Good HT article in "Blade".

[Kevin R. Cashen]

Tim Zowada, has a very good, very basic, heat treat article in the latest issue of "Blade". There are lots of requests here for simple HT information so I thought I would point this one out. Sorry, he doesn't promise that you can make a super blade out of scrap steel using a Bic lighter, but he does manage to cover the basics in a few simple paragraphs.

I would also like to take this opportunity to help Tim out with an error that was probably done in the final edit or the printing, I have already got 2 questions about it in the last 24 hours. 1084 must be cooled from autenitizing to below 1000F. in less than a second to successfully harden, not 100F. Since Tim knows this as well if not better than I, I am assuming that the extra zero was lost after the article left his hands, or his fingers failed to hit the right key at just the right time, as mine continuously do.

 

[Matthew Gregory]

I was wondering whether or not ANY oil would actually manage to pull that off... or, I figured you and Tim were demonstrating how to make a new 'supersteel'!

Great article! Truly a breath of fresh air in Blade... hope it continues.



OT, Kevin, you still need something from me that I promised previously. I'm working on it, please bear with me!

 

[Alan Molstad]

1084 must be cooled from autenitizing to below 1000F. in less than a second to successfully harden,

Would a good , clear 'hamon" show you that you did cool the hardened edge as you say?

Or can a "Hamon" show the effects of other things becides the cooling was correctly reached?

 

[David Wesner]

What type of an instrument does one use to measure data like that. Or is it only through examining the grain structure under magnification that we ("we" meaning small custom blade shops) can determine whether we have successfully and correctly went through Ac1-2-3 quenched to below Ar1 (bypassing the potential for pearlite) reached Ms (within the TTT curve time for the material) and arrived at Mf without to much retained austenite. (please correct any error's on my part ) And if magnification is the best way for a small shop, what is the optimum power of magnification to examine this. I ask this after having read many of your articles, and with the hope of accurately matching quenchant to material through my own tests & results. Not because "john doe" at "johns steel shop" says it is the correct speed quenchant (is that really a word ?? )

 

[mete]

We start out with the TTT diagram ,not an absolute but a good guide. The distance from the base line to the 'pearlite nose' tells us how fast the quenchant should be . The amount of retained austenite is determined in great part by the austenitizing temperature .If you have a significant amount of pearlite you will not get the proper hardness. An additional check would be a microscope ,usually at 1000x .The low hardenability steels such as the plain carbon ones like 1084 will require the fastest oil quenchant and for some water can be used .If the quenchant is too fast it goes 'ping'.

 

[Stacy E. Apelt - Bladesmith]

Alan, The hamon shows nothing about the hardening of the blade except that the edge got hard and the rest turned to pearlite.That is a function of the clay coating,not the quench speed.It takes proper shielding with clay,a fast quenchant, plain carbon,and moderate hardenability to get a good hamon.The transition point is Troosite, and is the hamon.Do a search on "Hamon" and you will find several good threads on the topic.

 

[Alan Molstad]

Alan, The hamon shows nothing about the hardening of the blade except that the edge got hard and the rest turned to pearlite..

Thanks, thats actually what I was hoping to find out from the hamon anyway....

Getting the blade hard is the point of my quenching the cutting edge, so it is nice to know that I will be able to see right away if that happend.

 

[David Wesner]

We start out with the TTT diagram ,not an absolute but a good guide. The distance from the base line to the 'pearlite nose' tells us how fast the quenchant should be . The amount of retained austenite is determined in great part by the austenitizing temperature .If you have a significant amount of pearlite you will not get the proper hardness. An additional check would be a microscope ,usually at 1000x .The low hardenability steels such as the plain carbon ones like 1084 will require the fastest oil quenchant and for some water can be used .If the quenchant is too fast it goes 'ping'.

Thank you mete

 

[Kevin R. Cashen]

What type of an instrument does one use to measure data like that. Or is it only through examining the grain structure under magnification that we ("we" meaning small custom blade shops) can determine whether we have successfully and correctly went through Ac1-2-3 quenched to below Ar1 (bypassing the potential for pearlite) reached Ms (within the TTT curve time for the material) and arrived at Mf without to much retained austenite.

I think I should first point out that we are all "we". My shop is smaller than many, forging area is 14'x20' and finishing area is 16'x20', with a smaller room added on to house my testing equipment, Tim Zowada's shop is even smaller. This is my view on the matter, if you wish to make a decent knife that will cut most things quite well and be happy with how it does it, a file test, providing you realize its limitations, and just cutting on things is enough to let you know you are on track, either it can perform as a knife or it can't. My scopes are for research well above and beyond this, and are an important part of my arsenal in combating the B.S. that has thoroughly covered knifemaking. I believe Tim has a scope for much the same reasons.

I just got a rather expensive shipment of lapping a polishing equipment to be able to properly use my microscopes more, so let me say that it is not just a matter of getting the scope and going to it, it is quite involved and costly for something that is not going to really help you make knives faster (believe me it will SLOW you down considerably).

I like your unwillingness to believe what John Doe says, most of the Doe family is full of B.S. or only really care about information that will make great advertising. I don't want to be part of the Doe family so I need micrographs to give more than my say so to validate my positions. I would rather show you the pearlite colonies mixed in the martensite that was quenched in "secret soup", than just skate a file across it to prove it supreme and insist that you trust me and buy lots of my soup!

10xx series steels give us a very nice mechanism to tell if our quench speed is there, that would be that hamon they so readily make. Quenching a 1084 blade in any oil should produce a cloudy hamon somewhere on the blade, with no clay at all (very thin blades may not, but 3/16" or better at the spine will). Where that line is can tell you a lot about the quench speeds. Slower quenches will bring it closer to the edge and make it straighter (suguha) in nature; faster quenches will move it closer to the spine and more broken up along the top. The closer to the spine you can get it, the better, if you can make it disappear at the spine- GREAT! There are folks on this forum that attended my metallurgy lecture in Ohio last summer, and they will be able to tell you why it is good to keep that temper well away from that edge due to fine pearlite. I set up a scope there with a video feed and showed how far into the hardened zone pearlite will go.

Rockwell testing and breaking those samples to examine the end grain can also reveal plenty. The smoother and cleaner the break and inner surface are the better.

 

[Kevin R. Cashen]

Alan, Stacy give an excellent answer, but I would also add the things I mentioned in my reply to David. Troosite is a term often used in many older metallurgical texts but has been abandoned in recent years as it was determined to be either fine pearlite or bainite and not a phase unto itself. The vibrant whiter line at the top border of the hamon has revealed itself to me under the microscope to be higher concentrations of ejected cementite in sheets large enough to be seen.

 

[Alan Molstad]

The vibrant whiter line at the top border of the hamon has revealed itself to me under the microscope to be higher concentrations of ejected cementite in sheets large enough to be seen.

You know what...
Im more or less sure that if you had mixed up all the words in that sentence in a different order, I would still not be able to tell the difference....LOL

What I understand is this:
My plans are for next winter during my free time:, I plan to make a few mono-steel Japanese "Katana" swords.
My steel will be 1050 or 1060 or 1065, as the price of such steels change .

I want to end up with a very hard cutting edge, and yet a spine that will not chip or snap while I learn the art of cutting as part of my Kumdo or Kendo class.
As this is a sword I will be learning on, I want a sword that will be forgiving,,,I cant have a sword that will snap just because I pushed it over the limits in a errored cut.

From what Im hearing, I should be able to tell if I reached hardness in the quench along the cutting areas only by looking for a good hamon?
If I see a good clear hamon, then I can go ahead and finish the sword up?...

also, although in a short knife that I might make from ball bearing 52100 the term "hamon" might not apply, yet the acid etch still should show me if I need to Heat treat again or not......

Correct?.

 

[David Wesner]

I think I should first point out that we are all "we"..

Yes, I would include you in "we" too. I meant "we" as in opposed to "Admiral","Crucible","Kobe","Sandvik" etc., you are still the only "we" I know that has a Charpy C-Notch Impact tester

a file test, providing you realize its limitations, and just cutting on things is enough to let you know you are on track

I do, at least have a Rockwell tester, and I'm sorry to say, an unhealthy fetish for files, many many files . And also a pretty darn good microscope, whether it is the right type is another matter

My scopes are for research well above and beyond this, and are an important part of my arsenal in combating the B.S. that has thoroughly covered knifemaking. I believe Tim has a scope for much the same reasons.

I am asking the questions for the same reasons, so we're on the same page in that sense

I just got a rather expensive shipment of lapping and polishing equipment to be able to properly use my microscopes more, so let me say that it is not just a matter of getting the scope and going to it, it is quite involved and costly for something that is not going to really help you make knives faster (believe me it will SLOW you down considerably)

And that would have been my next question. How to prepare the "sample". It sounds to me like I may already have what "may" be needed. "May", being the key word here. I'm not looking for "faster" at this point in time. On the contrary, I'm looking for better, and more importantly, I'm looking for correct

I like your unwillingness to believe what John Doe says, most of the Doe family is full of B.S. or only really care about information that will make great advertising.

Thank You Sir, I have never fit into the "sheeple" category to well. I could go on "quoting you" and asking questions for a considerable amount of time but I'll give you a break, I know you're very busy too.You have, as usual when you post here, brought to mind, more questions than answers , ( by that I mean I have learned something, which, in itself raises more questions ) I have enough to "chew on" for a while. I will be back though , you can count on that. Thanks again

 

[Alan Molstad]

Tim Zowada, has a very good, very basic, heat treat article in the latest issue of "Blade". .

It might be a few days before I get around to going into town to see if the store has this issue of BLADE in stock yet.

Has anyone had a chance to read the article and got anything out of it?
Whats it say?

 

[Alan Molstad]

David, did you get a chance to catch the article yet, and what if anything did you find interesting within it?

 

[Alan Molstad]

1084 must be cooled from autenitizing to below 1000F. in less than a second to successfully harden, .

While an interesting 'fact' to know....how would this information ever change anything a knife maker does?

I plan to Heat-treat some 1060 steel one day. My guess is that the time needed to get that hard in the quench is about the same, give or take a few seconds correct?

But, so?

Once we dunk the blade in the quench tank, thats about all a guy can do to speed cooling,,,,blowing on the quench tank is not really going to help much ...

The speed it cools is the speed it cools... (Unless you guys know some tricks I have yet to hear about)
How would knowing that steel type "X" cools in 1 second to get hard, and steel type "Y" cools in 3 seconds, matter to us?,
Once it's in the quench tank thats about all there is to do....

 

[Phillip Patton]

While an interesting 'fact' to know....how would this information ever change anything a knife maker does?

I plan to Heat-treat some 1060 steel one day. My guess is that the time needed to get that hard in the quench is about the same, give or take a few seconds correct?

But, so?

Once we dunk the blade in the quench tank, thats about all a guy can do to speed cooling,,,,blowing on the quench tank is not really going to help much ...

The speed it cools is the speed it cools... (Unless you guys know some tricks I have yet to hear about)
How would knowing that steel type "X" cools in 1 second to get hard, and steel type "Y" cools in 3 seconds, matter to us?,
Once it's in the quench tank thats about all there is to do....

Alan,
This is important to know, so that we can choose which quenching oil to use, because they all cool the steel down at different speeds. Texaco type "A" would not be a good choice for quenching 1095, because it doesn't extract the heat quickly enough.
Water would not be a good choice for O1...
Good question.

 

[Matthew Gregory]

higher concentrations of ejected cementite in sheets large enough to be seen.

I call pull this same trick off, but my arm gets really tired after a while and I stop enjoying it.

Sorry, couldn't help it.

Alan, you can regulate how a steel will cool by utilizing proper quenching medium. Most people go under the thinking that what worked in the 'old days' was good enough, so they use ATF or veggie oil, etc. Simply by switching to REAL quenching oils -- oils designed and developed for this application, we can improve our results by an order of magnitude, and do it consistently. Does the number 1000 need to mean anything? Yes, if you know that the quenching oil you use can achieve it!

 

[Matthew Gregory]

RATS!

Phillip beat me to it!

I have to get one of your knives, btw, Phillip. LOVE your handles!

 

[Alan Molstad]

Alan,
Texaco type "A" would not be a good choice for quenching 1095,

Interesting, but I will be quenching the 1050 in water...

I use the Type "A" for my steels like 52100 and it seems to cool about right.
So far it has anyway as I get the lines on the sides of the blade from the acid etch that Im told now do show that that part of the blade was correctly hardened.

But then again, once it's in the water or in the oil, thats about all I do from then on...
Far as I know, once the steel is under the water or the oil or whatever, there are no ways to speed the quench given that you only had,,,what?...One second?

 

[Guy Thomas]

While an interesting 'fact' to know....how would this information ever change anything a knife maker does?

I plan to Heat-treat some 1060 steel one day. My guess is that the time needed to get that hard in the quench is about the same, give or take a few seconds correct?

But, so?

Once we dunk the blade in the quench tank, thats about all a guy can do to speed cooling,,,,blowing on the quench tank is not really going to help much ...

The speed it cools is the speed it cools... (Unless you guys know some tricks I have yet to hear about)
How would knowing that steel type "X" cools in 1 second to get hard, and steel type "Y" cools in 3 seconds, matter to us?,
Once it's in the quench tank thats about all there is to do....

Phillip and Matt covered things nicely I think. Here is another angle to "think" at it from. The steels we use are frequently classified in general categories(based on how quickly they need to be cooled) as water hardening, oil hardening and air hardening.

The simple 10XX steels need to be cooled very quickly (as in 1084 needing to be cooled to under 1000 degrees in less than a second) and are generally classified water hardening, but in the thin cross sections that knives have they often harden fine in oils especially if significant amounts of another alloying element such as manganese is present (see next paragraph!)

With the addition of alloying elements other than carbon the hardenability of a steel can be affected so that it hardens much more reliably. A steel like the aforementioned O1 or something like 5160 has much more time to get under it's pearlite "nose" temperature so a slower oil quench is used which also eases the shock of the quench. A fast quench in water on these steels could easily crack the blades to pieces from the stresses of the austenite to martensite transformation. As with the water hardening steels being able to harden in thin cross sections in oil, many oil hardening steels in thin cross sections can harden to a degree in air.

Add even more alloying elements, like the stainless steels, and you have steels that use atmospheric quenches (gases such as plain air or nitrogen). You have a hard time "not" hardening these steels! But on the flip side, because of these extra alloying elements, they require a much higher austenitizing temperature and a much longer soak time before quenching.

So you see, knowledge of how quickly a steel needs to be cooled is crucial to getting that steel to harden reliably in the proper quenching medium which is the crux of making a reliable blade.