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Author Topic: Hardeing Temperatures, how hot and how long?  (Read 1104 times)
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Ed Fowler
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« on: November 19, 2015, 07:19:17 PM »

Last winter I started a little experiment seeking to determine (again for me) how hot a blade needs to be inorder to harden for cutting performance.

I had six experimental blades all were quenched three times in three days and placed in the freezer overnight: All were brought up to temp using my Oxy Acet torch and then quenched, there was no soak times at the temp.

Two were heated a little above non magnetic and quenched in Texaco type A oil preheated to 165 f.
Two were heated to non magnetic and quenched as close to critical temp as I could maintain.
Two were heated to just barely magnetic and quenched.

All six were tempered at 388 f. in my paragon at the same time.

All passed the edge flex.

The blades that were quenched while still barely non magnetic were what I consider poor performers on the rope cutting test, only making around 100 cuts before the edge was gone. I then heated them to non magnetic and quenched, they cut very well.

Today I had two of the blades left to test. One heated to just non magnetic and the other heated just above non magnetic then tempered as usual.

I finished the blades and compared them for edge flex, they both passed, 4 edge flexes on each side and no chips.

Cutting performance was equal as far as I went, 700 cuts on the rope and still going.
Etching revealed a what I consider nicer pattern on the blade that was just taken to non magnetic.
Rex is too busy to check for retained austenite so I will just have to go with performance qualities.

I believe I reported similar results when I tested the the other blades.

Some claim that 52100 needs to be held above critical for a soak in order to harden. I believe these blades indicate that the higher temperatures and soak time is not necessary.

Years ago I tried the longer soak times and found that much of the wootz like pattern I like to see was gone.

Any comments are welcome.

     

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John Silveira
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« Reply #1 on: November 19, 2015, 10:25:26 PM »

Humm - that's interesting stuff -

i don't know what i was thinking when i quenched some W2 a short while ago. When i heated it i watched as the edge got to color i consider just past non mag. But i didn't let the whole blade come up to that color. I still don't have a Oxy Acetyl kit to edge heat blades. Never the less the blade didn't harden correctly to my satisfaction- of course being W2 i had clayed the blade going for a hamon line ( the hamon didn't form ) Tells me the blade that didn't have any clay on it didn't harden so the edge didn't harden obviously. Sanded the blade / re-clayed it this time making sure the whole blade was up to temp ( instead of just the edge ) and had a successful hardening and hamon !! This problem happened once before with W2 but i was being neglectful and repeated my mistake.

I realize you were talking about 52100 Ed and not W2. So i'll just say i have never soaked 52100 - i've made a few blades of the steel. With those blades of 52100 i put the blades into the forge holding them in my tongs with the edge into the flame basically heating up the edge. I don't have the control you do using your Oxy Kit so my blades of 52100 usually have the whole blade up to heat ( Non Mag )( i wait for the whole blade to change color) but again i don't do any "Minutes" of soak time like lots of guys claim. At the most i'll go one minute after i feel the whole blade has come up to Non Mag just to make sure the steel has really transitioned to the non mag state. Can't recall a time i've ever had 52100 fail to harden with that technique.

I've done a couple multiple quenches and was happy doing so with the above process. All was well. I haven't tried rolling the edges yet ( Brass rod testing ) but have gotten favorable results with cutting rope - 400 plus cuts which i'm ok with - and that's been on knives that were quenched one time.

Here's 52100 edge quenched once and was a good cutter.


i have noticed with my process of heat treating i've had inconsistent results with achieving the wootz grain patterns. Sometimes getting very little patterning.

below 52100 edge quenched showing more pattern ( this one hammered from a 1" diameter bearing ) if you look close you can see the second quench line - it's vague but about halfway up from the edge and extends through the plunge cut a ways into the ricasso


bad photo but this is the way it looked right after quenching


the blade above was one of my favorites i wasn't thrilled to deliver - it went to the person who gets me tons of 52100 at no cost. so i made the blade for him.

Same blade but the other side

i don't know why this side of the blade had grain formations that were much LONGER drawn out - was that from forging and drawing length into the billet ?


not much grain activity on the one above. don't know why .

Man i sure like the looks of that grain in the upper chunk - think it was quenched 4 times -


for comparison - this is actually Wootz steel i bought from someone.


don't have much more to say except " Man i'm such a rookie " !!

thnx - the quest continues















« Last Edit: November 19, 2015, 10:35:01 PM by John Silveira » Logged
Ed Fowler
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« Reply #2 on: November 20, 2015, 11:10:19 AM »

I really like that second photo, when forging a blade the memory of every hammer blow is revealed. Sometimes when etching blades from ball bearings wondrous events are recorded, all we have to do is figure where it came from.

Below is a multiple quench blade from a 6" round bar. The complex structure we can see is maintained throughout the internal structure of the blade, all we can see in the image is a mirror of what lies inside of the blade.



Recording it in a photo is another challenge, but you can get an idea from this photo. The soft area is a little high, but this blade is only 3/4 of an inch high.

« Last Edit: November 20, 2015, 11:36:01 AM by Ed Fowler » Logged

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« Reply #3 on: November 20, 2015, 05:33:24 PM »

Ed - so you agree the long drawn out grain pattern is the result of the metal being lengthened and drawn out ?  I know hammer blows but the 1" bearing was drawn out to over 6 inches in length - it must be that drawing "Length" that forms those long grain patterns visible after etching ?

that's always just been my hunch .

I am always trying to become a better "Listener" to what the steels are telling me..  For example : i've not been able to get what's called "Ashi" when working with W2. Through trial and error i started getting more and now i'm at the point i actually believe i know how to achieve more and even have some control over the patterns themselves. It had to do with a close to specific thickness of the clay applied where one wants ashi lines to form. Anyway not to get off topic....

Point is i've wondered how those grain banding lines have actually formed and as you said " all you have to do is figure out where it came from " LOL

You've got some pretty long drawn out grain structures in the photo you posted - Alot of meat up at the front of that blade - i like it ! Giving me ideas
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« Reply #4 on: November 20, 2015, 08:31:16 PM »

I am guessing that the swirl you see in your blade is from the original grain structure in the ball bearing. That is why I used to spend many hours trying to figure the direction of the grain in the balls before I started forging them. I finally decided that based on performance it was not worth the time I was investing. It was a real thrill to try to read them.

There is a lot more in that blade that I could not get to show up. It is a reverse taper modified price grind that I really enjoyed working up. You have a pretty good eye to notice the extra meat in the front third of the blade.

W-2, I worked with it for a while and could not come close to the performance I wanted and finally found out that what I was using was not W-2 and quality control was  not what I wanted. I have no idea what you are working with, but wish you luck.

Looking at that 'Wootz' steel you have reminds me of some stuff a couple of guys were trying to sell at Blade Show years ago, I asked them what it was and they said it was a "SECRET". I did not discuss it with them after than comment. If I could find a piece of it I would ask Rex to put his microscope to work and come up with his thoughts.

I have 7 blades in the Paragon now and will be working them up in the near future and plan on working on my photography to see if I can't get great photos like you are getting.

Somewhere I have a very expensive book on the old Wootz blades, looked for it today and can't find it. It had some fabulous patterns in it.
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« Reply #5 on: November 21, 2015, 10:41:36 AM »

Related article on Wootz- I have noted Al Pendray selling wootz knives many years at Blade. They didn't cost an arm and a leg, about $200-400 on ave.. from what I recall.
Incidentally, he was critical when I spoke to him of the methods Ed employs, but I couldn't keep up to understand where the real differences and problems he was convinced of regarding heat treating theory.  Maybe it was the "not by the book approach" he took issue with.. He seemed to know his metallurgy, hearing him talk for about an hour.

http://www.tms.org/pubs/journals/jom/9809/verhoeven-9809.html

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« Reply #6 on: November 21, 2015, 06:27:25 PM »

I tried a lot of variables while working up the multiple quench process, some of them worked some did not. I freely shared what I was doing and now 25 years later am still learning. At first I was working with ball bearings and they introduced many variables I tried to account for and many times was wrong. Much of this work was before Rex joined us in our work.  Seems like when I was wrong folks really remembered what I said.

It was not without some trepidation that I wrote the first articles about multiple quench. I talked to Darryl Meyer who did a lot of experimenting on his own as well as research in the public library, I asked him what he thought and he said sure it can work, why not? His statement gave me the courage to start writing about what I was doing.

One of my inspirations was a quote from the Kennedy campaign: "Behold the turtle, he only makes progress when he stick his neck out!"  I really stuck my neck out and am thankful that some have been working with the methods we worked up.

Rex found an extensive write up about Wootz that was the result of work done by some Russian students of metallurgy at a university. Their work was done in the 1950's and very closely paralled  what Verhoven and Pendary wrote up.

Their work and mine were nothing new, just better steel to start with for me. I do remember that after I started writing about multiple quench and 52100 Al Pendary started selling 52100 round stock so I believe they were working with it applying what they learned from their work with Wootz.

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John Silveira
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« Reply #7 on: November 21, 2015, 08:37:19 PM »

I am guessing that the swirl you see in your blade is from the original grain structure in the ball bearing. That is why I used to spend many hours trying to figure the direction of the grain in the balls before I started forging them. I finally decided that based on performance it was not worth the time I was investing. It was a real thrill to try to read them.

There is a lot more in that blade that I could not get to show up. It is a reverse taper modified price grind that I really enjoyed working up. You have a pretty good eye to notice the extra meat in the front third of the blade.

W-2, I worked with it for a while and could not come close to the performance I wanted and finally found out that what I was using was not W-2 and quality control was  not what I wanted. I have no idea what you are working with, but wish you luck.

Looking at that 'Wootz' steel you have reminds me of some stuff a couple of guys were trying to sell at Blade Show years ago, I asked them what it was and they said it was a "SECRET". I did not discuss it with them after than comment. If I could find a piece of it I would ask Rex to put his microscope to work and come up with his thoughts.

I have 7 blades in the Paragon now and will be working them up in the near future and plan on working on my photography to see if I can't get great photos like you are getting.

Somewhere I have a very expensive book on the old Wootz blades, looked for it today and can't find it. It had some fabulous patterns in it.

Ed - i believe those photos i took when my Sony F-717 was still working - the memory card went out and i've yet to get another - now using my I-Phone which i feel to be inferior ( surprisingly ).   if you Ebay Sony F-717 you will see plenty - some under 100 Bucks - just read the description so it includes everything needed and make sure it's a working model.

My friend who is a Pro photographer recommended i get one of them - great little camera that auto focus takes amazing photos - even up close shots.
good luck
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« Reply #8 on: November 24, 2015, 11:43:09 PM »

I really like that second photo, when forging a blade the memory of every hammer blow is revealed. Sometimes when etching blades from ball bearings wondrous events are recorded, all we have to do is figure where it came from.

Below is a multiple quench blade from a 6" round bar. The complex structure we can see is maintained throughout the internal structure of the blade, all we can see in the image is a mirror of what lies inside of the blade.



Recording it in a photo is another challenge, but you can get an idea from this photo. The soft area is a little high, but this blade is only 3/4 of an inch high.




Hey Ed - regarding that reverse taper on the blade you have posted here - did you get a chance to use it much - am wondering how you liked the performance of that grind .
I'm thinking that drawing i recently submitted of " Popeye " the blade i'll be making soon it may be a good candidate for me to do a reverse taper on since it looks like it would have a fairly fine tip . The reverse taper would strengthen that tip .

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« Reply #9 on: December 01, 2015, 06:31:29 PM »

Related article on Wootz- I have noted Al Pendray selling wootz knives many years at Blade. They didn't cost an arm and a leg, about $200-400 on ave.. from what I recall.
Incidentally, he was critical when I spoke to him of the methods Ed employs, but I couldn't keep up to understand where the real differences and problems he was convinced of regarding heat treating theory.  Maybe it was the "not by the book approach" he took issue with.. He seemed to know his metallurgy, hearing him talk for about an hour.

http://www.tms.org/pubs/journals/jom/9809/verhoeven-9809.html




Pretty elaborate article .

was surprised not to see Kevin Cashen's name there among the credits. whatever !
 
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