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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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Best RC hardness ?
I am shortly going to try some heat treatment-- I would like y`alls opinion as to what you consider the best RC hardness for your blade blanks and why.Also a few pointers would be appreciated.
Thanks in advance. Pred __________________ Be not afraid of the dark , be afraid of what hunts in the dark |
#2
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Are you going to be HT'ing with a torch or in a forge or furnace? Are you doing stainless or plain high carbon or alloy steels? Desirable hardness varies dependant on these choices and the intended purpose.
Please clarify these specifics and which specific steels you are interested in and advise/opinions can be offered. |
#3
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Sorry--I sometimes think too broad-- I need to narrow my thoughts down.
I will be wanting to heat treat Cable twist Damascus , 01 steel and possibly 1084 and 15n20 mix. I`ll probably be using a torch until I can afford a furnace. Thanks __________________ Be not afraid of the dark , be afraid of what hunts in the dark |
#4
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No problem, we can answer you now!
Because there isn't really a totally consistent carbon content in welded cable or pattern welded steel, Rockwell hardnesses vary all over the blade, and are less pertinent than in a blade with just one steel. For O-1, I like a hardness around 59 for a small cutter, or even 60 or 61 if it's not going to be used for anything that could snap it. For a prybar user, I'd suggest as low as 55-57, though edge retention will be diminished. There is an odd-seeming phenomenon, also, that forged blades seem to operate well at lower hardnesses than stock removal blades. As for heat treating with a torch, you may be best suited to search on "differential" or differential hardening" or "edge quenching" and research that methodology, as it is well suited to a torch. You can gain some insight in the tutorials, then perhaps we could flesh it out for you: http://www.knifenetwork.com/workshop/index.shtml Hope this helps a small bit. |
#5
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To give you a corner stone to build upon, generally think in terms of higher hardness giving greater wear resistance and lower hardness giving higher toughness. The trick, or objective for us knifemakers, is to find the hardness best suited for the knife application. Different steels provide different choices in hardness versus toughness. Some are very tough while being very hard. Some are not so. Study data sheets supplied by steel vendors. Many are available online at no cost.
RL |
#6
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This may be a stupid question, but .. "Do you have a RC measuring machine?"
If so, can I borrow it?? If not, and you're not sending you work out to be heat treated, then exact RC is of little importance. Yes you should have an idea of what you should be shooting for, but if you don't have a way of checking the RC, then why bother. Just be sure to test the blade after every step in the heat treating. And ALWAYS test each blade before it leaves the shop. I feel RC is of little importance if you can not measure it. So you should rely 100% on your testing to insure you produce a quality blade. |
#7
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Quote:
__________________ Chuck Burrows Hand Crafted Leather & Frontier Knives dba Wild Rose Trading Co Durango, CO chuck@wrtcleather.com www.wrtcleather.com The beautiful sheaths created for storing the knife elevate the knife one step higher. It celebrates the knife it houses. |
#8
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Arrrrgrggg Chuck,
I can't believe you brought up "edge packing". The only thing that generates longer threads than that is "triple quenching." Steve |
#9
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Hey somebodies got to stir the pot now and again....
__________________ Chuck Burrows Hand Crafted Leather & Frontier Knives dba Wild Rose Trading Co Durango, CO chuck@wrtcleather.com www.wrtcleather.com The beautiful sheaths created for storing the knife elevate the knife one step higher. It celebrates the knife it houses. |
#10
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You may be able to refine the grain size by forging, which should improve performance at lower hardnesses, but you can't get those atoms to fit closer together by forging. Sorry, not buying it.
__________________ Stay Sharp, RJ Martin Knifemaker www.rjmartinknives.com |
#11
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I tend to agree that exact Rc hardness is irrelevant. The key is to achieve a balance that makes the blade hold it's edge, be durable, and easy to sharpen. This can be accomplished easily with the brass rod test. Over the years I've asked many customers what their expectations are in a blade. First is edge retention, but right on the same level is ease of sharpening. Those can be two factors that are tricky to achieve with some steels. I have also found that customers who demand a specific Rc hardness are more often than not very inexperienced with knives, and are making that demand based on something someone else told them. Taking the time to experiment with your process to achieve a blade that will have the characteristics of edge retention, durability, and ease of shaprening will give you the confidence needed to refute those who taunt exact Rc harndess as the only measure of a blade.
__________________ WWW.CAFFREYKNIVES.NET Caffreyknives@gmail.com "Every CHOICE has a CONSEQUENCE, and all your CONSEQUENCES are a result of your CHOICES." |
#12
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Rc Hardness
Ed, I'm with you on the hardness issue. D2, with very high carbon and chromium content will hold an edge better than 5160 of the same Rc hardness because of the massive chromium carbides that form in the D2. Those Chromium Carbides are harder than woodpecker lips!
__________________ Which is worse; ignorance or apathy? Who knows? Who cares? |
#13
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Man those metallurgists do use some unique terminology!
Woodpecker lips? __________________ God bless Texas! Now let's secede!! |
#14
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Hardness....
...harder than $9 worth of jawbreakers and sharper than a widows tongue..... yep, my kind of knife........
__________________ Which is worse; ignorance or apathy? Who knows? Who cares? |
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blade, forge, forging, knife, knives |
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