Triple quench secrets to be revealed?(or not)

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?? intesting it's at the top of 16 on my browzer:(

here it is by Kevin

Originally posted by Kevin R. Cashen

Kevin R. Cashen
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Registered: Sep 2003
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Posts: 37
I don't want to start a stink but I would like to share some knowledge that I have came across and has proved true in all of my experience.

The phenomenon of patterning that survives heating has been mentioned and this was confusing to me also, until I accessed information that was probably gathered in a lab under what I would call "controlled" conditions. I must admit that I am a control freak and detest unknowns and rampant variables.

In steel that has carbide forming elements, repeatedly heating in lower temperature ranges (below Acm) will cause the carbides to segregate out into sheets or networks which will become very visible and have a "wootzy" or patterned appearence. You can even press all kinds of designs into this and it will take the impression in the patterning, very well. It is the concept behind the Wadsworth-Sherby technique for making "Wootz" that was considered before Pendray nailed it. Wadsworth and Sherby were two very scientific guys working in labs that knew what was going on in there and how to get it to happen.

This can be done with many steels and is easier with hypereutectoid (above .84%C) O1 and 52100 work good, I have heard that some "S" series respond very well to it also. I have even seen some folks who have dishonestly passed it off as wootz on unsuspecting people and this is why I wanted to point it out.

I did this one day just playing around with an old 52100 bearing race to prove a point. I heated it up and got things into solution and then lowered the temp below Acm and kept it there long enough for the carbides to segregate. I then dented my initials into the surface and forged it flat. The results was a very patterned piece of steel with a big "KC" showing right in the internal structure of the piece. I even heat treated it while keeping the images intact. I posted it over on Sword Forum and let people guess what the heck it was. It would have stayed there as long as I stayed in a temperature range that didn't mess with the carbides. But I could have erased it entirely, simply by heating in excess of Acm and holding it there long enough to pull it all back into solution. It is also worth mentioning that the same thing can be done with real wootz, heat it hot enough and long enough and you will erase the pattern made my those undisolved carbides.
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RL, I still have the samples that I fractured. If you or others would like to do further work speak up. I don't know what else you could do except metallographic work for grain sized.BTW insufficient soak would be difficult or impossible to determine through a microscope.
 
Mete,

As I said in my post above I would like to send them to the lab and have a full analisis[sp] done. send me an e-mail and I'll give you my address.
 
Good Morning!

In the shop early this morning this thread kept spinning around in my head. More questions than answers at this point.

Since I am not a scientist it seems important to put it in simple terms. Let me see if I can "nutshell" this thing.

One side of the discussion practices the single quench method. They work steel at a technically prescribed forging range. Their process is to normalize at or over critical(non-magnetic), then heat treat using soak times according to specs, and then quench.This side would say that during normalizing, the steel loses it's previous stressed condition becoming a blank slate.This side would say that during the soak time prior to quench, the steel is refined further, and when quenched, achieves maximum benefit from one effort. This group feels there is little or no increase in perfromance due to repeated processes such as the multi-quench. They believe the added processes are too time consuming and impractical. This side uses smaller barstock as provided from a mill. (Is this accurate for the most part?)

The second group practices a series of thermal/mechincal processes which begins with forging. This side forges at lower temps than the single quench group. This group practices a different normalizing process( Bladesmith Normalizing ). It also use an annealing sequence (Sub Critical) as part of thermal treatment. This side uses the edge quench in Texaco Type "A" quench oil. This side uses a repetitive hardening cycle which involves a 24 hour wait between each quench. This side uses cold as well as heat during the thermal cycles. The multi-quench group believes the repeated processes enhance the performance characteristics of the steel. This group believes in using larger barstock which has to be reduced to blade size.
(Ok guys check me for accuracy!)

It would seem the disagreement happens when we discuss the idea of "memory" in the steel. In point of fact, it has been explained that if steel is subjected to mechanical manipulation, and then treated in a specific manner it will indeed remember it's previous state. Kevin Cashen offered a great example of this with pictures.
So, if this evidence is taken to heart, the multi-quenchers should be pretty happy. It proves that steel will retain the affects of thermal/mechanical treatments if it is not allowed to soak at or above critical for a extended amount of time.

Mr. Burke made some pretty intersting comments regarding testing done by Rex Walter that may offer some information on why this does work and how. There is no doubt that sending the test pieces to a lab will add fuel to the fire.

It is left up to the individual to decide what lenghts one is willing to go to achieve a standard. And it is left up to each individual to set the standard for quality they are willing to accept.

As a side bar, if you visit Swamp Rat Knives, a subsidiary of Busse Combat they describe their thermal treatments briefly. In order for their steel to perform the way they want their thermal process takes 40 hours. They describe the steel they are using as 52100 with Kryptonite. As I read the specs it became more clear that somebody else in the high perfromance world might be spending a lot of time on multiple themral processes.

We look forward to the results from Bill's final test subject as well as lab results.

Shane
 
Shane , shame on you ,you reference river rat knife heat treating ! They claim cryo refines grain, NO NO thats BS. Their steel is probably only one of a number of 52100 modifications.
 
Originally posted by shane justice


...In point of fact, it has been explained that if steel is subjected to mechanical manipulation, and then treated in a specific manner it will indeed remember it's previous state. Kevin Cashen offered a great example of this with pictures.
So, if this evidence is taken to heart, the multi-quenchers should be pretty happy. It proves that steel will retain the affects of thermal/mechanical treatments if it is not allowed to soak at or above critical for a extended amount of time...
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So there is no chance of my input being taken out of context, let me exlpain. I did show an example of patterns or structures in steel that can survive insufficient thermal treatments, I never said it was a good thing. Unless the steel is very hypereutectiod that little trick will take usable carbon out of play and could result in insufficient martensite formation. It is very interesting to look at but I never made a blade out of that piece of steel, in fact it is on my scrap pile where I found it.

I will also again stress, as I did in the original post, that this is a diffusion (and thus thermally) induced phenomenon that can be patterned through mechanical deformation, but it exists and continues to do so by the whims of the thermal treatments and not by mechanical deformation.

The idea of steel memory seems difficult to negate, while patterning and internal stress can hang on to some extent, almost any basic text on physical metallurgy will describe the annealing process in three distinct phases-

1.recovery: relieveing of residual stresses that can begin at temperatures as low as 600F From 600-800F this is usually referred to as stress relieving.

2.Recrystalization: The nucleation of new austenite grains that begins at Ac1, a temperature actually below the currie point (non-magnetic), and is complete at Acm (or Ac3 for steels with less than .84%C). During this time all prior austenite grain structure will be asborbed and replaced by the newly forming grains, if diffusion is allowed to do it's thing.

3. Grain growth: Once the available grain boundary carbides have been used, and the steel reaches its given grain growth temperature, the grains will then begin to feed off from each other and grain growth will commmence.

One does not need to go to the higher temperatures for drastic internal changes of the steel to occur. Many of the effects of deformation will start to be erased long before the steel begins to glow even a dull red. Some things do change this, strong carbide forming elements will be very hesitant to let go of carbon and will hang around and stabilize the prior grain boundaries, inhibiting grain growth until temperatures are reached to break their grip.

I don't know if one could use this discussion to group bladesmiths, If I could be grouped with any label I would place my self in the category of "rationalist".:)
 
Kevin and or mete,

Based on this quote from Kevin...
2.Recrystalization: The nucleation of new austenite grains that begins at Ac1, a temperature actually below the currie point (non-magnetic), and is complete at Acm (or Ac3 for steels with less than .84%C). During this time all prior austenite grain structure will be asborbed and replaced by the newly forming grains, if diffusion is allowed to do it's thing.
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Just exactly what temperature is Ac3 for 5160? Is it the currie point (non magnetic)? If so, then shouldn't the dot that I created with a ball peen hammer, as I explained in an earlier post, have been erased by the 9 heat cycles that I put the steel through post deformation?

I guess I should be classified as confused.:)

Rick
 
Ac3 is not a setin stone temperature, it is affected by alloy content, rate of heating, prior microstructure (no folks, no memories. Finer microstructures will go into solution quicker) and probably some more I am not thinking of. Under ideal equalibrium conditions the iron-carbon phase diagram shows that Ac3 for .55-.60C to be at round the currie point but 5160 is not a pure iron-carbon alloy.

I cannot say, for certain, what your dimple mark would be with a guess over the internet, but if you got anywhere withing the range of recyrstalization with your heat treatments I can say for certain what it is not. It is not the same austenite grain structure that was obliterated 9 times over.

I would guess that it could be either a layer of slightly lower carbon, or other alloy content, that got depressed deeper into the parent metal or you have patterened the fibrous flow lines within the steel. Since 5160 has been showing some of the worst inclusions and stringers in recent years, I would lean toward the latter. But, once again, this would just be a guess.
 
Thanks Kevin. I figured that something is going on (or not going on) in order for the mark to still be there. The mark is lighter in color than the surrounding steel if that's any clue. The steel was etched in Ferric Chloride.

I guess what is really important is that "It's not the size or quantity of your HT, but rather what can be accomplished by ones processes".

Rick
 
Originally posted by Rick Baum
I guess what is really important is that "It's not the size or quantity of your HT, but rather what can be accomplished by ones processes".
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While I would have phrased it differently, I think I would agree. If one heat treat method is more complex and has more steps and longer wait periods in between various steps, it begs the question "why", and "what benefits to the blade" flow directly from such steps.

There'd better be a payoff to something complex, as it increases the time spent (time is money... unless this is just a pure hobby, and wherein the more time you spend per blade, the more fun you have per blade). And the longer it takes and the more steps, I'd argue that (and I believe Kevin already has pointed out that) it makes it that much more likely you'll screw up some aspect, forget something, decarburize or overheat or UNDERheat a portion of the blade, be distracted with something else, have literally "too many irons in the fire".

Another of my favorite quotes, on balance and complexity:
Albert Einstein
"Everything should be made as simple as possible, but not one bit simpler."
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I take Einstein's quote as an elegant way of pointing out a couple things:
1. Don't over-complicate things... tasks tend to be more repeatable, more tractable, if they are simplified. There is elegance in simplicity.
2. ... but don't be a simpleton either... don't oversimplify things if doing so obscures or obviates important details, or completely misses important points, aspects, results. If something is very complex, then by all means use as much complexity as necessary to describe the phenomenon, or perform the complex set of activities if that is what it takes to achieve the outcome you seek.
 
Kevin: Maybe we are talking about something much different. Rex can tell me which side of the blade I hit with a hammer more than the other side by examination of the hardened blade.

I have a 52100 blade forged by Ed Schemp years ago. He purposely forged the blade using a drawing die on one side of the blade, flat die on the other. In the hardened and etched blade you can see the ladder pattern created by the drawing die on one side of the blade, the smothe flow of the grain resulting from the flat die on the other.

I believe Rick's experiment could be a valid display of the hammer blow if enough steel was initially displaced.

The old wootz blades lost their pattern because the chemistry went back into solution, not the grain flow. I believe: It was the grain size and flow that resulted from low temp forging that produced the blade they wanted, the wootz pattern was just a visable quality control event.

Are we talking about the same thing??

Back to complex heat treats and forging practices, it is easy to debate with no end in sight. If you wonder about it, you can't get an answer sitting at your computer, or delving in terxtbooks. Try some of the events and test your experimental blade against a control blade and compare them.
 
Mete,

I tempered a piece of stainless at 700 F. for 2 hours after double tempering at 400 F.. Why did the hardness not change???(!!!!) I am perplexed and can only guess that the temper had been set. It is on another thread here concerning S90V and was hoping you would chime in but perhaps you haven't seen that thread.

Sorry guys; I know this deviates alittle from the theme but at least it is pure HT stuff and I'm hoping to draw Mete's attention to it.

Thanks. RL
 
Perhaps secondary hardening? A drop off occurs in HRC after a particular tempering temp and then begins to raise again as alloy carbides precipitate. Hard to say for sure without watching the whole process. Hope that helps.

*Edited to explain myself a little more accurately. :cool:
 
Jason, what you explain makes sense to me. After all I do suspect these type steels are classified as 'secondary hardening steels'. I had not had it explained to me before as you just did. I am interested in your explaination. I do hope Mete has some thoughts on this. Thank you Jason. You have given me something solid other than my ignorant guess.

RL
 
RL, sorry I hadn't been following that thread. Crucible doesn't give the tempering hardnesses for S90V so I assume there is little change.The S60V doesn't change very much.More simple steels would change . The tetragonal crystal (elongated cube) of martensite looses carbon as the tempering temperature increases . The martensite then changes dimensions which can be measured through Xray diffraction methods .Highly alloyed steels make things more complex.
 
Roger I wanted to add
Mete is working on compiling this thread information and is going to
give it to Kevin C to add too and edit in his
thoughts, if all goes well...
The result of will be put on the knife making site I/We all have....
this should be good reading for a technical stand point .:)
and I think it will have your tests and results in it also.
I'm working out the format for the web page layout so it can be added to as needed..:)
 
Kevin,
My last post was not meant to label anybody. It was just an attempt to understand each side of the discussion. It was one for the sake
clarity, rather than the need to be divisive.

My friend Rick's question is a good one. His ball peen test can be studied by anybody who is interested. So can all of the processes that have been outlined here.

By the way, Ed was open and honest about his basic recipe for making blades. Will anybody from the single quench side step up with their treatements?

Shane
 
Shane,
some comments.

Earlier you defined two "schools" of blade smithing. One relies on triple quenching AND low temperature forging.
I can't see any connection what so ever to define somebody using single queching NOT to rely on low temp forging.
So called "aus- forging" is a hunders of years old German method (meaning really intensive care of low temperature, lowest possible).

An other:
on an earlier thread we discussed about edge quenching. I ended up the problem that at least with air- hardening steels we can't leave the spine unhardened (spine hardening in the air). Now I have got an answer making sense to me. I strongly recommend the web pages of "Teller Canyon Forge" for everybody to read (the paragraph about stainless steels twice).

http://www.tellercanyon.com/knives-and-steel.html

A lot of really good and well presented knowledge (not only "data or info") at a practical level.


(In my vocabulary (Finnish/English or somethig...) I call so called "stainless steels" as
"cromiums allo.yed with ferrite and everything else", but this is an other story, not very important here.)



pig
 
Graymaker,
very, very compact message.....

If you did mean the answer to the spine hardening problem it is in the material I referred to, if you mean something else....:eek:

pig
 
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