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01-08-2017, 11:39 PM
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Steel Addict
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Join Date: Oct 2016
Location: Columbus Ohio
Posts: 205
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I have a couple knives that will not sharpen like the rest. I just heat treated a small cleaver that is a replica of the first I made. The second gets really sharp but the first will not. After looking at the first under the microscope I think the grain size is too big due to the heat treat. The weird thing to me is that the second cleaver that gets sharp was heated a bit hotter than the first. Does the grain size get smaller up until the correct heat is reached and then start growing? I am just curious why the blade heated a lot less would have a larger grain.
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01-09-2017, 09:17 AM
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Founding Member / Moderator
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Join Date: Jun 2002
Location: Wauconda, WA
Posts: 9,840
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Over heated blades will have larger grain. I'm not metallurgist enough to explain the details but the bottom line is if you get the heat right (within a very narrow range) and then do the correct quench you end up with a grain structure that lets the blade perform to its potential. Anything outside that range may still seem to work OK but it will not be 'the best'. Well outside that range and you get a blade that will fail ...
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01-09-2017, 09:25 AM
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Steel Addict
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Join Date: Oct 2016
Location: Columbus Ohio
Posts: 205
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would it be possible that my steel needs to be normalized before the heat treat? If I break a piece of the 1084 straight from Aldos and look at the grain, should it be fine? Or if I under heat the steel, say only bring it up to non-magnetic. Should the grain still be fine since it has not been overheated?
Last edited by gkyle840; 01-09-2017 at 09:29 AM.
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01-09-2017, 11:17 AM
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Founding Member / Moderator
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Join Date: Jun 2002
Location: Wauconda, WA
Posts: 9,840
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One of the reasons, probably the main reason, we recommend starting with 1084 is that it is a very forgiving steel with regard to heat treating. Straight from Aldo you should not need to normalize and, straight from Aldo, I would think that the steel would tend to bend so much that breaking it would be difficult.
The only grain size that matters is what you have after the HT is finished. If you have to normalize to get a fine grain then do so, otherwise don't. Working out things like this, finding the correct temperature for the steel you have, getting the quench correct, through experimentation is what makes us knife makers. Make some coupons, do the tests, and find out what works with the steel you have. When you think you have it right, make a blade and do all the edge tests, cutting tests, and then break it to see if the grain matches your best coupon. If the knife performed the way you wanted it to and if the grain looked as good as your best coupon then you have your process. It would be very difficult for anyone to give you more specific instructions than that with any assurance that the instruction would really answer your questions because we don't have your steel, your heat source, your oil, and we can't really see what you see. Follow the process I outlined being as careful as you can to be consistent with each step and you should find your answers...
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Tags
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1084, bee, belt, blade, blades, buffer, carbon, case, edge, file, finish, forge, grind, hot, knife, knives, leather, made, make, man, material, sharp, sharpening, stainless, steel |
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