Will 0-1 benifit from Cryo

OK I'm glad it's not two words for one thing :)
I understood the concept of bainite and the why's but
not the wording of interrupted quench I missed something somewhere I guess I'm Cool now,,
 
Kevin,

Do you suggest to me a tool steel not go into temper before falling below about 125 F post quench?. Perhaps I misread your post I think. ... well I did go back and re read you and after stumbling through some terms I think I not understand it does seem you suggest TO allow tool steels cool below about 125 F before placing in temper. If I am wrong in my assumption please advise and correct me. If however that be the case I shall most respectfully disagree.

As a note of interest: my credit to Tim Zowada, even though eluded to total HT, was - for the purpose for Brian - the intrerrupted quench. I do not remember if or not Tim advised me about when to place into temper but without deference it is correct in my opinion.

RL
 
oh man do I have alot to learn...... ;)
When you say quench at 350 degrees do you mean lower the non magnetic steel to that temperature....let air cool ...then temper?
Sounds like magic :D voodoo stuff :D HE HE

I wonder if I get some temerature melting crayons I can learn this cooling time frame.

How would the results differ than what I am doing now? I understand thats a loaded question so...any info is fine ;)

This is good stuff.
 
rlinger said:
Funny Brian
Click to expand...

No I am serious. They make crayons that will melt at certain temperatures. If I quench and pull that blade out touching the 400 degree crayon and it doesnt melt then the blade is below 400 degrees. Does that make since?

I wasnt kidding Roger...this could be very cool since 0-1 is partially an airhardining steel anyay. Bet not many folks interupt there quenching.
 
Drawings would be better here but I'll try with words. Martempering/marquenching means to quench to just above the Ms temperature, hold it there until the blade is completely at that temperature then continue cooling [in air ] to room temperature. The "continue cooling " occurs before any bainite can form. This minimizes quenching stresses. The "interrupted quench" is for those who don't have molten salt to quench in. For that you have to quench in oil to just above the Ms ,then take it out of the oil [interrupting the quench] And let air cool. The diffuculty there is that it's hard to determine the blade temperature and the temperature may not be uniform throughout the blade.It will take a bit of experimenting to get it right. Either way , each steel has it's own Ms temperature .To quench to 350F means that you are measuring temperature to the flash point of the oil , ~350F, and you may in fact be dropping the blade to below the Ms but will still be reducing over all quenching stresses.Temper afterwards........My contention still is that if you have warping or cracking problems with a shape as simple as a blade it is more likely to be the result of decarburization or stresses from forging etc in the blade rather than just quenching stresses.
 
Mete or Kevin
why can't you quench in oil at 125 or so get it below the point of change(fast with this oil) to say at around 400-500 deg's then quickly remove it and stick it into pre heated oil at 350 deg's? and hold there..then snap temper :confused:

I would think that the 350 oil would (be just a put on hold for the blade to) keep it from dropping to low and a known temperature pre the immediate snap temper. :confused:
 
I think I see part of what he explains. The other, most parts, went right over my head and straight into outer space. I got some of it though - I think - and that is good - I guess.

RL
 
I've been following this thread with interest, since I posted a similar question on Swordforums a few days ago. If I understand correctly, marquenching works in salt because of the rapid thermal transfer, plus no flare-up, whereas if you quenched in oil heated to 400, you wouldn't cool the steel fast enough and would get significant flaming. I've also thought, like Dan, that you could quench in your usual oil (120 degrees or whatever), then pull it (ie interrupt the quench) and put the blade in like a deep fryer with oil already at 400, and slowly cool from there. The problem is how to know when the steel is at 400 degrees!

I've seen these hand held infrared thermometers advertised at Enco and some of the auto supply places which you aim at a surface and it gives you an instant temp reading. Maybe you could use something like this to check the temp of your blade as you pull it from the quench to make sure you are at about the martinsite forming temp, then either air cool or "oil cool" in a fryer - sort of a "modified marquench" . Kevin or Mete, does this seem do-able, or is it too far "out there"?

Bill
 
Dan , let me clarify - you quench into 125F oil until you drop temperature to 350F which you tell by when the oil flashes when you start lifting the blade out of the oil . Trying to quench into 400-500F oil presents two problems one of safety since the whole tank of oil can ignite, and the slower quench rate which may not get you past the pearlite nose fast enough........billf, the infrared thermometers might work but you might need another hand !! If you could set it up so you wouldn't have to hold the thermometer it would be better....It would be so much easier if you bought some tempering salts and did it right !
 
Mete

Thanks again for the help. Of course, you are right, it would be better to just go with a low temp salt set-up and marquench for real! It's just the inertia factor of changing over, getting the stuff, calibrating it etc that leads to these flights of fancy whereby we try to reinvent the wheel with our regular set-up!
Bill ;)
 
Roger descibed this process to me a couple of years ago and I've worked to achieve the desired temps. But it's all guessing for me, I have no temp control in my forge and limited oil temp control (beyond a single blade). I can say though that it makes a huge difference over the straightforward heat to critical quench till cool and temper approach. It's worth working for. The more I read about this the more convinced I am that I need salts.
 
mete said:
Dan , let me clarify - you quench into 125F oil until you drop temperature to 350F which you tell by when the oil flashes when you start lifting the blade out of the oil . Trying to quench into 400-500F oil presents two problems one of safety since the whole tank of oil can ignite, and the slower quench rate which may not get you past the pearlite nose fast enough........billf, the infrared thermometers might work but you might need another hand !! If you could set it up so you wouldn't have to hold the thermometer it would be better....It would be so much easier if you bought some tempering salts and did it right !
Click to expand...

I'm thinking the oil at or just above 350 you can have a bottle necked tank
then cover it once in the tank,, can't be more dangerous than starting up the salts Salt's

and the slower quench rate which may not get you past the pearlite nose fast
I'm not seeing that as a problem, because you'd be almost there from the
125 oil right? or even a warm brine % mixture to control the rate of decent?


I'm just looking for a way for the non salt guy to get the best they can without the dangers of salts and expense
or the reason it absolutely can't work.
 
Roger:

I am not challenging your method in any way, I am sincerely disturbed that I may have overlooked some critical information and your disagreement increases that anxiety. Trust me if it had been somebody stressing the advantages of quenching during the new moon, I would not have bothered to post. But when somebody of your understanding and experience is that emphatic about something, I take notice. So I am not suggesting anything at this time, but I am asking for information that I may not have on what the consequences are to allowing O1 to cool below 125F. before tempering. Your respectful disagreement will indeed rob my day of a little harmony ( I will survive;)), but the possibility of serious consequences, that I may not be aware of, will really bother me.
 
Dan Gray said:
...I'm just looking for a way for the non salt guy to get the best they can without the dangers of salts and expense
or the reason it absolutely can't work.
Click to expand...

The interrupted oil quench is the best way to go about the poor man's marquench/martemper. As I mentioned, I have the whole salt setup and still go this route with shallow hardening steels. For what it is worth, I have played with 400F. oils and didn't play for long, they scared me whole lot more that salts and gave lackluster results (remember that fine pearlite can act an awful lot like martensite, if you don't know it is there). If one had to go with the hot oil, they make marquenching oils designed to handle those temperatures.

Practice with the oil you are using and it is fairly easy to judge the interrupt temp. I like to see the oil coating the blade with just very light wisps of smoke. Put your gloves on and practice giving the steel a bend. If it bends real easy there is still a majority of austenite and you did all right on the temp., if it burns you even through the gloves you may have been too quick.

Tim Zowada is fond of telling guys new to it about the "ouch" test. When you interrupt the quench touch the blade with your fingers, if you pull your fingers away and they are all blistered and burned- IT WAS TOO HOT. If you can touch it for any ammount of time with comfort- it was too cold. But if you instantly whip your fingers away and say "OUCH", and that is about all- that is just about right! :D He's a nice guy but there is a bit of the sadist in him- you would be surprised how many people will actually adopt this method :confused:
 
I think there may be some confusion on the entire process here, I apologize for techy talk, you really can make good knives without $5 words, honest ;). Perhaps we shouldn’t assume that all reading this already have experience with, or are familiar with the concepts of marquenching.

First of all, much of industry calls it martempering, but I feel this is a gross misnomer and has lead many a new smith to believe that it eliminates the need for a follow up temper- WRONG. It all relies upon the fact that austenite (the internal state of steel at the high temperature) is only stable at those higher temperatures. The first temperature in the quench that it will want to transform into something else will be in the range from approx 1100-900F. where, if cooling is not fast enough, varying amounts of fine pearlite form. If you cool fast enough to avoid this, you will still have austenite. With continuous cooling the next transformation range will be from approx 500F and lower, you hold above this for extended periods for the bainite. This is marked by the “Ms” we keep mentioning, it is the martensite start point.

Stopping the cooling above Ms allows you to equalize the temp throughout before making the plunge into the highly stressful martensite transformation. The martensite transformation is classified as “athermal” which really makes little sense since it is the opposite of what that word would imply:confused: . What this means is that it is solely temperature dependant, with time having little effect. Cool until you get 50% martensite and then stop and you will not get any more martensite, no matter how long you wait, until cooling continues.

Since martensite is completely temperature dependant , by allowing the steels cross section to equalize in temperature, you can cause the martensite to form evenly throughout. Otherwise the thinner sections would transform sooner, expanding and tugging the other sections all over and possibly causing distortion.

One very nice benefit of this is that you can put on gloves and eyeball the blade as it is cooling, if you see any distortion occurring, you still have soft pliable austenite to in there to work with so you can gently and easily straighten it. If get doubters of this in my “Intro” class, I have them put gloves on and I stand over them as they heat treat their favorite blade. I tell them exactly when to pull it out of the oil and then I grab the blade with my gloves and let them see that it is still nice and straight. Then I will grab it and bend a good kink in it, hand it to them and tell them that they have about 3 minutes to straighten it :D . They are always believers after that. ;)

Of course the auto-tempering effect that I mentioned is the other benefit. The gains in impact strength can be pretty surprising. Another demo that I like to do with my class is to demonstrate the interrupted quench and when the blade has cooled, I hand it around for the class to look at, and file check that it is fully hard. Then with no subsequent tempering at all I hold it head high and drop it point first onto the concrete floor. It is not good for the floor but the tip always does fine. None of it is magic, nor even a secret, it is just using the materials and the processes in a way to take advantage of simple metallurgical principles. Industry has been doing it for decades.
 
"Industry has been doing it for decades." That's what I've been trying to tell you.! Blades are simple but when you deal with complex shapes marquenching becomes mandatory.
 
Hey Kevin,

If okay with you I think I'd like to take back the respectfully dissagree and replace it with: the reason I prescribe to that is because some published writings including some data sheets advise me to do it that way. There is no way I am able to talk the same language you and Mete do, so I will defer to your judgment on this and am happy to listen and even try what you can suggest to me. It is just that I have always tried to comply with the hand warm rule and my primary basis for that is technical writings. No, I am not able to explain scientifically why.

Roger
 
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