Triple quench secrets to be revealed?(or not)

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Pig,

That is just the way these type threads run off. Heat treat seems to be an exciting subject and even the most dormant subject matter that has to do with HT seems to wake up many effections. It is all very good. It is, after all, the single thing that makes a knife instead of something that only looks like a knife.

RL
 
To Rick Baum:I opened a new thread "differnent quenching methods". I hope you can get some se3nsible answer to your question eventually.

pig
 
Bill...

This is DaQo'tah, Thanks for your answer, but your answer leads me to another question. My question (much like Rick's to mete) deals with heating the whole blade, or just the cutting edge?

Here is what I am doing now with my 52100 and 5160 steels...
I heat the cutting edge then quench in Texaco type A quenching oil that was heated to 160.

I then waite 24 hours, the heat and quench again, waite another 24 hours, and do it a 3rd time, then I temper in a kitchen oven set at 400 for 2 hours, let cool for 24 hours,heat/cool, 24 hours, and do it a 3rd time.

So thats 6 days of work!

now I wish to try an experment,,I will use your idea to heat the whole blade in a kinda pipe I have (square tube), but how?..step by step do you suggest I do it?
 
We were trying to find information about soak times for 5160.

I found a web page:

http://www.dfoggknives.com/waterhardening.htm

Talking about "decent 2-5 minits soak time".
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Quote:

For example, when hardening 5160 in oil in my shop I look for a temp of around 1525-1550f... quench in water from this temp and the edges crack just about every time. Drop the temp to 1440-1460F with a decent soak time, like 2-5 minutes for example, and the same 5160 blade will get screaming full hard without cracking. I have found that this lower-temp/longer soak rule has worked for every steel I've used, and also in every case solved most all of my cracking/excessive warpage problems.
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pig
 
More Crucible soak times ; for 52100,4340,6150,4140M recommended soak time 10-30 minutes. So where do people get 5 minutes ???
 
Mete,

(First let me say I'm just a heat treating data sponge and I look forward to reading ALL of your posts and take your information very serious.)

So where do people get 5 minutes ???
Click to expand...

So to give you an honest answer:

I was told by a long time blade smith that that's what he's used and works well. Also, I was told that the published soak times are based on a 1" cube. Therefore if 1" takes 30 minutes, then a 1/8 would need about a 4 minute soak (plus what ever to just stabilize the oven).

Just what I've heard.

Steve
 
The documented soak times I've read always deal with a 1" minimum cross section...which of course is never the case with a knife.

A complex alloy like S30V should by nature need a longer soak time to diffuse the alloy (or so I think ) than something much simpler like 52100.

I don't think there will ever be a totally level agreement on this subject. There are always going to be people that think their method is better for XXX reasons.

Just as a side note, I'm in the same line of thinking as Burt.

I use a digitally controlled motlen salt bath for heat-treating, and I feel that the extremely even heating (conduction) is absolutely the best way to go for quality and consistency.

Nick
 
So I was useing 5160 steel to learn how to make knives. The problem was that although I could make the 5160 knife very sharp when I was done, the darn thing would seem to go dull just by looking at it.

Well, I knew I had to try something different, so i wrote to Mr. Ed Fowler and got some new advice for a slightly different style of Heat treating than I was useing. Now I have changed to doing this...
1- several times as I forge the blade in my coal forge I quench in cold oil.

2 - after I finish forgeing the blade, I heat the blade and just watch it get cool, it turns colors back and forth. do this 2 times

3 next I heat and allow to air-cool to a cold temp

4-then heat in forge and allow to cool in forge for 7 hours

5- when the grinding work on the knife is mostly done, I heat-treat , heating only the cuttine edge, quenching in oil, edge only diped into 135 oil and not the 160 temp oil I was useing .

6- temper in a 350 oven for 2 hours then test, (down from 400 temp I was useing)

My question...

I just finished my first test blade useing this pattern given me by Ed Fowler and I just etched the blade and it shows the best deepest quench lines I have ever seen!...and the knife is very very hard on the cutting edge,,,and as I test the knife in cutting tests I see that this test knife is the best cutter I have ever made....However, could I have just heated once and dipped in oil once and got the same result?

I dont "think" so, but Im new to this sport, so I dont know,,,Ed seems to have given me a pattern to keep that has really worked for me...He clearly knew what to say to me to get my blades to cut,,,,and thats the whole point,,,,,but was it accident?. or was it just a better way to work with 5160?

you guys keep talking about a 5 min soak,,,but I just heat and quench,,,with but a few seconds of the steel up high in temp.

However then you guys talked about the 5 min needed could well be added up from all the heating?...well,,,if thats the case, then I have also ended up by accident with around a 5 min soak I would guess....

(I have no way to know how long I kept my knife up in the higher temp range as I did the pre-quenches as I forged the blade,,,but all told I would bet I was over 5 min for sure)
 
D.Forge I have not read Ed Fowler's book but from all the comments it seems that his methods are always overly complex. Experienced or not there is no way that you can uniformly heat with a torch. And you can't accurately tell temperature with the eye. I tried that once doing it every day and checking with instruments and the best I could do was 25F+/25F- .Nick has the proper and best way - molten salt. Your HT - # 1 I don't understand ,# 2 I don't understand, #3 normalize, #4 anneal ( Iwonder why 3and 4 are both necessary one might be enough since 5160 is a simple steel ) # 6 I prefer tempering at least 400F. Do some reading. Thanks Nick and Steve for why 5 min,
 
Originally posted by mete
D.Forge I have not read Ed Fowler's book but from all the comments it seems that his methods are always overly complex. Experienced or not there is no way that you can uniformly heat with a torch. And you can't accurately tell temperature with the eye. I tried that once doing it every day and checking with instruments and the best I could do was 25F+/25F- .Nick has the proper and best way - molten salt. Your HT - # 1 I don't understand ,# 2 I don't understand, #3 normalize, #4 anneal ( Iwonder why 3and 4 are both necessary one might be enough since 5160 is a simple steel ) # 6 I prefer tempering at least 400F. Do some reading. Thanks Nick and Steve for why 5 min,
Click to expand...

that should rufle some feather Haha

I was writing a big rant on some of the things you wrote here
and I pushed the back button and lost it..probably a good thing anyway.

I do want to point out three things you said.
I tried that once doing it every day and checking with instruments and the best I could do was 25F+/25F-
it may be just the best you can do..are you saying no one can do it better than you?

you can't accurately tell temperature with the eye.
you might be right BUT you can't say a man can't tell if it's at the right temp by eye to get very good results..
tell the old sword masters that it can't be done..

Experienced or not there is no way that you can uniformly heat with a torch
I beg to differ, there are ways to get it done
and you do have a window to work with. LOOK
I can't walk a tight rope but some guys and gals can and
do it very well,, with-out watching them fall off I'm
not going to say they can't do it.
Nick has the proper and best way - molten salt.
but if the temp gauge is out of tilt
it's no better then any other wat is it..
rant off
:)
 
Mete...

I got interested in starting to learn about making my own knife a few years ago. The first thing I did was go get a book called HOW TO MAKE KNIVES.

This book opened a door for me, and (although the photos were way to dim to see what was going on) I started reading and studying it closely.

However at one point in the book, the knife maker says that he always sends his knives away to some other place to be heat treated. Then the books picks up the "how to make a knife" story at the point where the (now heat treated) blade comes back to the maker.

Well, when I read that part of the book, I thought to myself,,,"well thats was kinda pointless for me to learn..." because I knew that I will never be sending any of my knives to another guy to HT. Way too much money to spend on something that should be something every guy should know how to do anyway.
the idea of a salt bath also sounds like it would be a bunch of money up front too.

Then I was introduced to Ed Fowler and just knew that what he was saying, I could do to!. he used a forge, an O/A torch, and an old kitchen oven,,,,hey, that stuff is within my budget!

Thats why I seek to understand whats going on in the many different quenches that He does,,,for it seems to work,,,and I am starting to see good results as well...

Lets just say that Ed Fowler and his experments with many quenches actually works,,,That for some reason doing many different Heat treatment oil quenches does something very good to the cutting edge of a blade over a single quench,,,I just seek to know why,,,and how to make my own many quenchs better at doing whatever it is that happends in such a quench.

Ed shows us how to Heat treat by useing a O/A torch on just the cutting edge,,,But I seek to understand what would be different if I heated the whole darn blade, then just dunked in oil the cutting edge?

The type of knife I wish to be known for making, is one that will never fail, it will never break...This means that unless the Heat treatment you are useing can allow you to clamp your knife into a vice and then stand on the handle and jump up and down with NO chance of the blade snapping off, then it's not correct for my needs...My work knives are very important to me, I use my knife on the job about every 15 min to cut something, many times with lots of co-workers and important people watching me,,,and many times Im in the dark as to the cutting, or may be trying to cut something that is under water...I like Ed Fowlers ideas, and am trying as best I can to learn them better with each blade, however Im not blind to other ideas,,I seek to understand how I could use any other good ideas to end up with a knife I can trust with my life, (or at least my fingers, remember they dont grow back)
 
I use a quench process smiler to Ed Folwers and have very good results. The process may seem completed and repetitive but in my cutting tests it has proved to make a better knife. Ed is a good men to listen to as his Knives speak for them selves. Gib
 
The documented soak times I've read always deal with a 1" minimum cross section...which of course is never the case with a knife.

A complex alloy like S30V should by nature need a longer soak time to diffuse the alloy (or so I think ) than something much simpler like 52100.

I don't think there will ever be a totally level agreement on this subject. There are always going to be people that think their method is better for XXX reasons.

Just as a side note, I'm in the same line of thinking as Burt.

I use a digitally controlled motlen salt bath for heat-treating, and I feel that the extremely even heating (conduction) is absolutely the best way to go for quality and consistency.

Nick
 
Greymaker, I am not saying that you can't make a decent blade with eye and torch and Fowler has lots of experience . The fact is that with a properly operating salt bath control is better. D Forge , the hardening only the edge question - hardening the edge will give you martensite on the edge and pearlite/ferrite on the spine.If the spine had martensite it would be stronger. For your dream of never breaking (LOL) you should go for bainite and for a better edge perhaps O1 tool steel. In any case for all of you what I am trying to get across is that if you do a certain thing in heat treating you should know exactly why and what you are getting. That's why I keep asking WHY??
 
It is a little known fact that Heisenberg discovered the uncertainty principle while working on a set of kitchen knives.

As you might recall the principle is quite simply:

The more precisely the position is determined, the less precisely the momentum is known in this instant, and vice versa.
Click to expand...

He was, in fact, testing one of the blades on his new kitchen knives. After passing the brass rod test, he decided to test the blade while shaving Schroedinger's Cat. However, no matter how hard he tried he was never quite sure where the cat was or even if it was alive. This lead to a lot of frustration and hacking.

And he summarized the event in a paper containing the famous quote.

So, take heart testing knives is full on uncertainties.

Steve
 
METE....ummm..okayyyyy..

now when you say I will get "martensite on the edge and pearlite/ferrite on the spine"

Is that a good thing?

and when you suggest I turn to "bainite" to get the type of blade steel I need for my work,,,well,,okay, but what does that mean?

It's like this, I got the tools that I got,,there is no way im going out to get a new knife making tool at this time.

I am afraid that some of the techniques and tools you guys use to get a killer edge on your blades will always be outside my ability to reproduce....

.I do order 52100 steel from Rex Walter from time to time, but most of my knives will always be made from cheap 5160 steel, found where I can find it for free.

call me a dreamer, But I still think that with a bit of work, study and listening to the right advice, I will be able to make the type of high performance knife blade that I need.
A blade that will not embarrass me when borrowed or sold to someone who trusts my skills. And not fall apart just because a guy used it to climb out of a hell-hole somewhere...to never give up on me no matter what, and always be able to the 3 things I think are most important for a knife to be able to do.
1- cut and cut well
2- be easy to sharpen
3- not break
 
This discussion is the best example of difficulties of the human communication I ever met! Much better with this than to explain HT:

Initially I did present a theory, which might explain why triple quench really works. Read the word might! Only if a test shows the theory is a fact then HT is easier. Read the word test.

Of course we can keep the old working difficult method if we are too lazy to test! (And the test can show we must keep it anyway.)

About the metallurgy books: I have read and found useful to understand perlite, bainite, martensite and many principles too.....However, I can't get my idea to be understood with mete. Even I think that I understand what he is saying and agree with him and think I said the same thing, he misuderstands me mostly. So, reading a book makes you perhaps to undersand metallurgist but not cabable to get yoursef to be understood by one.

Try to keep things simple.
Smiths are always used some sensible techiques to make the spine soft (or spring like).

I opened a new thread "quenching techiques" and listed old used techiques as an introduction:

(1) Heat evenly and quench verically to prevent warpage.
Temper the spine separately by torch or other method (edge in water).

(2) Heat only edge and quench horizontally to get though spine (Ed Fowler).

(3) Heat whole blade and quench horizontally only edge. The spine cools more slowly and is then toughter.

(4) Heat evenly and quench verically 3 drops.
First time thin edge is martensite (fully hardened steel), but thick spine is not fully martensite.
Second time prevents still hot spine to temper the edge too much and cools spine more.
Third time cools also the spine, but so much time spent it is not brittle martensite.

(5) Pre quench whole blade. Temper whole blade to "spring level or softer".
Heat only the edge (spine on water). Quench.

Of course these techiques make use of combinations of perlite/bainite/martensite.

Perhaps "DaQo'tah Forge" taking the matter seriously finds some interesting from this list. In fact the aim of these techiques is to get hard edge and the spine you can "jump on". Some can be bad, some can be good, some can be good for steel x, some for steel y.

I did a web search "www.google.com" with searched words "metallurgy terms"- huge number of hits.

See for example:
http://swordforum.com/metallurgy/ites.html
(They have a nice idea to make terms simple and understable for smiths, everybody do not that.)

pig
 
Pig,

I find it difficult to understand your frustration. This is a subject I have learned is perpetually frustrating to come to agreement with. You, mete, and I and the rest of us will never completely concure. Even the industry itself admits there is much conjecture concerning many aspects of HT theory. And - these are the people that have the formal educations and the expensive equipments.

I have my adolescent beliefs based on advise and limited experiences. I feel myself blessed in a ability to recognize expertise, but the rest is to me to learn from them and prove to me them right or otherwise by my own works. If I were asked I would suggest that I believe mete is solid in what he says and rather than pick at it take his advise as a foundation to work with.

Sure is a great thread. RL
 
Rlinger, basically I agree upon everything you say. In addition, I think that all of us have different "frustration tolerance" and even more importantly different reasons to be frustrated.

Mine is that I clearly see that even discussing is good and can continue for ever and take different useful directions we can and will then forget the initial question.

Testing was in my mind for purely parctical reasons (to get something real out of this).

To my mind, we can't just pick up ideas looking reliable, but in the best case get well controlled reliable test.

I think this is very much in line with your opinion about different ideas newer ending. After reliable tests, there are not so many different opinions, I hope (I mean this single matter).

Oops! One more thing. Is my mistake that this dicussion group is literally "discussion group", so there is perhaps an other group for suggestions to practical tests?

No hard feelings tough- I hope!
And excuse my impatience, "a natural born gift", unfortunately.

pig
 
Rlinger did straigten me (by reason) and did say good things about mete. Good.

I got an idead.

Let's start from an empty table.

(1) mete do not believe triple quench to help

(2) mete knows about importance of the soak time

(3) mete thinks smiths are wasting timen with triple quenching

(4) mete knows that smiths respect his opinions (rlinger for example)


Why mete can't back up me a little bit and say: "It is useful to make a new test with soak time"?

Mete pick up your choice, is (1) or (2) correct by your opinion:

(1)
I think that if we organize a new test with soak time, it is at least possible that results with single quench and proper soak time are as good or better than results with no soak time and triple quenching.

(2)
I do not believe results to be as good or better.


The steel of Ed Fowler was 5160 and he tested only rope cutting.

pig
 
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