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edge quenching any better than imersing the whole blade?
- Thread starter bldmkr
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- Jan 24, 2001
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Hi Ken,
Welcome to the forum! Edge quenching is better for most knives I think. It allows you to have a good hard edge but also a springy back that will absorb shock better than a fully quenched blade. Hope this answers your question.
HillbillyChuck
Welcome to the forum! Edge quenching is better for most knives I think. It allows you to have a good hard edge but also a springy back that will absorb shock better than a fully quenched blade. Hope this answers your question.
HillbillyChuck
im glad this thread came up, because i was wondering something about this.
by edge quenching, you get a hard edge but a SOFT back correct?
by quenching totally and then drawing back the spine w/a torch you get a hard edge and a SPRINGY back.
seems to me that a springy spine would be better, is it generally?
did i get that right?
by edge quenching, you get a hard edge but a SOFT back correct?
by quenching totally and then drawing back the spine w/a torch you get a hard edge and a SPRINGY back.
seems to me that a springy spine would be better, is it generally?
did i get that right?
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Like most things it depends on many variables. (Blade size, intended use, etc.) In general I'd say an edge quench is better than quenching the whole blade. On smaller knives though it probably isn't a big deal but you can make some cool "temper" lines.
Like Chuck already mentioned an edge quench allows you to have a hardened edge with a fine perlite spine. Makes for a tough knife, especially important in larger knives. A knife quenched in this method should bend 90 degrees instead of breaking completely, though the edge will probably crack. Much the same effect can be done by doing a full blade quench and then drawing back the spine with a torch. I prefer heating the entire blade and just quenching the edge. (Everytime I try the spine draw on a fully quenched blade, even if I keep the edge in water, I end up ruining the temper of the edge in some manner. I hate blue tips and edges!
)
Another take on the edge quench, of course, is the Japanese method of coating the blade with a thin clay mixture and then putting a thicker coat on the sides and spine of the blade and then quenching the entire blade. It's hard to argue with hundreds of years of continous bladesmithing refinement. I personally can't wait to try the clay coatings.
Yet another method would be to heat only the edge prior to the quench. This can usually only be accomplished by using an oxy/acetylene torch, though I imagine you could pass a blade back and forth in a coal or charcoal fire only heating the edge.
Sorry for the long post, I'm merely trying to illustrate the point that there are many methods of achieving much the same effect (hard edge, tough spine). An admirable quality in a knife crossing many times and cultures.
Oh and welcome to the forums! You won't find a nicer and more helpful group of folks than the knifemakers who frequent the online forums.
Like Chuck already mentioned an edge quench allows you to have a hardened edge with a fine perlite spine. Makes for a tough knife, especially important in larger knives. A knife quenched in this method should bend 90 degrees instead of breaking completely, though the edge will probably crack. Much the same effect can be done by doing a full blade quench and then drawing back the spine with a torch. I prefer heating the entire blade and just quenching the edge. (Everytime I try the spine draw on a fully quenched blade, even if I keep the edge in water, I end up ruining the temper of the edge in some manner. I hate blue tips and edges!
)Another take on the edge quench, of course, is the Japanese method of coating the blade with a thin clay mixture and then putting a thicker coat on the sides and spine of the blade and then quenching the entire blade. It's hard to argue with hundreds of years of continous bladesmithing refinement. I personally can't wait to try the clay coatings.
Yet another method would be to heat only the edge prior to the quench. This can usually only be accomplished by using an oxy/acetylene torch, though I imagine you could pass a blade back and forth in a coal or charcoal fire only heating the edge.
Sorry for the long post, I'm merely trying to illustrate the point that there are many methods of achieving much the same effect (hard edge, tough spine). An admirable quality in a knife crossing many times and cultures.
Oh and welcome to the forums! You won't find a nicer and more helpful group of folks than the knifemakers who frequent the online forums.
Although I have not edge quenched, from what I think I understand areas of metal that are not similar in temperature greatly increase the possibility of both warp and micro fracture when one area only is rapidly cooled. However, I wish someday to edge quench some too.
All my, few, blades have been fully quenched but not just because of the reasons above. It is because I am working non-tool steel high temp. stainless and the O1 (I love) was heated in a small forge.
Roger
All my, few, blades have been fully quenched but not just because of the reasons above. It is because I am working non-tool steel high temp. stainless and the O1 (I love) was heated in a small forge.
Roger
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Welcome to the world of knives and blade forums. The edge quench is a very dynamic method of hardening blades. The more of it you do, the more you will learn, providing you approach each and every blade with an experimental mind.
I have been asking a lot of questions about warp, investing with each blade. As a resault of lots of blades and reading as well as questions to our man in the laboratory, I believe that warp is a function of something happening to the steel at some point in time that was lacking in absolute bilateral symmetry. If we forge on one side more than the other, the steel will lack uniform grain from side to side. If we heat more on one side than the other, the steel will also differ. Some times one piece of steel will result is slight warpage no matter what we do to it.
We can reduce warpage by multiple normalizing heats, during and following the forging operation.
The guenching medium or method may reduce blade warp, but an inadequate quench to avoid warp may result in a blade that is less in performance quality, though possibly straight.
It is a simple matter to straighten a warped blade after tempering. Blades that manifest severe warp should be completed only with a lot of suspecion.
I have been asking a lot of questions about warp, investing with each blade. As a resault of lots of blades and reading as well as questions to our man in the laboratory, I believe that warp is a function of something happening to the steel at some point in time that was lacking in absolute bilateral symmetry. If we forge on one side more than the other, the steel will lack uniform grain from side to side. If we heat more on one side than the other, the steel will also differ. Some times one piece of steel will result is slight warpage no matter what we do to it.
We can reduce warpage by multiple normalizing heats, during and following the forging operation.
The guenching medium or method may reduce blade warp, but an inadequate quench to avoid warp may result in a blade that is less in performance quality, though possibly straight.
It is a simple matter to straighten a warped blade after tempering. Blades that manifest severe warp should be completed only with a lot of suspecion.
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The easiest is to place two pieces of wood on one vice jaw, as far apart as the length of the vice jaws will allow, one on the other. Place the blade in the vice two on one side, one on the other, the high side of the bend centered on the one piece of wood. tighten the vice and you can very precisely 'adjust' the blade to straight.
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This fall I attended the Ashokan seminars in NY. At one demo Tim Zowada first demonstrated ( using 01 steel) the effect of temperature on grain structure (very enlightening!) -This was a prelude to taking a forged 01 blade, full quenching it (Texaco Type A) and then drawing back the spine(spring center - soft back). This was done with a hand torch and the blade edge held over a pan of water. Tim has done this demo many times before - it produces a very tough blade. With other factors at play (edge geometry, steel thickness, etc) these blades, when place in a vise, are extremely difficult to bend 90 degrees much less going far enough to crack the edge.
This kind of method -performance really stirred up the question of what tests are valid/ what really makes a tough blade..... to date, I have been edge quenching and my testing has produced results I like. I'm going to try the spine draw back technique just so I can get an idea of the performance comparison. In the end, testing and, usage and the particular prupose for whic a blade is made will detremine what method I use.
Bob
This kind of method -performance really stirred up the question of what tests are valid/ what really makes a tough blade..... to date, I have been edge quenching and my testing has produced results I like. I'm going to try the spine draw back technique just so I can get an idea of the performance comparison. In the end, testing and, usage and the particular prupose for whic a blade is made will detremine what method I use.
Bob
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Great thread. Great to see Ed, one of the masters of this technique, on here.
One thing I might add it that the edge quench is not as simple as "hard edge, soft back." By adjusting the depth of the quench, and by selecting certain steels, you can precisely control the attributes of a given blade.
When preparing for my JS test, I made and tested and broke over 10 nearly identical blades (5160, 10" blade, 5" handle, triple normalized, triple annealed, triple edge quenched, triple tempered). The only difference was the depth of the quench. But what a Difference!
I finally decided to quench almost half way up my blade, and with steels like 5160, 52100, and L6 where you have a few seconds to drop from critical to below @900F, you will definitely get some hardening above the oil, and some transitional springiness above that. My point being, in a blade like this, there is nothing "soft" about the middle and spine. "Softer than the cutting edge" does not mean soft. I couldn't bend my test blade without a 3' cheater pipe, and after the 90 degree flex it returned to about 25 degrees with no set, just a curve through the whole thing. Not soft! (It was also a great pleasure and privelege to get Ed's and Bill's comments and advice on my blade!)
Some people say that edge quenched blades are "wimpy." They certainly can be, if you decide to quench only 1/8" of the edge. But you could also quench much deeper and wind up with a blade that is extremely strong and tough.
Oh, back to your original question, no need to edge quench 1095. In oil I have never gotten the spine to harden so I always get a de facto edge quench and visible hardening line.
John
One thing I might add it that the edge quench is not as simple as "hard edge, soft back." By adjusting the depth of the quench, and by selecting certain steels, you can precisely control the attributes of a given blade.
When preparing for my JS test, I made and tested and broke over 10 nearly identical blades (5160, 10" blade, 5" handle, triple normalized, triple annealed, triple edge quenched, triple tempered). The only difference was the depth of the quench. But what a Difference!
I finally decided to quench almost half way up my blade, and with steels like 5160, 52100, and L6 where you have a few seconds to drop from critical to below @900F, you will definitely get some hardening above the oil, and some transitional springiness above that. My point being, in a blade like this, there is nothing "soft" about the middle and spine. "Softer than the cutting edge" does not mean soft. I couldn't bend my test blade without a 3' cheater pipe, and after the 90 degree flex it returned to about 25 degrees with no set, just a curve through the whole thing. Not soft! (It was also a great pleasure and privelege to get Ed's and Bill's comments and advice on my blade!)
Some people say that edge quenched blades are "wimpy." They certainly can be, if you decide to quench only 1/8" of the edge. But you could also quench much deeper and wind up with a blade that is extremely strong and tough.
Oh, back to your original question, no need to edge quench 1095. In oil I have never gotten the spine to harden so I always get a de facto edge quench and visible hardening line.
John
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John - Good stuff. The variables in edge quenching are greater than one may think. If you were to do exactly the same thing with 10xx series steel (1084, 1095), I wonder what the difference in performance would be - (or how would you modify the process to get similar performance)
Bob
Bob
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- Jan 24, 2001
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Hey Y'all,
I do almost all of my knives(gettin' close to 50) so far with either 1095 or 1084 and I always edge quench my knives. It seems to work well for me, I've never had anyone say one of my knives was wimpy. I usually quench in preheated transmission fluid in a pan that is tilted so there is deeper fluid at one end than the other. When I set the knife in ands start rocking it the blade hardens along a curved diagonal line that starts at the top of the blade behind the tip and then curves along the blade and ends up somewhere in the middle of the blade/ricasso area below the tang(on a hidden tang). I heat the blade all the way in a propane forge. I've found that a very fast quench like tranny fluid or bacon grease will harden 1095 all the way through at the spine if fully quenched(and the bacon grease smells good too). I used to use Wayne Goddards goop recipe for quenching but with the bacon grease in there the mice would get into it and eat the crap out of it even with the tranny fluid in there, then I would have to go tearing around the yard after these half poisoned staggering mice so the dogs wouldn't get to them first. Also I had a big black snake that lived under my freezer that died from eating those poisoned mice. Now I just use tranny fluid and nothing seems inclined to eat it.
Chuck
I do almost all of my knives(gettin' close to 50) so far with either 1095 or 1084 and I always edge quench my knives. It seems to work well for me, I've never had anyone say one of my knives was wimpy. I usually quench in preheated transmission fluid in a pan that is tilted so there is deeper fluid at one end than the other. When I set the knife in ands start rocking it the blade hardens along a curved diagonal line that starts at the top of the blade behind the tip and then curves along the blade and ends up somewhere in the middle of the blade/ricasso area below the tang(on a hidden tang). I heat the blade all the way in a propane forge. I've found that a very fast quench like tranny fluid or bacon grease will harden 1095 all the way through at the spine if fully quenched(and the bacon grease smells good too). I used to use Wayne Goddards goop recipe for quenching but with the bacon grease in there the mice would get into it and eat the crap out of it even with the tranny fluid in there, then I would have to go tearing around the yard after these half poisoned staggering mice so the dogs wouldn't get to them first. Also I had a big black snake that lived under my freezer that died from eating those poisoned mice. Now I just use tranny fluid and nothing seems inclined to eat it.
Chuck
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Bob,
With 1084 the process would be fairly similar. Make and break a bunch of blades while playing with different depths of quench to try to get the optimum blend of hardness and toughness.
Some differences might be no annealing, only a triple normalizing, and much higher tempering temperatures (400-425 vs. 350), and MAYBE a single quench. I say maybe because, despite the fact that many claim no increased benefits with multiple quenching on 10xx steels, I still have to experiment more. Ed Fowler has discussed a possible decrease in the tempering temps. necessary to obtain a proper working hardness. I have independently confirmed this with 1095 (a triple quenched blade needed a temper of about 410F, while a single quenched blade took 425). More tests need to be done, but it's interesting.
I wouldn't use 1095 for a large blade. I'm using it now because I have a customer who specifically requested it on an order for a few smaller Japanese style pieces. A pronounced hamon and sharp edge are more important to the customer(s) than toughness, so.... 1095 produces a great hamon but it is difficult to control hardening and it is a bit more brittle than 1084 (though it is a perfectly good knife steel!). 1084 (usually, you have to get mill specs. for all your steel) has just a bit less carbon and more manganese, which make it easier to control in the hardening operation (wider/longer pearlite nose and deeper hardening, though still a shallow hardening steel).
John
With 1084 the process would be fairly similar. Make and break a bunch of blades while playing with different depths of quench to try to get the optimum blend of hardness and toughness.
Some differences might be no annealing, only a triple normalizing, and much higher tempering temperatures (400-425 vs. 350), and MAYBE a single quench. I say maybe because, despite the fact that many claim no increased benefits with multiple quenching on 10xx steels, I still have to experiment more. Ed Fowler has discussed a possible decrease in the tempering temps. necessary to obtain a proper working hardness. I have independently confirmed this with 1095 (a triple quenched blade needed a temper of about 410F, while a single quenched blade took 425). More tests need to be done, but it's interesting.
I wouldn't use 1095 for a large blade. I'm using it now because I have a customer who specifically requested it on an order for a few smaller Japanese style pieces. A pronounced hamon and sharp edge are more important to the customer(s) than toughness, so.... 1095 produces a great hamon but it is difficult to control hardening and it is a bit more brittle than 1084 (though it is a perfectly good knife steel!). 1084 (usually, you have to get mill specs. for all your steel) has just a bit less carbon and more manganese, which make it easier to control in the hardening operation (wider/longer pearlite nose and deeper hardening, though still a shallow hardening steel).
John
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Hey John,
Will you let us know the results of your experimentation with 1095 when you get done messing around with it? I am very interested to know the results.
Chuck
Will you let us know the results of your experimentation with 1095 when you get done messing around with it? I am very interested to know the results.
Chuck
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John: I sincerely apprecaite your experimenting and reporting your rsults. The variables we have to play with are unlimited. You are exactly correct when you stated the lowering of tempering temperature with the multiple quench. I have never seen it fail. The first quench results in a blade that appears harder and usually will read higher on Rockwell. It will require a higher tempering heat. By the third quench the blade will be softer on a Rockwell test, but cut longer and scratch a steel at 62 rockwell. There is a whole lot that happens with multiple quench.
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This is fantastic stuff!!!
How can steel read lower on Rockwell, but scratch a higher rockwell steel? That is amazing! I think I am going to have to get some different quench oils and do some slow quench/fast quench tests. Also I have never done multiple quenches on 1095 cause I thought that it wouldn't make a difference, but I see now that that is incorrect. Boy I got some serious testing to do! Thanks guys!!
Chuck
How can steel read lower on Rockwell, but scratch a higher rockwell steel? That is amazing! I think I am going to have to get some different quench oils and do some slow quench/fast quench tests. Also I have never done multiple quenches on 1095 cause I thought that it wouldn't make a difference, but I see now that that is incorrect. Boy I got some serious testing to do! Thanks guys!!
Chuck
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Another question here, y'all,
How are the quench oils different from each other? Like if I have that texaco type A which I think is a slow quench how is that different from say thick motor oil or bar and chain oil, which I think is also slow quench? Is it just the uniformity of the product or what? Inquiring minds are dying to know!!!
Chuck
How are the quench oils different from each other? Like if I have that texaco type A which I think is a slow quench how is that different from say thick motor oil or bar and chain oil, which I think is also slow quench? Is it just the uniformity of the product or what? Inquiring minds are dying to know!!!
Chuck
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Chuck - good question. I've been wondering the same. Not being able to find ( or someone who will ship) Chevron or Texaco quenching oil, I've been looking for alternative solutions. I used Brownells some, but understand it is a fast quench oil and maybe more appropriate for special steels. I used 30 w hydraulic oil (Non detergent oil) with 01 and got satifactory results -I had heard that this was the most similar to Tex and Chev quenching oil - appreciate any thoughts or illumuniation on this with regards to the steels that have been discussed -1084, 1095, 5160 , O1 & damascus (depends on steel mix?).
Bob
Bob