Tripple quench, once and for all. Maybe

Lynn i got my meter at Harbor Freight on sale for $19.99 (it is normally $39.99), it came with a type K themo couple and reads to 1000 degrees CELCIUS (celcius only). i have made me a chart with the conversions for the temps i have beeen told to shoot for. it is Item 37772, Cen-Tech Digial Multimeter, made in China. i mounted the themocouple in my forge out of the path of the flame so i could tell the temp inside.
 
The only times I do a triple quench is when I screw up the frist two :D
But, then, I'm still learning ad right now want to keep things simple.
 
mete said:
...Therefore they are treated to a spheroidize anneal condition where the carbides form spheres in a matrix of ferrite ( like chunky peanut butter)...
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Oh my gosh! This got by me the first time around :eek: ! mete used a colorful metaphor :D Have I finally corrupted him? OK to stay in proper form now I must say "mete, we don't get to choose between smooth or chunky when ordering from the mill" or perhaps "Choosy mothers choose O1";).
Hahahha, just messing with you mete- it's a good metaphor :D

I have said before that spheroidized material machines like butter- well not EXACTLY like butter, since it doesn't grease up your cutter and chuck, melt and throw slippery globs all over you. And locking it in the vice would just make a squishy mess ;)
 
Gotcha, Kevin ! As for time to spherodize I must admit to be at a lose. The books say " time and temperature dependant " well I already know that .It would depend on whether you are starting with martensite or pearlite and the amount of cold work if any.Recrystallization temperature of ferrite is 930 F. I would have to assume at 1200F it would take 2-4 hours to spheroidize......The recent posting about drilling steel - I wonder if the steel had a structure of pearlite instead of spheroidized ....pearlite in high carbon steel is very difficult to machine.
 
Since some of you seem to think that there is nothing to be gained by triple hardening cycles. Could you please explain to me what testing regimin you are using? I will agree that a rockwell hardness of 62-65 on the first quench should be as good or even better as the same hardness on subsequent quenches. But Most of the tests that I have done show that a triple quenched blade will cut longer and bend farther than a single quenched blade of the same steel. I have read posts that claim that near perfect control can be used and that this control lets the user achieve a near perfect quench so why should this person take a chance of screwing up this near perfectly hardend blade by reheating for subsequent quenching. I ask myself that; If this heat sorce is so precise and can be controlled to within +/- 5 degrees then how can there be any chance of over heating/ damaging or otherwise undoing what has accurred on the first quench? I have also read on these boards that people that use an O/A tourch for their heat sorce are not getting complete alloy solutions and that is why they see benefits to the triple quench. and last I read that the cutting of rope is not an accurate measure for performance on a given knife. That is why I am asking for more tests that I can do, and also why I did this test :

I took one piece of new L-6 steel and cut out two blades of the same size and shape. (6" boning knife).

I put these two pieces in my Paragone oven and programmed it for two two hour spherodizing heats at 1250 d. F. and just left it for the night.

The following day I removed the blades from the oven and cleaned up the scale from the spherodizing and prepared for hardening.

I heated my Paragon to 1550 d F., as out lined by Crucible, and put the blades in the oven. Crucible prescribes a soak of ten to thirty minutes for pieces up to 3 inches thick, so I gave the blades At .085, five minutes to staibalize and then a ten minute soak for a total of 15 minutes in the oven from room temp.

While the blades where heating/soaking I warmed my quenching oil (texaco quenchtex A) up to 165 d F. and let it stabilize there.

When the blades were ready to quench I removed then from the oven and fully quenched both. I did one in each hand so that they were both done at the same time.

After the oil had cooled to 140 d F. I removed the blades and put them on the bench to cool to room temp and then put them in the freezer for ten minutes and then into LN2 until it stopped bubbling and hissing then into sifted wood ashes out of my wood stove to warm back up to room temp. No the blades didn't crack and I did it this way because that is how I do it.

When the blades had reached room temp ( about twenty minutes) I put one of them in the evenheat for a two hour draw at 350 d. removed and let air cool and repeated twice more.The other I repeated the hardening process twice more and then tempered three times at 350 d F. two hours each cycle

I then ground sharpened and tested both blades. The tests that I used were;

To recheck for hardness using a new Nicholson black diamond file. The file just scated on both blades showing that they were at least 60 rhc.

The brass rod test, I do this by running the entire edge across the rod on both sides. Both edges flexed nicely but the single quenched blade chipped after the third flex, alternating sides and the triple quench made six flexes on each side with no chips. ( was the single quenched blade harder than the triple Maybe).

I then resharpened both blades making sure to remove the steel that may have been fatigued by the brass rod test and started cutting one lay from a 1 inch hemp rope. the single quench blade made 35 cuts on the rope before it started to slide and not cut. I used about the first four inches of the blade for this test. I resharpened and repeated the cutting for a total of five times. This blade averaged thirty seven cuts on this rope.

Next came the triple quenched blade. It was sharpened and cutting started. After 160 cuts this blade woulde still dry shave arm hair and showed no signs of wear, even under a 100x microscope. This was about as many cuts on the same same rope on the same day with one sharpening as the single quenched blade had taken five sharpenings to make. The triple quenched blade was still very sharp after making five times the cuts on one sharpening.

The next test was the nintey degree bend. I fully expected both blades to pass this test as they were both pretty thin stock. To my surprise the single quenched blade broke just before reaching nintey. The triple quenched blade bent to nintey and returned to fully straight I bent it back and forth to ninety dergrees four times and it is still in one piece and still shaving sharp.

I had put both blades in simple micarta handles and ground and sharpened both blades to as near the same as I am capable of. the single quenched blade was destroyed by the same tests as the triple quenched/tempered blade passed with ease. The triple treated blade went on to bone and cut up the hind quarter of an elk and break, bone and cut up an entire cow with out the need of further sharpening. During cutting up the cow it was steeled once. When I asked the butcher if it was getting dull, he said no it was still cutting well and that he had done it from habit. He also said that it seemed to cut better after steeling than it had imediately before. When he was done I took the knife and checked the edge it still felt sharp but would not shave hair. I borrowed his steel and steeled the edge of the knife. This brought the knife back to shaving sharp.


So after reading this long and to some ridiculous post. Please advise me as to what I could have possibley done wrong in My treatment of the single quenched blade. And also in My tests, why though appearing harder the single quenched blade failed where the triple quenched blade was unharmed. This is very interesting to me as I am trying to make the best performing blade that I can and if a single quench is better then why will it not do as well as a triple quenched blade in My testing?

What testing have any of you done that will invalidate the tests that I have done? I really want to know.

Bill Burke J.S.
 
Although I dont believe that an artist should allow science alone to decide where his work will lead, There actually should be the ability of the artist to support the results that he finds with some real science.


I have no idea why some knives just seem to us to cut better than others, I also just dont think that a cutting test done by hand is able to answer the questions we are asking that knife to answer.

Perhaps there is a better type of cutting test that does not rely so much on the arm of the individual who holds the knife?...A type of test where knife makers all over the world can test their own knives to the same standard in cutting ability?

I have made very few blades in my life compared to most of you, however I have kept track of the on-going conversation. And I did as I was advised,
I did what I was advised to do and test my own knives against each other.

So far I have not found the support for my triple quenching that I thought was there.

What I would like someone to tell me that supports my use of triple quenching is what changes?

Because I have been paying attention lately to the information put out by steel producers and by professionals who deal with heat-treatments of steel on a full time basis, and I have yet to read that the steel is scientifically proved to be altered after a 3rd quench compared to the same single quench.

I still normally end up doing 3 different quenches anyway, but this is because of the need to get one quench done correctly. So yes, I also would not doubt that my single quenched knives might well be inferior to the more practiced 3 quenched blade.
 
Excellent post, Bill. Do you use a scale to cut on in your rope cutting tests? I agree that simple rope cutting isn't the "end all" test of edge holding, but I do think that a rope cutting test can go a long way in telling whether the blade will hold a superior edge. Ed Fowler and Wayne Goddard did a comparison of triple quenched vs. single quenched blades, as well as forged vs. stock removal, several years ago. The test is detailed in Mr. Fowler's first book. I believe the steel was 5160.

Having seen the results of the Fowler/Goddard test, and now Bill Burke's test, is there a place where we can see results refuting their findings?

Todd
 
Bill,

Thanks for the excellent test and post.

I'm more in the triple doesn't matter camp - but still trying to prove it to myself. I always thought it had more to do with variance in using a torch or forge than anything else. I've always wondered if someone used an oven what the difference would be. So, your test is very appreciated.

Here's an attempt from a novice to explain the situation: You performed 2 spherodizing heats. So let's assume that your one-time blade went directly from spherodized to austenite to martensite. By third time you treated the other blade, it certainly wasn't coming from spherodized state!

In my 1084 post Kevin said:
A couple of heats at 1250F to 1325F will give you a very soft steel without the step 3 with 10XX steels. In 10xx steels above .80% carbon you will get spheroidal shaped carbide clusters. This makes for a very soft material but be aware that you will need to soak a little longer to pull that carbon back into solution when you heat treat. I often get phone calls from makers wondering what they did wrong with a hypereutectoid steel that has extra carbide forming elements. They get an odd damascus like pattern all over the blade. I tell them to soak longer or raise the temperature before the quench to dissolve those extra carbides and alloy banding and the problem will go away.
Click to expand...

Could that account for the difference? Now I'm wondering if you normalized prior to the final hardening, if you'd get the same positive effect.

Hmmmm....

Steve

(Given my limited knowledge I should probably keep my mouth shut, but I'm so interested in this topic I can't help asking to get my brain clarified.)
 
Sando....
When I heat the blade in the forge, then quench it in the oil, and as I take the blade out to look at it...The same thing always happens...

In the back of my mind there always is that doubt,,,"Is it good enough?"

"Am I done, or should I try that one more time?"
 
DaQo'tah Forge said:
Sando....
When I heat the blade in the forge, then quench it in the oil, and as I take the blade out to look at it...The same thing always happens...

In the back of my mind there always is that doubt,,,"Is it good enough?"

"Am I done, or should I try that one more time?"
Click to expand...

DaQo'tah, I'm with you bud! On top of that I wonder:

"Did I hit 1550 or 1650 degrees? That's going make a difference. Maybe the spine is 1500 and the edge is 1700?"

The pro's can do a dozen tests in a day and develop their skills. I'm lucky to make one test a week. That's why I'm so interested in switching to the oven.

Steve
 
Considering the hardenability of L6 it is suggested that it be annealed rather than normalized.I f so it should have come already spheroidized ???? If it is already spheroidized what you did was not only unnecessary but may have altered the structure to the point where a triple hardening corrects problems from your spheroidizing. Even without that why did you double spheroidize ?.....Does your quenchant have a recommended temperature of 165 F ? The recommended 140F comes from years of industrial experience where it was found that it provides the best combination of fluidity ,cooling etc.
 
I am editing this and other posts of mine here to clean up my act. I could have handled this whole thing a lot better than I did. I must apologize.


The three points that I should have conveyed with this post, without being so abrasive are:

1. Extraordinary claims, require extrordinary proof.
2. The burden of proof naturally, and logically, rests with the one making the claims.
3. Can anybody offer any possible explanations for the underlying metallurgical mechanisms or causes for the results being claimed?
 
mete does not live anywhere near me, we have never met in person, and we have had no private correspondence regarding this issue, yet I am confident that I know what his answers will be to the following-

mete, I have noticed that the triple quench idea seems to always work better with steels that have either hypereutectoid makeup or carbide influencing, alloying elements, (lower temperature operations also seem to be a common theme). How much of a difference would you predict it could make with 1084?

I will let you explain why (perhaps with some help from Sando, since he seems to be on the same track). ;)
 
I personally couldn't care less about the underlying metallurgy in any heat treat formula. I want to know what works the very best for a given steel. I don't care at all why it works. If someone could disprove the triple quench theory, then I will gladly stop doing it, because it would be proven to be a waste of time. My shop testing, admittedly unscientific, yields results that indicate triple quenching improves the performance of my blades. My interest in the matter is solely one of improving the performance of my knives. If anyone can prove with testing that triple quenching doesn't help, I'll gladly change, but I'm not going to change because metallurgical theory says I should. I want the tests to confirm the theory.

One reason that the tool industry might not be interested in triple quenching is the added time/cost factor. The way they are doing it is good enough, so why add more time and money to the equation?

Kevin, I respect your work and testing to the utmost. I know you are very busy with your own projects, but, if you ever find some extra time :) , a simple test conducted by you would go a long way towards convincing me my testing is flawed.

Todd
 
Todd,

(Here I go sticking my nose in again and I might be off base, but ....)

In order for Kevin to perform such a triple quench test, he would have to have a piece of steel from you in which you did everything prior to the first quenching and then he did the rest.

I'll just bet you that given enough time, testing and samples, that Kevin could re-produce your results with a single treatment AFTER he prepared the steel.

In otherwords, I think it is quite possible that the magic of the first 2 heat/quench cycles isn't in of themselves important, but rather what they do to the steel to prepare for the third. Therefore, it is also possible, that you could do something else to prepare the steel and get there with a single quench.

========================
For example, I just got back from a Hammer In. The ABS Master was explaining that in the 'old days' they did edge packing. People swore by it, and it produced a better blade.

The same guy that did it for years says that instead you should heat the blade just past non-magetic, then wave it in the air. Cycle it that way three times. They 'discovered' normalizing to reduce grain size.

I knew the story from before, but THEN IT HIT ME! Those edge packing guys were right all along - almost. They were convinced that edge packing reduced the grain size because of the light mashing they gave the steel. In reality they were normalizing with a quick heat. The pounding was a placebo. The lower level heating cycle was the actor.

=================================
So, between that last trip with the hammer and the final quench you have two other quenching cycles. It could very well be that a different process between that last forging session and the final quench could do the same thing.

Steve
 
Todd Robbins said:
I personally couldn't care less about the underlying metallurgy in any heat treat formula...
... I don't care at all why it works... Todd
Click to expand...

I am not sure what I can add to this, as it pretty much says it all. We just have profoundly different ways of looking at the world. I am simply saying that if somebody wants me to see the world their way, I do care about why it works.

I have the utmost respect for your right to treat you steel in any way you see fit. As for myself as long as I work with metals, all of my heat treat formulas are inseparable from the underlying metallurgy. I personally will go to my grave still trying to know more about how and why it all works.

A recipe is simple instructions on how to do the same thing again and again, be it the best or not. A complete understanding of the process and its underlying mechanisms allows one to vastly improve the process or write a whole new recipe.

But I do understand what you are saying, because even though I have not accumulated enough data to make definite statements about some of my materials and processes, I am sticking to them, due to what I have seen. I am just not going to make rash conclusions and possibly disseminate bad information to the public about it.

"It is always more important to question the answers than its is to answer the questions"
 
Sando said:
Todd,

(Here I go sticking my nose in again and I might be off base, but ....)

In order for Kevin to perform such a triple quench test, he would have to have a piece of steel from you in which you did everything prior to the first quenching and then he did the rest.

I'll just bet you that given enough time, testing and samples, that Kevin could re-produce your results with a single treatment AFTER he prepared the steel.

In otherwords, I think it is quite possible that the magic of the first 2 heat/quench cycles isn't in of themselves important, but rather what they do to the steel to prepare for the third. Therefore, it is also possible, that you could do something else to prepare the steel and get there with a single quench...

Steve
Click to expand...

Hey Sando, I think I like you more every time you post. You seem to really have a handle on this issue. As I said earlier in this thread, thermal treatments before hardening can have as much influence on the final product as the quench. I just prefer, for what I see as very good reasons, to do those treaments much earlier in the process and do the quench once, the best that I can.

I would love a private message with the name of that smith that explained the normalizing process in his demo, I think I like him a lot also ;)
 
An important point ,which I have stated many times ,is that the more complex the alloy (higher carbon and alloying elements) the more critical the times and temperatures. We recommend steels like 5160 and 1084 to beginners because they are simple to heat treat and forgiving. Yet we see these steels being triple normalized,hardened ,tempered ,and cryo'd !! What happened to the simple ?? In the eutectoid we go immediately from ferrite to austenite with iron carbide that is easy to dissolve.IN higher carbon steels we go from ferrite, to ferrite +austenite , to austenite (see iron -carbon diagram) requiring higher temperatures. In steels containing carbides of Vanadium and other types ,the carbides are more difficult to dissolve thus requiring more time in austenitizing.So if you are trying to do the higher carbon ,higher alloy steels and use the 1084 proceedures it's going to take three times!!! ......Asfar as science we always want to know exactly why --because only then can we do it the best way and reproduce (no matter who does it)the results every time.
 
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