Triple quench secrets to be revealed?(or not)

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guy's cryo is effected by time as much as temp. More time, less cold can get similar results to very cold and shorter times. Balance, as with so many things in metallurgy

What Jason said is true. The time had a lot to do with it....but...the edge holding and cutting ability of a knife is a combo of a lot of factors. Most small but added together they make a big difference. That's what "Custom Knifemaking" is all about. One of the knifemakers that I respect the most, told me one time that he found the knives he made in the winter when it was really cold, took a better edge. After that I have frozen them every way I can think of.

I have no idea why but it makes a small difference in the edge. Some things just can't be explained. Some things shouldn't be explained.

No one knows why fiddleback maple has some of the properties it has. So what! It has those properties and I am not going to start trying to explain why God makes some things happen. They just do! I accept iy and take advantage of it.
 
Peter, what are some of the properties of fiddleback maple you refer to other than its beauty? Not to start yet another discussion here but I do love the looks of that wood. Never used it.

Thanks,
Dave
 
It's getting confusing dozens of guys with dozens of inputs. Burke - the test you refered to is the Jominy end quench hardenability test, Jominy test for short. D.Forge - you really have to learn some basic metallurgy before you get into these discussions. You must learn and understand all the heat treating terminology otherwise things will just get too confusing. rlinger - I know you didn't mention freezing , I just wanted to clarify the heat treatment. Let me clarfy more , soak means at temperature ( lets use 1475 for 5160) . If you mean as time to include the time to reach 1475F that is not correct. That is why I mentioned that you would have to tell by eye the point at which the sample reached 1475. I know that adds a variable but without a research lab we have to live with it. ddavelarsen - Hard maple makes an excellent knife handle, I've made a few which I carved . Fiddleback is nice but when working it remember the grain changes direction and use sharp chisels. Birds eye maple is even fancier but even harder to work as the eyes keep wanting to pop out !
 
Yes, I was refering to any and all time periods you thought important to specify (ramp and soak). I won't know the cross-section until it arrives or until Bill tells us.
 
As someone deeply interested in this subject, and plans to use 5160 in a future knife project this has been a great thread.

My one question on these proposed 5160 tests is when you forge the round bar down to flat you are going to experience carbon loss from the forging. Will the carbon loss be enough to adversly affect the test? I have some hot rolled 5160 I would be glad to send but it is quite thick, about .300 thick.

On the stuff in the freezer raising the Rockwell hardness. I used to do this and see the hardness raise a point or so overnight using ATS-34. Then I just let it sit overnight at room temp and experienced the same thing.... ????

Great stuff guys.
 
Rob,

Yes, just letting it sit can sometimes do that. Just depends on the condition of the steel. Plainly speaking, the retained austenite wants to transform. Time v temp occurs in many extremes.

As for 5160, the only real carbon loss will be through decarb on the surface. This is usually ground away, along with any scale formed, once any stock removal takes place prior to final HT. You'll still have "good" 5160 underneathe. After that, as long as all dimensions and previous microstructures are the same, so should be the results of HT. :cool:
 
Jason, thanks.

Since I started press quenching everything I havent seen the rockwell raise after time, so it confirmed my suspicions that my quench wasnt fast enough on the air cooled alloys.
 
I agree, you hit it right on the head there Rob. On a side note, I've really been wanting to move into press quenching to avoid some slight warpage I get every now and then. Sounds fun too! :cool:
 
I just came in from forging the barstock down. The test pieces should be close to 1/8 inch thick. I brought them down to 3/16 on the hammer and I plan on gringing them down on the surface grinder to clean them up. I don't plan on taking them to exactly .125. Just cleaning them up to fresh steel and making them uniform. I did all the forging just above and below critical and then normalized. They are in the forge right now cooling down. Just in case anyone is interested All four pieces were heated to above critical (check with a magnet) and then allowed to cool to room temp In still air, (twenty minutes). After this time I could pick up the pieces with bare hand. The forge shut off and the samples put back inside for an anealing. This is all I will do to the three sample that Roger is going to get. The remaining piece will get two more anealing heats then be ground to the thickness of the other three. Then I will harden only half of it using the same procedure as I would if I were making a knife. The sample will then be polished and etched and sent to Roger for him to do the testing that he will do to all the others.
 
Bill,,,sounds great!...Im very Very interested in what we find going on in this test case,,

,say Bill, is there any way to keep the guy doing the testing a bit in the dark as to what sample was heat treated in each way?...give it some thought for it might help to not tell too much about each sample
 
To my mind the freezing has not much to do now in this experiment. Ed was speaking, if I recall correctly, the triple quenching and in a separate context about freezing.

The freezing not used in the big documented test, correct me if I am wrong.

To my knowledge freezing temperature to help clearly must be much lower than in standard home freezer (In Celcius degrees home freezer is minus 35 Celcius (mostly only -20), a maximum really much helping temperature is minus 75 Celsius). The reason to help is to get rid of remain austenite, coooret me if I am wrong (not being ametallurgist). Nitrogen liquid is something minus 190 Celsius, I do not know exactly. The freezing has normally done in this kind tanks.

Even I was joking about "Finnish outdoors frozen" knifes, the truth is, that we occasionally have minus 35 Celsius AND HEAVY WIND, it is perhaps this case freezing helps outdoors. But usually if the outdoor temperature is very low there is no wind at all (thank God!).
The possibility to use outdoor freezing properly is more theoretical.
Lowest temeratures measured ever (Siberia, south pole), are something -80 Celsius, you can move your forge there to avoid using freezing tanks and save money.

To be more accurate to avoid misunderstandings. Mete was earlier speaking about air hardening steels. Of course, I am not speaking about hardening and how cold air effects in air hardening but low alloy steels as 5160 and 52100 and fzeezing after hardening.

pig
 
Pig,

Maybe Roger can help us to find out if freezing has an effect on the steel. After Roger hardens and breaks the steel, maybe he can take the broken off piece of steel and put it in the freezer overnight and retest the hardness the following day? If one piece of the steel is not frozen as a control piece, and both are retested the following day we will have a better understanding if freezing (in the home freezer) affects hardness. The only question that I have is... What if the overnight freeze has more to do with the performance of the steel than just raising the hardness level? Could it be helping to further refine the grain structure or something else?

Given that Roger has limited instruments for testing, lets try to come up with some tests that Roger can do like this freezer test. That is, if Roger is willing.

Rick
 
Hello participants!


I did understand that some actual testing panned with 5160.
Could you, please, send some info to this thread what are your actual activities now. Or have you forgetting the matter?

What about my opinion to follow Ed Fowler's test (Blade magazine spring 1991) closely as cutting rope not only metallurgical lab studies (useful basically to metallurgists)?

Also what about freezing (discussed a lot), Ed was not using it in this test?



pig
 
Pig , it's getting very complicated . If we wanted to look at all the variables it would have to be done by a knife and/or steel company. Lets just stick to the original question - is there any benefit to triple quench of 5160 or will a single quench do the same thing ?
 
Mete, indeed!
Just for this reason I suggested "the one and only possible solution": let's repeat exactly step by step Ed Fowler's well documented and published test procedure but with only ONE CHANGE "single quench soak time test" against "triple quench no soak time". Ed did "single quench" against "triple quench", with no soak time both
(but in addition stock removals comparison with hammered, not needed now, and double quench comparison, not needed now).


pig
 
Rodger,

Steel is on the way. I sent it USPS priority so you should maybee get it by the weekend. Cross section is .155 as I measure it but them little marks on my ruller are maybee need calibrated. I surfaced them and then cleaned up the stone marks with a 120 grit belt. I left them thicker so you have room to do what ever you think may be needed if anything. I removed plenty of material after forging so there should be no decarberized steel left.
 
Mete and Pig,

I think it's great that you want to stick to the original question regarding the triple quench. But for the life of me I can't figure why you wouldn't want to see if leaving the blade in the home freezer overnight has any influence on the steel. Roger has everything necessary for this test. I'm assuming that he has a freezer at home to chill the beer mugs;)

It's not every day that we as a group get this kind of opportunity to learn.

I say lets get everything we can from Bill's 5160 donation and Roger's offer to do the testing. Of course, Roger would still need to agree to the freezer test.

Rick
 
I have one of those and a dewar for approx. -320 F. freezing. I will do as mete directs, but yes I can deep cryo as well as the household freezer method.

RL
 
Rick,
it was just as you said "I am sticking the original question" (and at a same time I admit also the imoprtance of other questions too). I am a kind of making a priority from only my own point of view, I am sorry it is looking as ignorant to other questions! It was not meant to be.

Also I admit that I have no deep knowledge (everything from books) or experience with freezing. Very much the same, unfortunately, as with the triple quenching. I was suggesting the test not because I do know better something but to get useful new evidence.


Let me continue a little bit my "one-eyed" talk.
Why?
Nobody commenting the importance of very similar test with Ed Fowler.
Please, comment!

We can:
(1) Invent our own different test
(2) Follow Ed Fowler test closely

If we take option (1), and both methods give similar results, then we can have for example following comments:

(a) They did annealing and tempering differently but Ed Fowler's method is "a whole packet", results would be different in an exactly same test.

(b) They tested the performance with HRC- test. HRC is not the only factor in the practical cutting (as a rope cutting test). Also HRC very well can depend on annealing, ...... done as Ed Fowler did.

Even we can have different opinions and comments to this kind arguments, it is even better not to make these possible.



pig
 
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