Triple quench secrets to be revealed?(or not)

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Roger is going to send me the samples to break and check grain size. I will check at 10x magnification. As for photos I can only do 1:1 and enlarge digitaly. My postings are terse ? well it's always been that way, my college thesis was much smaller than anyone elses. The view through my metallurgists eyes may be a bit confusing but maybe I can expand. We can strengthen the matrix (martensite) by adding carbon until we saturate at about .85%.Other alloying elements will also do that ,some of the chromium, vanadium etc will go into the matrix.Those elements will also change toughness etc. Beyond .85% carbon we then get carbides ( very visible at 1000x) which directly improve wear resistance. It's the old story of balancing properties.Yes I've been involved in pushing material to it's very limits but only on rare occasions. So I'll keep the 400F temper and have a nice stable tough structure.It would be nice if someone from perhaps Camillus would give us a lesson of how they choose steel and HT for a knife.It's the same with everything ,if I want to have 44 mag performance I get a 44mag, I don't try to push a 44special to 44mag levels( as many do!! ).
 
Arrgg, I have had to register with yet another forum, the shop works gets even farther behind:( . It was mentioned to me that I had been briefly cited in this thread, thank you for the confidence shown in using me for a source in any form. But I would like to clarify my stance on "cycling" steel through transformation temperatures. I will do multiple normalizations on steel to achieve different affects in the internal structures, and will even utilize the vast amounts of points for nucleation offered by martensite, and the finer structures created by rapid heating and cooling through Ac and Ar, in those treatments. Especially on steel that has gone throught the trials of forge welding. But I do not practice multiple quenching. I preffer to do it once, the best I can, while being in control of as many variables as possible.

While Mete may doubt my reasoning for more than one normalizations, I must agree with him on the quenching.
 
Kevin, we have spoken about this on sword forum where I go by the name Robert C. There you explained that while the metallurgists normalizing is 100F above critical the blade makers normalizing is subcritical. And pig thinks there is just a problem with finnish/english. Anyway welcome to the forum Kevin your comments will be very valuable.
 
Kevin, that was me that mentioned your use of quenches during the thermal cycling of a steel as it is being forged. :o Please forgive me if the wording or context of my post led anyone to believe that you advocate in any way multiple quenches during the hardening phase of heat treating! I know you don't and in reading my post again I don't even know why I brought it up since this post is precisely about the use of multiple quenches during the heat treament.

Chalk it up to random brain firings and posting too late at night I suppose. :( It was certainly not my intention to cause any confusion as to your methods which are backed by sound metallurgical principles. In retrospect my post reads like I was trying to "name drop" or bandy your name about in an effort to support a particular point. Again, my apologies.
 
Originally posted by Silent
Kevin, that was me that mentioned your use of quenches during the thermal cycling of a steel as it is being forged. :o Please forgive me if the wording or context of my post led anyone to believe that you advocate in any way multiple quenches during the hardening phase of heat treating! I know you don't and in reading my post again I don't even know why I brought it up since this post is precisely about the use of multiple quenches during the heat treament.

Chalk it up to random brain firings and posting too late at night I suppose. :( It was certainly not my intention to cause any confusion as to your methods which are backed by sound metallurgical principles. In retrospect my post reads like I was trying to "name drop" or bandy your name about in an effort to support a particular point. Again, my apologies.
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Don't sweat it at all, I am quite flattered that anybody would want to use the opinions of little old me in their argument. You used my views in the right context, but internet discussions are ripe with misunderstandings and I thought I should nip this one in the bud as far as my quenching techniques are concerned. I am quite impressed with how well and level headed this thread appears to have played out. Often dissagreements over something as mundane as heat treat techniques can get a bit heated. My compliments and respect to you all.
 
Originally posted by mete
Kevin, we have spoken about this on sword forum where I go by the name Robert C. There you explained that while the metallurgists normalizing is 100F above critical the blade makers normalizing is subcritical. And pig thinks there is just a problem with finnish/english. Anyway welcome to the forum Kevin your comments will be very valuable.
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Actually I cannot speak for any other smiths but myself. I know that many do use subcritical heating for the intention of grain refinement. I use normalizing ranges both above Acm (I preffer hypereutectoid alloys, with the exception of L6) and at lower temperatures, depending on whether I am looking to equalize things or refine them. I try to work within the estblished tenets of proven metallurgy whenever possible.

As for my comments, I think you are more than capable of handling this one, and seem to be doing so just fine.:)
 
Mete,
There you explained that while the metallurgists normalizing is 100F above critical the blade makers normalizing is subcritical. And pig thinks there is just a problem with finnish/english.
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:D :D :D :D
You save my day!!!!
What a sense of humor, good- ever speaking about .....

By the way, my metallurgy high limit is just to recall as correct also by my previous knowledge:
. We can strengthen the matrix (martensite) by adding carbon until we saturate at about .85%.Other alloying elements will also do that ,some of the chromium, vanadium etc will go into the matrix.Those elements will also change toughness etc. Beyond .85% carbon we then get carbides ( very visible at 1000x) which directly improve wear resistance. It's the old story of balancing properties.Yes I've been involved in pushing material to it's very limits but only on rare occasions. So I'll keep the 400F temper and have a nice stable tough structure.It would be nice if someone from perhaps Camillus would give us a lesson of how they choose steel and HT for a knife.It's the same with everything ,if I want to have 44 mag performance I get a 44mag, I don't try to push a 44special to 44mag levels( as many do!! )
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But:
hypereutectoid alloys
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Is beyond my just basic knowledge :footinmou

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Dear friend John,
I am glad to say you are wrong!


There are mental funny games nice to play sometimes but there are other things which really matter (old respectable tradition). I can't resist to participate also to games if somebody wants to. Also triple quenching is important problem and we must be open minded. It do not mean that to be open minded with testing we forget about other basic things.

I am a humble blade maker also as you are.
I and you are facing practical problems to make good knifes.

For example at this moment I am thinking more about very old German tradition "aus-forging" and "edge packing".
(terms from a nice book of Jim Hrisoulas known as "Atari"). I think that there is really something important with aus-forging and edge packing (metallurgy would be beyound our limits if it is in such a simple thing as triple quenching).

I am building a simple helping tool for edge packing and a tool to make esily "tang shouldes".

Discussion of triple quench is, however, interesting single topic something to do with metallurgy too.


Please, do not be confused about my talk ! I do not think that we have two enemy camps metallurgists and smiths or we must pick up our own side. If we must pick, mine is the smith camp.


All the best: pig (Tuomo)
 
Pig, Some of the things I talk about would be much more easily explained with drawings. But I will keep dragging you through and hope a few things stick. But don't get intimidated with fancy words. Eutectoid means .85% carbon , hypereutectoid means more than .85% and hypoeutectoid means less than .85%
 
Originally posted by Kevin R. Cashen
... and will even utilize the vast amounts of points for nucleation offered by martensite, and the finer structures created by rapid heating and cooling through Ac and Ar, in those treatments.

While Mete may doubt my reasoning for more than one normalizations, I must agree with him on the quenching.
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I use normalizing ranges both above Acm (I preffer hypereutectoid alloys, with the exception of L6) and at lower temperatures, depending on whether I am looking to equalize things or refine them.
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Mete, thanks for the elaboration on the 0.85% point... that helps a good bit in understanding. ALso on the hyper/hypoeutectoid definitions. Simpler than I had feared (which is good).

I'm lost on the "points for nucleation" comment, and I suspect Ac and Ar and Acm are well known temperatures (to metallurgists and some smiths) on the heat treat phase charts. But I'm guessing.

Help please? :confused: Maybe with a link to a phase chart that illustrates?

Also, anyone who knows... what is the general understanding from the science of metallurgy about grain refinement... how much does material toughness depend on this parameter?

What are the other strong drivers of toughness (Silicon in Shock Resistant steels (e.g. S7) is one example, low to medium carbon is another, fairly low alloy level seems to be another very general one, with something like CPM3V being about as "souped up" alloy-wise as I've seen for a fairly tough material).
 
Toughness is achieved by a combination of things .What we don't want is gross grain size from overheating or very long times.That will certainly cause big problems. Kevin knows his metallurgy and with skill and experience can manipulate things to give exceptionally small grain size.That means knowledge of precise transformation temperatures Ac (on heating) ,Ar(on cooling) .He is looking for increase in the nucleation points, that is where the transformation starts. More nucleation points , smaller grains. I read a techical paper recently and the metallurgist commented that there are many things about nucleation that remain a mystery. Small changes in alloying elements can also have great effect. When one of the knife makers switched to BG42 he commented that for the first time he was able to bend a blade before it broke , at full hardness.So grain size , composition and heat treatment all play a part. Eutectic and eutectoid are terms that describe certain characteristics of phase diagrams. I wouldn't even think of dealing with that subject in words.Just remember .85% C as the point that the martensite will be saturated with carbon.
 
I would like to apologize for the over technical terms and $5 words. Folks who know me, know that I myself hate it when eggheads throw huge techical terms out, when simple ordinary terms would work. But in this instance I did it as a time saver. Much of my comments were for Mete and, in light of that, I could get the job done in one sentence instead of the entire pragraph required to flesh out the details. I guess I was leaving the page-long explanations to him :D . Now if I could get him to polish some of those blades in the shop for me also ;) .
 
Things are going to very "high tech"!
Nothing wrong with this in principle.

I try to remember what "rdangerer" explained to me.

Perhaps some "reader level" summaries would be useful in addition to exact metallurgy? Yes?/No?

Basically only one thing bothers me- I am not too serious- but I really think that somebody (in addition to me) can think that "user level tests" or "black box tests"- computer system language not finnish/english- are important.


Then we do not need to know exactly which scientifical factor is making the result, but are convinced because "it works" (as rope cutting). Of course, it is even better if we know everything, I am not saying that nothing wrong to undestand all!

I think that more and more because "high tech"- tests are so difficult. Are they, did I misunderstand?

Am I the only one thinking this way- really seems to be more and more, but.....?

WELL, I DO UNDERSTAND THAT NOBODY ELSE IS NEVER SUPPORTING ME IN THIS MATTER.(I wonder why- but so be it!)




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Originally posted by pig
Things are going to very "high tech"!
but I really think that somebody (in addition to me) can think that "user level tests" or "black box tests"- computer system language not finnish/english- are important.
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Ok, I'll try to respond to your question.

User level tests are fine, good, necessary, helpful. Especially in the hands of an individual who has done very similar tests in the same manner. One individual can often draw good conclusions about how heat treating effects the finished product's actual field performance if they are careful to replicate their testing in a consistent manner (lots of variables, in heat treat, and in blade production, grinding, sharpening, and physical force in testing).

The problem comes in comparing one person's tests with another person's tests.

The machines used to test metal properties aren't perfect, but they do tend to offer more repeatable results. So CATRA, charpy tests, Rockwell hardness tests... if machines are calibrated occasionally, these tests offer some relatively consistent results that allow cross comparison. Rockwell tests are not difficult to make, just have to pay the $$ for the machine and make sure you have a reference block against which to recalibrate it periodically. Analyzing grain size can probably be done by anyone through experience ... with 10X magnifying glass ("Loupe") and/or through etching (apparently). Charpy and CATRA? Yes, those are expensive machines. Any of us could learn to run one, but very pricey, therefore impractical for most makers... unless they send blades or heat treated material samples out for testing.

But there are certainly tests that can be done by hand to gauge relative toughness.

If I said "Heat treat X yielded a tougher material than Heat Treat Y when I chopped against the base of a nail hammered into a board at 45 degrees", others might have a hard time convincing themselves of those results if they tried to replicate... lots of variables involved to explain. How hard was the nail? How hard did you swing? etc.
 
Rdangerer thanks, you did explain at general level the matter about testing very clearly and correctly too to my mind.

Then, unfortunately, also a special matters connected to the history and human factors can come into the picture case by case.

This case the history is that Ed Fowler did a famous well documented and published test about triple quenching with user level rope cutting test (about 130 cuts to dull....).

Human factors:
-Smiths do not understand advanced metallurgy and this creates difficulties to be convinced about new results expained by metallurgy terms
-Smiths are very practical oriented
-Smiths have great belief on authorities, it is far more difficult to believe on a contradictory result with an authority than just an other new result
-.......

I do not want to be stubborn, just explaning if you don't happen to know.
I do not want to argue and be persistent, please, continue doing good job! I am slowly begin to face the facts. Did I hear somebody to say: "At last dummy pig, even your name tells a lot!"?:D..........:D:D:D!



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Pig, I sent the test pieces to Mete yesterday (Wednesday) and I should expect he get them by tomorrow or Saturday. He will check the grain and I trust he reports his determinations here. I also trust, although I did not ask him to, he be willing to send these samples off to another of us for viewing.

Pig, I am with you all the way in the argument for use testing. In fact, I believe there is nothing like a field test under actual usage conditions. As an example: stand there and cut all the rope and whatever but there is no test like actually putting the blade to the use it is made for under the conditions it will actually be used in. If its a skinner I can stand here and cut 200, 300 foot of cardboard and say boy I am really happy with this one - but give it to a meat processor and evaluations can change real quick.

Pig, you started a great thread, one that will in the end completely satisfy none but a thread of great interest in foundation to all that really want to learn the most important single aspect of blade making.

RL
 
Thanks rlinger about your kind words and forgiving me:

Pig, you started a great thread, one that will in the end completely satisfy none but a thread of great interest in foundation to all that really want to learn the most important single aspect of blade making.
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At this moment I build up some forging tools for "edge packing".

Last Chrismast time I did build up my first computer. After my retirement (because of severe illness) I did think it would be nice to do something with my hands, I earlier always did buy all my computers ready made from a shop.
So I am proudly writing this with a self made computer (the power on button is a big bolt with a resisting spring, spring from a HW store- I know how to harden and temper (to blue) a spring, but....!).

Also if anybody interested in computers I did write an article published in the American BYTE- magazine July 28 this year http://www.byte.com/documents/s=7788/byt20030728/. The title of the article is "The Tortoise and the Hare" (I explain how and why a new 2.4 GHz Pentium 4 processor can be sometimes SLOWER than old Celeron 566 Mhz). I have this P4 processor in my current computer. I found the odd behavior and figured out, experimented (tested) the reason.

Sounds familiar, similar to the triple quenching?

(I found the reason testing my self made simple operating system kernel for Intel processors. Any interest? Link is http://www.evitech.fi/~tk/)

Well, I did tell a lot of my work.
The reason is (being defensive) I can imagine many think I just argue and make noise (I am the first to say that I do that too!).
:D.......:D:D:D
(Actually I use most of my time laying on my sofa and watching tv movies, I was telling what I am doing the short time on my feet or on my bottom.)




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Pig, My retirement should be peaceful too, and usually is but yesterday I had to chase away a bear that tried to get into the house. A two year old, parents today just don't teach their kids manners. Today I broke the samples - the triple quench appears more brittle.Gave details to Roger.
 
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