Triple Quench for O-1......?????

Hello everyone. I find myself constantly trying to research heat treat methods. The otherday I read that with 52100 it is advisable to triple quench....it came with a long explanation that made sense to me. I use 0-1. I dont have a HT oven so I find it hard to soak at a paticular tempature and a particular amount of time. With that said i havnt read anything that suggest you do the same with 0-1. How do I get the best out of my O-1 using my small forge???????
 
Hello everyone. I find myself constantly trying to research heat treat methods. The otherday I read that with 52100 it is advisable to triple quench....it came with a long explanation that made sense to me. I use 0-1. I dont have a HT oven so I find it hard to soak at a paticular tempature and a particular amount of time. With that said i havnt read anything that suggest you do the same with 0-1. How do I get the best out of my O-1 using my small forge???????

sunny, if you would like to e-mail me, I would be very interested in hearing the details of any fresh explanation that could possibly make sense of triple quenching, but mostly I would be happy to discuss heat treating options for O-1 with you. kevin@cashenblades.com
 
Sunny, Kevin is a good man to correspond with, especially with dealing with O-1. I will give you my take on triple quenching just about any blade steel, just be aware that some people swear by it and some swear at it. You cannot do a quench without the risk of cracking the steel and the more aggressive the quenchant the more likely it is to happen. Cracking can be anything from the complete breaking of the blade to microscopic cracks, some so small that you would need an electron microscope to see. Also, the more carbon that there is in the steel the more likely cracking can occur because of the formation of plate martensite. It's formation also increases with carbon content to where around 1% carbon plate martensite will make up 100% of the martensite formed.

Now some claim that triple quenching is capable of refining the grain more due to the rapid cooling, with each of the three quenches progressively refining the grain. Some will allow that that could be true but triple normalizations, which puts less stress into the steel, followed by one quenching will do the same thing without as much risk of cracking. We, yes I am one who holds this position, feel that three quenches is three times the opportunity for cracking and may build up microscopic cracks that could lead to eventual blade failure. The vast majority of us, on both sides of the argument, do not have the capability of examining this on the microscopic level. This leaves some saying that the worry about microscopic cracking is overblown and that they have not seen anything to suggest that it's a real problem, just theoretical. The other side holds that, because we can't do testing to prove whether or not it is a real problem in our real world production, it's better to err on the side of caution.

Doug
 
There's a lot of conjecture and speculation on the multiple quench, going many different directions. Personally, I believe in it, not simply by doing it for a number of years, but through spectrograph testing of many, many samples. BUT! Here is the caveat.....

Based on the testing I've had done on numerous samples, everything points to it being effective on steels that posses .060-5.0% chromium. I chose to focus on 5160 and 52100 and how the multiple quench relates to/effects those steels. I've not used O1 in a long time, but did send a few multiple quenched samples in for testings. Looking at those results, although the steel showed a slight grain improvement between one quench and two, at 3 quenches the grain in O1 was essentially right back to what it was with a single quench. The one thing that caused me to stop chasing multiple quenches on O1 was the fact that differentially hardening it was hit-n-miss at best, and the ability to control the depth of hardening was a major aspect in my pursuing multiple quenching.

5160 and 52100 results showed improvement up through 3X quenches, then started to go the other way. Even with those two steels there are a lot of nuances that can "make or break" it.....it's much more complicated then just bringing the blade up to it's recommended critical temp and quenching. Variations occur with the austinizing heat you utilize, it's duration, and of course the quenchant used. Deriving the maximum benefit from multiple quenching takes a lot of time, effort, and experimentation.

I suspect there will be a number who will read this post and shout "hogwash!".....and that's OK. I achieved my JS, my MS, and have a number of cutting competition 1st place finishes under my belt utilizing multiple quench techniques that I have learned and honed over the years. I don't set back and say "that's good enough" either......I continually seek to better control, and improve results utilizing multiple quench techniques. Do I use it on everything? Of course not. Generally only on the two steel types I mentioned, simply because those are the ones that I know benefit from it versus a full single quench on the same steels.

As with most everything in knifemaking, it's impossible to provide "empirical evidence" that something "works" or doesn't. Were we in a perfect world, where there were no variables from shop to shop, and maker to maker, it MIGHT be possible.... and in SOME instances we can "get close", but after being in this game for all the years that I have, the one constant is that there are as many ways to do something, as there are people doing it. Only through a lot of time and experimentation do people gain enough knowledge/experience to be confident/comfortable with their results. I say that because over the last few years, it seems that everybody is seeking that "magic bullet"......wanting it "right now", and being unwilling to take the time and effort required to "learn".
Over the years I've had many "discussions" with many makers about multiple quenches....some receptive to it, others not. In most cases it boils down to a matter of opinion, and the tenacity to seek improvement each day you walk into the shop.
 
Ed does bring up one thing. Regardless of which technique that is used to refine the grain, that technique has to be done correctly. Just triple quenching or triple normalization is no guarantee that you will refine the grain. Grain growth, and refinement, depends on time and temperature. If you soak the blade too long at too high a temperature for the steel that you are using you will grow, not refine, the grain. As Ed alluded, you must know the steel that you are using. Something like 52100 will not give you the same results treated like 1080 or even 5160.

Personally, I would love to do a side by side study of the two methods with a variety of steels, including electron microscopy, but that is something that would run into the thousands of dollars. Money that I don't have.

Doug
 
The objectives I seek in a knife are tough and cut as well as lateral strength.

Every knife maker has what he needs to test these variables in his shop.

A steel bar to test the edge for chip

Something to cut, I use hemp rope and buy it by the roll to provide consistency. Always compare results to your reference blade. This can be a Richtig, or what ever old knife you have that cuts well and you don't mind sharpening it a lot.

A vice and a torque wrench to evaluate lateral strength.

A little microscope from Radio Shack taught me that all steel are not equal, even tough the claimed chemistry is the same.

Steels vary in quality, the microscope can many times let you see why a blade broke on the test for lateral strength. (even the best pour of steel will have an occlusion or inclusion once in a while).

I recently had a blade blow a chip out on its second 180 degree flex, the reason? An occlusion. This is the first time this has happened with one of my blades in Years.

Luckily I had a back up blade for the test and it did 14 180 degree flexes before the edge cracked. This blade made 700 cuts on my hemp rope before I quit cutting, it would have made more. It was a 4 1/2 inch blade and required over 40 ft. lbs of force for each flex until the bottom third of the blade hardened portion tore, this blade could have been straightened and used as knife again. A break is through grain boundaries, a tear is around them. The finer the grain the better edge flex, cut and lateral strength.

The most significant question you can ask a maker who gives you advice is: How do you test your blades?

Testing blade performance is the most significant effort a maker can do to learn his craft.

Let the science evaluate why.
 
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Ed,

I would love to see you put one of the knives you test on video. It would really show us in real time what you do.
 
I don't know if I am supposed to post this on this form, but if not will not mind the moderators pulling it.

We have a set of DVD's for $50.00 + $5.00 shipping.
or the 52100 DVD for $20.00. Don't have the technical ability to do the simple stuff. The last DVD has all the "secrets in it". From rate of reduction to the finished blade being tested to destruction.

Kevin Gray, a Graduate of the South Dakota School of Mining Metallurgical Engineering has written a technical report that will be published soon in a technical journal. Or you can read most of it is back issues of Blade, all in simple language that the average 7th grader can understand.
 
I don't know if I am supposed to post this on this form, but if not will not mind the moderators pulling it...


My understanding of the sales rule is that you have a limited number of freebies in a year. This would be a site wide rule so Bossdog could easily correct me, but I am willing to let it stay here in this instance, simply as a gesture of goodwill to preclude any notions of selective heavy handedness on my part. I just ask that we do not confuse the Heat Treating forum with the Classifieds section of Knifedog, I prefer advice over advertising.
 
Some forums have rules about directing questions to individuals, so hopefully this isn't one of them.

My question is for Mr. Caffrey. What results do you get from the spectrographic testing that make you a believer in triple quenching?
 
Good to see you here Ed. :)

I really don't work with 52100 much. Ed has more experience with it and triple quenching than anyone else I know. It's good to hear from folks that have the experience,... Ed and Ed. :)
 
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What is the Triple Quenching Process?

I asked this a while back. I got several replies, but nothing that explained it very well. So since the subject has come up again, I'm gonna try one more time :)

What is the triple quenching and or the triple quenching process?

Obviously I know what quenching is, but do you bring the blade up to the proper heat for hardening (let's say 1475 degrees for this example) and then quench, bring the blade back up to 1475 and quench again then bring it back up to 1475 degrees and quench for the third time OR...

are the people who are talking about "triple quenching" talking about quenching after each tempering heat cycle for a total of 3 cycles? OR...

Is it bringing it up to normalizing temp, quench...bring it back to normalizing temp and quench again then bring it back up to normalizing temp and quench for the third time?

This has always been a subject that intrigues me and I liked to know more about it.
 
When people talk about triple quenching they are talking about austinizing and quenching the blade three times. The first two times you are not concerned with getting the carbon into solution as much as causing a phase change so you only have to soak long enough to make sure the steel is heated all the way through. The third time you are concerned with getting the carbon into solution in the austinite you soak the third time as required by the steel that you are using. After the third quench you would proceed onto tempering. You would also normalize the steel before you did the triple quench.

Doug
 
I think there are several variations to the "triple quench", but since I don't practice it on a regular basis, maybe someone else will chime in.

Ed Fowler was the first bladesmith I know of to use and develop it, but since then it seems to have been modified and adapted to different types of heat treating facilities and equipment, various types of steels etc. Not everybody calls it “triple quenching”. However, it all has a couple things in common,… multiple quenching for grain refinement and the number 3. I’ve heard of essentially the same thing referred to as, I believe “thermal packing”, "cycle hardening" and just generically as "a type of thermal cycling".
 
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... and *I'm* hardly a moderator either - but I have purchased Ed's videos and watched (what may have been another 52100 blade) go through 180 degree flexes and crack on the 15th flex (by my count) - that was after this blade cut the hemp rope around 150 times. I don't think he's blowing smoke, folks. I've got 3 pages of notes from the 2 DVDs and I will be following up with my own shop tests to see how much of his experience I can incorporate into my work.

Now this looked like a soft back draw, not a spring steel draw... and on a stocky outdoorsman's blade geometry. Something you'd rely on in survival situations, not something you'd want to use to julienne potatoes or win a Blade Magazine beauty contest.

~ Michael
 
Thank you, we have been working on the High Endurance Performance Knife for over 34 years, invested over $70,000 in actual testing and Metallurgical Laboratory work. We did it because we wanted to so it was not a sacrifice but a long term quest that still continues. We knew good times and naturally many frustrations. There are no secrets or copyrights, so enjoy your journey. If I can answer any questions just email me or call.
 
Fred, pardon me for speaking for Kevin. I don't mean to be presumptuous but this is an offer that he's made to the general knife making public. Kevin is a very approachable person and he's responded to me on more than one occasion. He's frequently invited us to correspond with him.

Doug
 
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