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Main Boards => Hunting Knives and Crafters => Topic started by: kbaknife on December 17, 2009, 03:37:00 AM
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In another recent thread - Heat treat ovens - a question was raised about the TIME in getting the blade from the oven To the quench.
There is this misconception that this needs to be done in UNDER one second, or something like that.
Below is what I wrote on that thread, but thought it deserved its own thread so maybe those who didn't go there might see this one.
I hope it may as well, open up some dialogue that might allow for clearing up any other misconceptions, too.
"That facet of knife making is one of the most important, yet most misunderstood, parts of knife making there is.
This is why I and Lin repeatedly profess using the CORRECT quenching oil for knife making.
It's two in the morning here, so I hope this comes across right - it's NOT the time in getting TO the quench.
You could probably walk across the room if your blade is hot and thick enough. It'll hold the heat just fine.
The important factor is the SPEED of the OIL!!
To avoid what is called the PEARLITE NOSE, (which looks like a "nose" when drawn on a graph of time/temperature) once you have quenched the blade and the oil BEGINS extracting heat from the, say 1500 degree blade, the QUENCHANT needs to be able to extract the heat from the steel down to about 950-1000 degress in around 1 second!! But, of course, that is only for simple carbon steels like 1084/1095/W1/W2.
If the steel does NOT get below this temp, (950 in UNDER one second!) the steel will REVERT TO PEARLITE, and NOT make the transformation to MARTENSITE.
When using deep hardening steels like O1, L6, 5160 or 52100, because of the higher alloy content, this Pearlite nose is the same temperatures, but you will have about 4-5 seconds instead of one second to get the steel below 950.
So, you use a SLOWER oil!!
Get it? It's once the steel has BEGUN its radical downward decline in temperature, as a result of the quench, that it needs to CONTINUE in that direction to UNDER 950 in a few seconds, or it will revert to a condition OTHER than what you want.
It's the SPEED OF THE OIL not THE SPEED OF THE MAKER!
The relatively few degrees of temp you lose on the way from the heat source to the quench is UTTERLY IRRELEVANT.
I really hope a LOT of people on this forum read what I just wrote.
It was a really great question/topic and one that needed to be asked.
Maybe in the way it was asked, and in light of my answer, more guys will understand this basic aspect of making.
There is an EXTREME importance upon using the CORRECT QUENCHANT for the steel type being used. Goofy stuff like peanut oil and mineral oil and strange combinations of this and that, just do NOT have the correct additives to extract heat at the proper rate to avoid the Pearlite nose.
That's why so many new makers have such fits and failures in the beginning. Their oil doesn't get the heat out fast enough, and in all due honesty, the heat source itself is often insufficient as well. The combination of those two factors results in many, many failures and frustrations. In actual fact, the steel reverted to pearlite before the quenchant could get the heat out and FORCE the transformation to martensite.
Then, instead of blaming the heat and the oil, they blame TIME in getting to the quench as the problem.
Hardening a blade is a piece of cake if the maker will only be humble enough to admit he has an insufficient heat source and the wrong quenchant.
Good question!!"
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Excellent explaination Karl! Thanks bro!
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I'm awake now.
I didn't mention - for those that don't know - Pearlite is the unhardened condition of steel. That's the condition the steel is in before we place it in our forge.
When we bring it up to around 1500 it slowly goes into a condition called Austenite.
From Austenite, we want to force it into the condition of Martensite, which is an unnatural condition for steel and it would "prefer" to not go there as it is a hard and fragile and brittle condition.
If we don't get it below 950 in just a few seconds, it will go BACK to Pearlite.
Pearlite is its "happy" place.
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Thanks Karl. I once again have a better undestanding after reading one of your replies.
I have been using heated motor oil to quench my 01. As far as I know it gets hard cause a file dosnt bite at all. I am using color as an indicator and have quenched at a dark shade where I dont end up with a hardened product. Because I have worked up slowly through the color spectrum I dont believe the blade is getting to hot. Knives that i have broken on purpose have bent fairly far maybe 60 deg. and have a very creamy gray strycture. They also get extemely sharp!
I know the true test of a knife is usuing it for what it is intended for.
But in your opinion am I still missing some or the majority of what O1 has to offer by using these draconian techniques?
Thanks again for taking the time to post.
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How many times do we need to hear this? :D Well, maybe just one more time :readit: The single most important aspect of knife making!
You could probably walk across the room if your blade is hot and thick enough. It'll hold the heat just fine
One point to clarify on the above quote: while true of thick blades, thin or small blades won't hold the heat for very long and the quote above may just lead people to think, "well, I'll just get it a little hotter." That'll just cause it's own problems with the grain growth. Overheating something like 1095 and putting it in a fast quench medium is a recipe for a cracked blade as well.
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You are 100%, absolutely, without a doubt correct on all of the above.
I was joking - sort of.
On small blades, you can even move TOO FAST from the oven to the quench!
Fast lateral movement will COOL the blade off as you swing it through the air!
Don't want that.
Just be deliberate and direct and everything will be fine.
Thanks for pointing all of that out.
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Originally posted by farmboy:
Thanks Karl.
But in your opinion am I still missing some or the majority of what O1 has to offer by using these draconian techniques?
Yep - especially with O1. Lots of people use it mostly because of its availability. You can buy it everywhere.
But to get a good dispersal of carbides and all of the other alloys really dissolved and in solution prior to quench, O1 needs to soak at a controlled 1450-1500 for about 20 minutes.
Combine that with your choice of quenchant, and you are more than likely getting a combination of pearlite/martensite/banite/etc.
It'll skate a file with regularity, but you're not getting what you deserve.
With simple tools and equipment, you should match your efforts with SIMPLE STEEL!!
1075/1080/1084.
You might even ask me for some links and you could get some of the new Cry Forge V!!! Which is designed for the forging knife maker and is VERY heat treat friendly.
I spoke to the head metallurgist at Crucible Steel where this stuff is made, and asked him the hardening procedure.
He said, "Get it hot and quench it in something wet."!!
I use it and it's almost fool-proof.
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Originally posted by kbaknife:
Originally posted by farmboy:
Thanks Karl.
But in your opinion am I still missing some or the majority of what O1 has to offer by using these draconian techniques?
Yep - especially with O1. Lots of people use it mostly because of its availability. You can buy it everywhere.
But to get a good dispersal of carbides and all of the other alloys really dissolved and in solution prior to quench, O1 needs to soak at a controlled 1450-1500 for about 20 minutes.
Combine that with your choice of quenchant, and you are more than likely getting a combination of pearlite/martensite/banite/etc.
It'll skate a file with regularity, but you're not getting what you deserve.
With simple tools and equipment, you should match your efforts with SIMPLE STEEL!!
1075/1080/1084.
You might even ask me for some links and you could get some of the new Cru Forge V!!! Which is designed for the forging knife maker and is VERY heat treat friendly.
I spoke to the head metallurgist at Crucible Steel where this stuff is made, and asked him the hardening procedure.
He said, "Get it hot and quench it in something wet."!!
I use it and it's almost fool-proof. [/b]
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That's kind of strange up there!
I did a quick spelling edit and the "system" made an extra post?
Oh, well.
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"That's kind of strange up there!"
Hmmm... could be due to your lack of sleep... ;)
Great thread all!
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All right Karl,
Until I get a heat treat oven where can I get some cry forge V?
Thanks again i'll put my O1 away. But you are right it is easy to find!
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http://www.usaknifemaker.com/store/metals-forging-tools-steel-c-93_41.html?zenid=88299cbfafdec18e34df09c7eb78506b
On this page you will find both Cru Forge V and 1084FG - which stands for "fine grained" as it has a tad extra vanadium for grain size control.
Tracy Mickley is a great guy and many makers use him and support him.
Tell him Karl sent ya'!
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Great thread Karl,we all apreciate ,but you tell every one that using the proper quence oil is important and it is, but only part of making a good blade.Acually after seeing you do it in person the thermo cycle and the grind and the quence,even the drawback .
I don't think many people understand that every step has to be done perfectly to get a good blade.
Even if the thermo cycle is off on just one step (few degrees) the blade won't be correct.If the blade is not brought to temp evenly before quence it won't be correct and if the draw back is not correct it won't be a good blade.Its took a long time for me to understand .All I can say is everything is very imporant!!!
Why in the world are you staying up so late???
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Hardening a blade is a piece of cake if the maker will only be humble enough to admit he has an insufficient heat source and the wrong quenchant. (quote by Karl Anderson)
Karl, your statement about being humble struck me as noteworthy.
I have seen, even with myself, times when I was stubborn and wanted to force the steel to act in a way that was against it's nature. The maker has to be humble and recognize the limits of the steel as well as HIS OWN limits and tailor his methods accordingly. His methods dont have to be the same exact method as another maker. For instance, I may use coal as a heat source and another maker may use gas and even another may heat with an oven. Whatever heat source you use to heat the steel, learn to do it with CONTROL, being consistant from one blade to the next.
Other than that the next big factor is TIMING, which is almost the same as CONTROL. If you can CONTROL the TEMPERATURE and TIMING, you can do anything.
The quench is nothing more than getting the TEMPERATURE to a certain level, from a certain level, in the TIME that the particular steel requires.
The maker tells the steel to do something, but the steel tells the maker when it is willing to do it. Lin
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The maker tells the steel to do something, but the steel tells the maker when it is willing to do it. Lin [/QB]
Check this out, Lin, 5th from the top:
http://www.andersenforge.com/memorablequotes.html
I just had to do it!
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Originally posted by kbaknife:
The maker tells the steel to do something, but the steel tells the maker when it is willing to do it. Lin [/b]
Check this out, Lin, 5th from the top:
http://www.andersenforge.com/memorablequotes.html
I just had to do it!
You are right up there with Henry David Thoreau, Gen. George Patton and Mark Twain!
[/QB]
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Thanks Karl. I gotta keep it simple so I can undserstand it myself. :goldtooth: Lin
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mr. anderson sent you an e-mail.thanks
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mr. anderson sent you an e-mail.thanks
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Originally posted by Rooster1:
Great thread Karl,we all apreciate ,but you tell every one that using the proper quence oil is important and it is, but only part of making a good blade.Acually after seeing you do it in person the thermo cycle and the grind and the quence,even the drawback .
I don't think many people understand that every step has to be done perfectly to get a good blade.
Even if the thermo cycle is off on just one step (few degrees) the blade won't be correct.If the blade is not brought to temp evenly before quence it won't be correct and if the draw back is not correct it won't be a good blade.Its took a long time for me to understand .All I can say is everything is very imporant!!!
Why in the world are you staying up so late???
That's all good advice there as well.
I know this is basically a Bow Hunting web site, but this knife making sub-forum just keeps growing and growing.
I think that's really cool.
Eventually, many here will start to absorb information like Kevin just posted and we'll all start to see that there is MUCH MORE to properly heat treating steel than getting it hot and quenching it in WHATEVER.
ALL of the pre-heat treating steps set the steel up to be heat treated in the first place.
You can find yourself hardening an absolutely worthless piece of steel if you're not careful!
And you can ruin all of your hard work in a matter of a few seconds.
Just by simply not having control of your heat source and only having your steel too hot for a matter of seconds and you end up with a mess.
Forging, hardening, tempering, etc. is a PROCESS! and each step is effected by the previous steps.
Use the simplest of steels to begin with, take every opportunity to learn about the steps necessary for THAT steel and then move on to more complex processes and procedures.
It's a blast if you don't jump in too deep to begin with.
Kevin, I worked so hard yesterday I was in bed by about 8 o'clock. Then, I woke up about 2! I hate it when that happens.
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Mr. anderson, thank you very much for your advice and very quick reply.I dont post much but i feel compelled on his thread.i am NO expert...i have been forging about 5 years and took 1 bladesmithing class from herb derr.before the class i read many well known books on forging,hardening,tempering.i felt like it was somewhere between magic and rocket science.herb made me feel the opposite..."just do it ..it will be alright".not to suggest it is easy or to turn out an inferior product ...but to practice,test,forge and repeat.Don't freak out...just make a knife. sometime it is hard to find the balance ...as hard as to find the quenching temperature.but just do it and learn.thanks again for the expert advice. chad