might be improved with cold treatment if the austinization temperature was not controlled and retained austiite was allowed to form but 5160 has too low of a carbon content to develop retained austinite. Doug __________________ If you're not making mistakes then you're not trying hard enough |
#51
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Agreed Doug.
Too often, cryo is something used to sell a knife, because buyers think it is some super high-tech, mystical process that renders the blade impervious to any and all abuse and allows it to hold a shaving edge after chopping granite into sand for decades. I can just hear Billy Mays' voice in his over-the-top 'shout-pitch' in a late-night infomercial about yet another 'wonder knife', talking up the magical properties imparted by cryo treating. Yes, cryo can make a small, but measurable difference in some blades, made of very particular steels, meant for extreme use. There is a place for that process in knifemaking world. I just don't occupy that space (even when I use those steels). Maybe some day. __________________ Andy Garrett https://www.facebook.com/GarrettKnives?ref=hl Charter Member - Kansas Custom Knifemaker's Association www.kansasknives.org "Drawing your knife from its sheath and using it in the presence of others should be an event complete with oos, ahhs, and questions." |
#52
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I need some informations about quenching the forged blade into oil. Does oil have to be cold?
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#53
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The oil needs to be approximately 120f. The warmer the oil (within reason), the lower the viscosity, so the faster it cools the steel.
__________________ A good friend told me one time about forging "What is there not to like, you get to break all the rules you were told as a kid, don't play with that it is sharp, don't play with fire, and don't beat on that" Wade Holloway See some of my work. |
#54
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Is this the same for water quenching?
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#55
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Water quenching as recommended by steel producers is actually a brine quench. Plain water is a violent quench, is less even in cooling, and slower in cooling, and is more prone to crack the steel. Brine cools faster, and much more evenly. I heat my brine to at least 100?, to 120?, but cannot say if it helps or not. A good brine mix is 13oz salt to one gallon of water. I use sea salt, or Kosher salt in mine.
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#56
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It should be noted, if you are using 5160 that is a forgiving steel. You can use Canola oil.
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#57
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Hey Andrew, i have found the book Step By Step Knifemaking by David Boye. In his book he explained the heat treatment for high carbon steels, will this tutorial work with every high carbon steels that i find?
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#58
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Ivance the simple answer is yes and no! Most simple high carbon steels will work by taking them to non magnetic and quenching in oil. But each steel we use has it's own "recipe" for a reason. Following the steps for the type of steel you're using will allow you to get the most out of your blade. Kevin Cashin has a lot of great info on his website and a google search of his name will bring up tons of heat treating info. He is, in my opinion, the heat treating god.
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#59
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Non-magnetic temp, 1414?, is not high enough, and not just any oil will do. Oils are not all equal in cooling speed. The steel needs to be between 1450? and 1475? for hypereutectic simple steels, but you can go a little higher for hypoeutectic steels, but seldom over 1500?/1525?. Canola oil has been tested to be the fastest of the vege oils, but proper commercial quench oils are the best, and gallon to gallon do not cost much more if any at all.
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#60
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Can someone please tell me what causes the micro fractures on the forged blade during the heat treatment?
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Tags |
5160, 550, blade, blades, dagger, edge, forge, forging, grinding, handle, heat, help., how to, kitchen knife, knife, knife making, knives, made, make, making, materials, micarta, mirror, post, steel |
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