Triple quench secrets to be revealed?(or not)

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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.
 
I have been following this thread for some time, a most interesting discussion!
Does science lead and the art of the blade smith follow, or can it be the other way around?

When I started forging blades I purchased a number of texts devoted to the science of metals, I made up cue cards with the science on one side, and the definition on the other. One day I came to the conclusion that the science was interested and came from metals designed for other uses than cut.

I tossed the science into the slough in front of my shop and began to explore the simple world of the knife, free from the traditions that the science treads in.

Every blade smith has in his shop everything needed to test the knives he makes. We don't need the science to lead the way, science works best when it describes what happened rather than directs the course.

Now when something unexpected or a new development occurs, I send the blades to the laboratory and ask what information they can supply.

Many men of science remain snugly wrapped in the traditions of their profession and explore very little, others seek to explore new ground and leave their mark for others to regurgitate in future discussions.

Does steel have a memory? Rex can tell me when I have forged more on one side than the other from photomicrographs of the blade. The blade itself will tell me when it warps in heat treat. We go into heat treat with finer grain in the future cutting edge simply due to more forging in that area.

The finer the grain going into heat treat the lower the temperature it will grow, this is why multiple quench works. Long soak times on fine grain cab promote grain growth.

All of these events can be observed by any blade smith who asks the question why when something works or when he doesn't. The important question is - what for? when choosing what knife to make. The rest is simple, vary techniques and see what works. Cut what you want the knife to cut, if tough or strong is needed plan for it and test.

Rockwell alone does not predict cut, some hold on to Rockwell tests like a drunk holds onto a lamp post for support, while it is useful to some, there is more to cut.

The search will be very discouraging when the steel used varies, Every batch of steel is different. When working with the same steel by number from different manufactures each will vary.
The first bar out of a pour will vary from the last. Harvey Donaldson, A master at bench rest shooting found greater accuracy when he kept track of the bullets as they came from the lead pot. The first ten would shoot to a different point than the last 10. If these differences are manifest in a simple alloy like lead, surely they will find their way into the steels we use.

Fine grain is only one aspect to be achieved, an aggrigate can be stronger and tougher than an absolutely uniform grain.

This discussion has involved many variables, I encourage the blade smiths to consider the science, but your own testing will serve you well.
 
These kind discussions can be interpreted with many ways. All depends on the interpreter.

If we know 'enough' about this kind of threads, we have 2 possiblities depending on our basic character:

(1)We can say that taking a complicated topic into a thread we are going into a jungle to find some rare flower, we will not probably find it, because the jungle is too wide anyway, but we will find others as beautiful, hopefully.
(2)Or we can say: Bloody communication problems always arise and we end up nothing talking everything possible at the same timeloosing the matter itself.

If we do not know enough about this kind of threads, we can imagine to get a clear discussion about the topic and only it with a very controlled manner.

I statrted with an idea that "the triple quench" works and it would be at least possible to experiment one variable to get more light to the problematic behavior of steel. I did not say that the soak time is for sure a final solution, just making a hypothesis. Everything did seem to fit to make at least a hypothuesis to be studied.

Then we entered in the jungle and varied all tracks, paths and variables, sometimes keeping in the mind also the original question.
Eliminating all extra variables is a very big challenge- even it really is possible in a real scientificial study.
I think that many still believe, that it is impossible.

Has a steel a memory?
For sure in some respect. A steel "remembers in a way" when quenched that it was very carefully worked into a fine crystalline structure. Not too good example, excuse me!

In some respect a steel remembers it's previous state at the same way as "a cubic ice piece" melted once into water and rebuilt later into other shape remembers it's cubic figure earlier. Is melting a ice cubic into water sometning near, and how near, to heat a martensite back into austenite? (I know that austenite is not (always) melted, this is figurative speaking!)

Too much about that? But I continue a little bit:

Suppose we have a good austenite. We quech too slow (accidenly) part of it. We have a partial martensite and martensite in the blade. We heat it again into a austenite. Does the austenite remember?
Which part was a proper martensite which part was not proper early?

All kind of odd things happening too making the discussion damn fun.

I did read the Ed Fowlers invaluable book Knife Talk very carefully, even to be able to find editorial or printing errors (page 121 number 3/6 is incorrect, others too!).

I was blaimed to misquote the book in some extreme odd contextes! Misquote?! What for?!
Then I was blaimed to continue this kind discussion and answer to unfear critisism!

The jungle of discussion thread is for sure a big, interesting one and offers surprises too.

It still believe that it is not an offence but a normal and useful practice to present a hypothesis and to study. Facts are facts and people are people different from each other. A lucky thing, a person can't turn into a fact but remains a human person.

.............:D


pig
 
Kevin, when you say "wootzy" do you mean Widmanstatten structure ? Widmanstatten is the precipitation along preferential crystallographic planes.
 
Based on Ed Fowler's post- telling about steel's memory.

I would add some questions if we really have to think that a steel remembers something after it has turned back into a austenite:


(1) If we fail in quenching and fix the matter by re-quenching and the steel has a memory, is it so that a properly first time quenched part is a first class martensite and badly first time quenched part is a second class martensite?

A fine file glides all the way, but are there more precise tests telling that the steel remembers earlier quenches (heating similar all the way)?
How many of them? How?

(2) Are all smiths learnt all times wrong way, they are told to quench again to fix a mistake in the first quench (of course to be careful with extra heating to avoid the grain growth)?

(3) Why are we learning techniques to get a steel to loose it memory if it can't (annealing, normalizing...)



.............:confused:

pig
 
Kevins statement that lowering grain size also lowers hardenability should be paid close attention. If you haven't worked on grain reduction cycles in your blades you really can't appreciate just how this affects the heat treat of your blades. Lower hardenability=higher heat or faster quench or softer blade.
There is some very good info scattered around in this thread, you just have to shovel all the bs out of the way.
If it weren't for mysticism and science the popcorn people would go out of business. mw
 
The Guild doesn't list that Al has a web site.
One article on Pendray's Wootz:
http://www.tms.org/pubs/journals/JOM/9809/Verhoeven-9809.html

Widmanstatten... is this the pattern formed in meteorites?

Kevin Cashen
I must admit that I am a control freak and detest unknowns and rampant variables.
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Amen.

Disentangling variables is absolutely necessary in order to produce clean, crisp, clear results, and therefore achieve something you can learn from, especially if you wish to learn quickly and keep moving, keep pushing on to the next learning. (That was the spirit in which mete originally prodded this thread and RLinger's quick experiments.)

Incantantations won't do it, and poorly and/or randomly constructed experiments won't do it either. You must control as many variables as you can when you vary one other variable, or learnings get fuzzied up in the outcome. (and just because I used the word "experiments" doesn't mean you need a statistically controlled experiment with 30 trials, either, to allude to another current thread on BF).
 
Originally posted by Kevin R. Cashen
One thing that must be stressed, however is that there is a point of diminishing returns on everything and you can get too much of a good thing. fine grain size is good for strength but it significantly lowers hardenability and grain coarsening temperatures. If you are succesful in gettig the grain size too fine you could find that your quench isn't quite fast enough anymore and your Rockwell numbers will be a bit dissapointing.
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Now this is a learning for me... first I'd heard that super fine grain lowers hardenability.

Kevin Cashen, could I ask that you elaborate more in this area when you have time?

What steel(s) did you test in this regard?
What grain sizes did you observe during your test?
Could you comment on "where" with respect to grain size you saw hardenability drop off? I.e., linear, or is there a non-linearity... a point where it seems to drop off appreciably?

And if you care to, can you comment on grain size and toughness, grain size and abrasion/wear resistance and what you've found in these regards?

(I know, I'm asking for a research paper... ;) )
 
Hello Fellas!

Wow this thread has taken a turn for the better!

First I wanted to respond to something the gentleman from Fox Creek said a while back, he quoted me about using a two pound hammer, and suggested I use a six or eight instead to work the steel faster.

I missed reading that post until this AM and apologize for not
responding sooner.

I can use a six or an eight and when I am really feeling sparky I can swing a ten, one handed. I have also acted as a striker while my wife handled the hot end. It does go faster, but is it better? Because I work steel at low temps I prefer to work a bit slower. Rick made a comment about that practice earlier. While most folks I have talked to scratch their head, it has produced consistant, solid quality.

BTW, I use the flat side of a farriers rounding hammer. Flat dies on a power hammer will also work the steel very evenly as I found out at the ABS school. I prefer not to use fullers for this. The reason? Because I am going for a controlled movement of the "grain" without excess "distortion". (Using words very carefully.) These are my descriptions, not trying to tread on the toes of our metallurgists by using terminology imprecisely.

I want to thank Kevin for his explainations of the "wootzy" appearance of hyper-eutectoid steels. I learend a lot from Al
and hope I have not in any way distorted the facts of his work.
Wadsworth and Sherby did some pretty cool stuff. My own thoughts were only half formed, but Kevin's lucid comments brought them into focus.

I would add that your words on 52100 were to the point. Low temp, previous porperties will remain. Can I say that as an ok paraphrase?

My remaining questions would be along the lines of "What can "reading" steel teach us about our processes?"

I beleive if we pay attention and conduct practical tests, we will discover better quality blades. Can I say that without pissing anybody off?

That's the main reason I use the ferric chloride etch. I have
learned a lot by documenting each blade, finishing, etching,
and then testing. The tests and comparisons have helped me refine what I do.

Let's keep these ideas flowing...learning lots!

Shane
 
Originally posted by mete
Kevin, when you say "wootzy" do you mean Widmanstatten structure ? Widmanstatten is the precipitation along preferential crystallographic planes.
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It does not take on the same regular acicular pattern that traditionally is labled Widmanstatten, it may share the same preferential habit planes, as far as I know. Let me see if I can get away with this:
funwooz1.jpg
funwooz3.jpg


This is the bar that I played with, I also stamped an "X" before my initials. The surface is completely smooth and level and the bar was heat treated after the images were imprinted. As you can see the pattern is much less regular than traditional Widmanstatten but occasionally some of the straight crosshatching will occur within the patterning, if the soak time is long enough in their formation.
 
Originally posted by rdangerer
Now this is a learning for me... first I'd heard that super fine grain lowers hardenability.

Kevin Cashen, could I ask that you elaborate more in this area when you have time?...
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It is a fascinating topic and I will be happy to go into it when I have time, but right now I am late getting out the door because I fiddled around too long with the images above. Get back with you tonight.
 
Kevin, great pics! How many smiths you know etch blades as a part of testing?

You mentioned, fine crystals and quench time. Quench media seems to be a variable that hasn't spent much time being discussed. So far, vegetable oil, water, Mobil Vactra and Texaco Type "A". Which about covers the spectrum of quench speeds.

This might be another "How long is your string" question, but in general does the speed of quench media make a difference?

If my brain is working, there seems to be an correlation that looks something like:
fast quench = very hard, brittle
slower quench =less hard but tougher.

Does this idea jibe?

Of course I haven't accounted for tempering.

If you want I'll send you some Type "A" and you can play a bit.

Shane
 
I remember when Kevin did this experiment and posted it on Sword Forums. It really is interesting stuff. I took Kevin's photos and tweaked the gamma and contrast a bit to try to enchance the visibility of the pattern, and in particular the "XKC" in the first shot.

cashen.jpg
 
Widmanstatten -- Yes widmanstatten pattern is what you see in meteors. It is not however , necessarily acicular (needle like) but often is .Somewhere I have a photo of widmanstatten which I made in my very first metallurgy class.Though I really didn't know what I was doing and Widmanstatten was not the objective the result was so exceptional that it really freaked out the professors.I should find that.....I made very brief mention of grain boundaries earlier in this thread- the fact that adding about .005% boron to steels greatly increases the hardenability .The boron concentrates in the grain boundries and that is where the martensite begins to grow. Many things happen in grain boundries, good and bad, which may change hardenability, critical temperatures etc. .....Hadn't read the Pendray article in a while .It's in my computer now for easy reference. The phosphorous content is VERY high, far above permissible standards today. No wonder they had a problem forging it. And of course phosphorous concentrates in grain boundries !!!
 
Mete,

Is that because boran or phosporous will not go into solution and therefore have to reside at the boundries if they are to remain in the steel??

RL
 
Originally posted by Ed Fowler
.....We don't need the science to lead the way, science works best when it describes what happened rather than directs the course.
.......
Many men of science remain snugly wrapped in the traditions of their profession and explore very little, others seek to explore new ground and leave their mark for others to regurgitate in future discussions.
Click to expand...


I have to say that, unless I grossly misunderstand, that comment is pretty absurd and obnoxious, let alone insulting.
 
He said he " tossed the science into the slough". We'll just go on without him.........Roger, all alloying elements have some solubility, but when that has been exceeded they do other things . They may form carbides or other compounds and they may end up it the grain boundries where there is more room for them. Ifwe have a problem of too much phosphorous , we can't do anything about it just by HT. But forging will tend to spread out the Phosphorous and if we work toward small grains that means more grain boundries and thus the Phosphorous will be dissipated and the problems lessened. But of course it's always better to start with good steel.....Shane , I'm glad we're getting you're attention now.
 
Mete, thanks for that concise explaination. I had little trouble understanding the way you explained it.


RL
 
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