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Heat Treating and Metallurgy Discussion of heat treatment and metallurgy in knife making. |
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#1
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Satanite use
I have some satanite and want to do some clay-back heat-treating of a 1095 blade.
Do I just mix the stuff with water until I get the desired consistency and pack it on? Do I need gloves or a respirator? What's the drill here? __________________ 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." |
#2
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whoa-boy, this can get complicated, but here's the rough and tumble and ping (that's the noise you hear when one cracks in the quench):
Wear a respirator when screwing around with the powdered satanite, otherwise you'll be breathing in finely powdered silica. After it's thoroughly mixed with water you don't need the mask anymore (obviously), but you might want to wear some latex gloves if your skin is sensitive to concrete (it'll definitely abrade and dry out your skin). Mix in enough water to make it about the consistency of a thick frosting. The goal is to make it sticky and easy to spread while not being runny. Application to the blade depends on blade length and thickness as well as your quenchant. If it's over 1/8" thick, you need a thin layer of clay on the portion you don't want to harden, say around 3/32 to 1/8" thick. If the blade is under 1/8" thick, you'll want a thicker coating, I recommend around 3/16". Don't go too thick or you'll get a heat-sink effect that will lower the hamon nearer to the edge. If you're quenching in oil, do not exceed 1/8" thick on the clay no matter the size of the blade. If quenching in oil, make the clay 1/4 higher than where you want the temperline to be, except for thin portions of the blade (i.e., the tip). Blades over 8 inches tend to take a reverse curve when quenched in oil. If quenching in water, coat the blade very close to where you want the outline of the hamon to be, maybe slightly higher to account for the heat-sink effect of the clay. You'll get positive curvature when quenching in water, even on small blades. Always make sure the clay is an even thickness and mass on both sides of the blade, otherwise you'll get warpage. Make sure the clay is put onto a clean blade, if one side pops off in the quench, you'll get warpage. Make sure the whole blade and all of the clay is up to temperature before you quench, or else you'll get warpage. Try soaking at the very bottom of the austenizing range (for 1095 I soak at 1425 F for around 5 minutes). This promotes thorough hardening and lessens the chance of cracking in a water quench. I let the clay harden overnight and then wrap the blade with a really thin wire, spacing the wrap around 1/2 apart. This keeps the clay on the blade when it hits the quench, and it also stops clay bits from floating around in your quench tank. Clay alone does not make a good hamon, most of the good stuff lies in the temperature you austenize at, the temperature of the quenchant, type of quenchant, how you move the blade through the quench. You can slap the satanite on the blade, scrape it off near the edge, and heat treat like you would for a through-hardened 1095 blade, but you'll get a boring hamon usually. Take your time, run some experiments with time,temp,and quench and you can control things and push the envelope for effect in the modern mill-run steels. |
#3
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Just remember, you are adding a very hot mass to your spine. In effect, you are creating somewhat of a thunderstorm in the blade, with that insulated, hot mass at the spine, and cooling mass at the edge meeting at the hamon when you quench.
My oven arrives TODAY woohoo, so i am really looking forward to controlled testing with hamons. Im interested in what can be done pushing the limits. I already have plans for a guard with a sprialing outward hamon....who says hamons are only beautiful on blades??? |
#4
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Quote:
The "thunderstorm" won't occur until the edge hit's 400F or so. A thin clay coat helps set up a nice springy mix of stuff above the hamon and into the flats/thicker areas of the blade (mix of pearlite, bainite, martensite--or what I expect is the make-up of 'utsuri'). Blades start cracking when martensite starts forming, the cracking becoming more probable if the back of the blade is still very ductile. If the back of the blade has cooled sufficiently to have the stiffer structures setting up as martensite is forming, it will fight the blades natural tendency to curve, thereby preventing the steel from tearing cracks into the edge. A good way to 'even' out the quench is to do an interrupted quench--in to the water for about 3 seconds, out for 3, in for 3, rinse,lather, repeat, temper immediately. All the above is for water quenching, oil is entirely different. You don't need a clay-coat at all to get hamon, and really cool ones at that. Just put on the ashi lines and edge quench in water. (rock the blade for about 2 seconds then quench the whole thing). You can also make them by using a higher austenizing temperature and leaving alot of meat in the spine/flats, especially with 1095. |
#5
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Thanks for the great tips guys! I'm gonna set-up the clay tonight and quench tommorow. I'll post results.
__________________ 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." |
#6
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I wish I would have paid attention to this the first time I read it. I'm one of those " It'll work " " Hold my beer and watch this " kind of guys , that has to try something before I'll ask or go loooking for help. Didn't heat all of the clay up , you got it , MAJOR WARPAGE. I shoulda used the oven. I wonder if I can straighten out that blade now ?
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#7
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Well, My grandsons (1yo and 4 weeks old) took all my attention these last two days. Man am I wiped out. Zero shop time for me. I'll get to it Thursday I hope. I may not make the deadline foe one of the three KITHs I'm in now. Oh well, this is great advice, and I don't imagine it's gonna go bad if I don't use it right away!
__________________ 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." |
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