Tripple quench, once and for all. Maybe

i could not get to swordforums :( but i am still somewhat confused. can someone tell me what temp to soak at and how long to soak at that temp to do a spheroidizing anneal, and also what temp each should be quenched from to produce the best grain structure for a blade.

steel , Temp and time to spherodize anneal , temp to quench from

1080

1095

5160

L6
 
terry.....I dont want to know...LOL

I forge down 5160 load shafts. it takes 3 or 4 days for me to do. Mete and kevin has convinced me that (given my limited understanding and tools to work with) Im going at it just fine.

I used to do a 3-quench heat-treatment. Then I started to test my work by the limited standards I have, and was unable to support the use of a 3-quench over a 1-quench heat treatment. ( I still end up doing a 3-quencher, but only by accident now)

Im happy....I dont want to know anymore facts,,,all them big words Mete and kevin use just give me a nose bleed anyway.

good luck my friend,,,,
 
I'm on at least my third reading of this thread and now I've got a few questions.

When triple edge quenching, you can see three hammon lines, often they overlap. Why aren't they 'erased' when overlapped by a later edge quench?

Kevin, you mentioned (more than once) that getting carbon back into solution from spheroidized anneal takes longer - practically speaking when forging a knife, how long, an extra 2 minutes at Ac1? 10 minutes?

What's anyones guess on those crystal lookin things on Ed Fowlers latest knife pic?

Exactly which Heat Treaters Guide is the one to get? There seems to be more than version.

Is it possible that on quench #1 and #2 of a triple quench, that increased points of nucleation have refined the grain and there for the cutting edge retention?

What is a 'mete'?

I've read more than one article that say the carbides are what cuts, the metal surrounding them just holds them there. What is actually doing the cutting? Does finer grain equate or at least relate to a finer distribution of carbides?

I gotta stop now and get a snack. I think that wore me out.
 
Tracy,

I told myself I wouldn't post on this thread again, but now I want to try and answer one of your questions. See how close I can get:

When triple edge quenching, you can see three hammon lines, often they overlap. Why aren't they 'erased' when overlapped by a later edge quench?
Click to expand...

(I'm running on the assumption we're talking forged 52100, which Ed says improves with 2 'normalizing' cycles prior to the final quench.)

If the first 2 'quenches' are in fact refining the grain structure and improving the blade performance, then the structure of the steel will be different for each succeeding cycle. And if etching brings out changes in structure(grain) and each quench is at a little different depth .... well then something should look different.

If the triple thing doesn't have any effect then I would expect 'erasing.'

Now if you had a steel that didn't need thermal cycling I would expect each quench would 'erase' the previous. For example, if I forged and then properly normalized 1084. Then triple quenched (each heat/quench identical to the previous one) I doubt you'd get the same visual effect.

Steve

How'd I do?


PS This is the definition I'm using for Normalizing:

Normalization

This heat treatment is performed to refine grain size and to obtain a carbide size and distribution that provides a favorable starting point for subsequent heat treatments; it is usually done to hypoeutectoid steels. It comprises austenitization at 100 to 150 °F above the Ac3 line followed by an air cool. This heat treatment is performed to refine grain size and to obtain a carbide size and distribution that provides a favorable starting point for subsequent heat treatments; it is usually done to hypoeutectoid steels. It comprises austenitization at 100 to 150 °F above the Ac3 line followed by an air cool.
Click to expand...

This is different than annealing in that you cool fast enough so the carbon doesn't pool up on ya.
 
Any triple quench steel will do that shows three hammons (etched or not). Ed's 52100 is as good an example as any.
I did make an assumption on this question that probably should be stated. I assumed a triple edge quench would be taken to Ac1 (I'm getting into these terms) for each quench. If the steel is taken to Ac1 with sufficient time for cabides to go into solution, shouldn't the crystalline border (hammon) dissappear if it is 'over lapped'?
Steve, you mention depth of quench as though it were visible to the naked eye. I'd think you can only see the surface of the steel or did you mean something I'm not catching?
Do 3 visible hammon lines offer evidence of 'improved' steel (performance?) over a single quench?
 
Tracy,

Thanks for asking for clarification. Make me think more.

(Again I'm just trying to express what I'm learning, not like I know!)

Let's say the steel in whole knife is in state A. Now you bring the whole thing up to Ac3 and edge quench. The spine is going to be normalized (air cooled style) and in state B1, the grain in the edge is going to be different. We'll call it B2. B2 = Martensite with smaller grain than state A.

Second quench: Now the spine is C1 and the edge is now C2. C2 = Martensite with smaller grain than state B2.

Third quench: Now the spine is in state D1 and the edge is D2. D2 = Martensite with smaller grain the C2.

B1, C1, and D1 are all what I'm famil1ar with in normalizing: 3 air cooled cycles for finer grain structure.

B2, C2, and D2 are 'evidently' even more refined (as claimed by the proponants) than their air cooled counter parts.

There will also be a zone between the spine and the edge with some B2, C2, and D2 grain structure. If the 'dip' was identical all 3 times zone wouldn't have much mix. But dipped by hand I'm sure you'd get all sorts of 'zones'.

Am I making any sense?

Steve
 
RE: Normalizing.

One of the papers I'm reading has experiments on the effects cooling rates on grain structure. It is really interesting

1018 changes a bit between furnance cooled (annealed) and air cooled.

4340 there's a HUGE! difference. No way I'd want to harden 4340 from an annealed state.

And what little I know each steel is going to be different and the condition of the steel prior to normalizing will have an effect.

Also, the cooling rate does have an impact.

Could it be that 52100 only reaches it maxium potental with a normalizing cooling rate that approaches quenching rates?

Maybe if you took a forged 52100 blade and normalized it twice with forced air, then one quench cycle you'd get the same results.

Steve
 
Tracy, you're slow . mete = metallurgical engineer. Let's go back a step. If we have a 1084,the eutectoid, we have only martensite which cuts very well. If we go above the eutectoid we have martensite + carbides. The carbides adding wear resistance. The grain size can be totally independant of the size and distribution of the carbides.One of the advantages ,in many ways, of Crucible's CPM steels is that the carbides are smaller and evenly distributed.You could mess things up and have carbides in prior grain boundaries.......Sando, you are using the metallurgists definition of normalizing.Yes the steel type makes a big difference .Air hardening grades ( also 4340 and others in thin sections) Can't be "normalized" since they will harden on air cooling . These types have to be annealed. ..... Three hamons - if we heat treated ( in my industrial experience) something and it warped we would do it again. If it warped again we would heat treat a third time . If it still warped it was scrap because we weren't sure what we had then .LOLLOL
 
Mete (eng)
I'm slow? There's a news flash. If I'm slow how come it's not 'meta' or 'met-eng'?:D
Your answer on the carbides makes more sense than what I (thought I) understood.
Do carbides, in some way, contribute to nucleation points? Excess carbides that can't be absorbed into the lattice -- do they have any affect on each other like attracting so they clump or repeling to they disperse? Since boundries attract 'junk', are these excess carbides normally found in grain boundries?

Steve, your example supports 3 quench is cumulative (and beneficial?) if each quench is actual progress towards smaller grain. I get what you are saying but why do the three hammon lines show if heating to Ac1 essentially wipes the slate clean?
 
Sorry Tracy I didn't answer that, did I? Heck maybe I don't understand enough to. but here we go.

why do the three hammon lines show if heating to Ac1 essentially wipes the slate clean?
Click to expand...

(I hope I'm getting this! mete or Kevin please clarify me on this.)

When you go back to Austenite you have wiped out the Martensite. That slate is clean.

However, you have not necessarily made a change in the grain size. Otherwise, Normalizing wouldn't matter! Everything I've read (and I don't understand the mechanics yet) state that the grain size prior to the hardening cycle matters.

Now you can stay above Ac3 long enough to increase grain size, right? That means that just crossing the austenite line doesn't instantly give small grain or large grain.

Logically, if when you did the triple quench but stayed for a hour or heated to 1700 degrees, you grain size would be big again. THAT would wipe out the effects of the first 2 'normalizing' cycles.

So, while the Martensite slate is clean, the grain size improvements are cummulative, to a point.

(This is all my understanding and if I'm right:)

In my example there are 3 different grain sizes within the martensite. B2, C2, and D2.

The hamon is developed (like film) in a zone where there is a mix martensite and plain old pearlite and the appearance of the hamon is effected by the grain size. It stands to reason, depending on where you quench, you'll get all sorts of effects.

-----------------------------------------
blah, blah, blah
-----------------------------------------
I'll try and shorten that:

Going into Austenite wipes out the martensite, but does not necessarily reset the grain size slate.

Steve
 
Mete,,,I don't know if you remember this or not, but at the start of this winter I posted a question about some "dots" that ended up on my blade.


I believe my old post was one of those that have been lost in the Forum change/mix-ups, however I have more to add to that topic.

What happend to that blade of mine, also happened to another one before I changed over to a different system. At that time I still believed that a 3-quench heat treatment was helping my work. And for this blade not only did I plan to do 3 quenchings, but I also did a little experiment.

What I did is during the forging (takes about 3 or 4 days) I did 9 different cold-oil quenches. I did 5 cold oil quenches after I had finished my last hitting of the steel with my hammer. I would heat the steel to the non-magnetic temperature, then took it outside and dunked the blade right down into a 4 foot long/6 inch wide pipe filled with Mineral oil.

It smokes!

Anyway the reason I'm telling you this is that, as you may remember, when I etched the blade I had weird "dots" in the blade. The dots were all along the cutting edge on both sides of the knife, and went up the side about 1/4 to 1/2 the way up.


I never was able to post a good photo of the dots, however I have just seen a photo on Blade forums that has the same dots that were on my blade.

http://www.bladeforums.com/forums/showthread.php?t=294129


I've got to tell you; unless my eyes are playing tricks on me, or my computer screen is in need of some windex, the photo of this knife has the very same type of dots that I had ended up with on two of mine....
 
Steve, now that makes sense, I was under the impression that grain would dissappear hand in hand as the steel slipped into a fully austenite state. Of course it doesn't since it grows when over heated or with a prolong heat above Ac1. You should be a met-eng. :p
 
DaQo'tah Forge said:
terry.....I dont want to know...LOL...

...Im happy....I dont want to know anymore facts,,,all them big words Mete and kevin use just give me a nose bleed anyway.

good luck my friend,,,,
Click to expand...


You are probably onto something here, there are days I wished I could unlearn things. :) Things were so much easier for me when all I had to do was forge it, grind it, heat treat it, and then sell it or use it. ;)
 
tmickley said:
I'm on at least my third reading of this thread and now I've got a few questions.

Kevin, you mentioned (more than once) that getting carbon back into solution from spheroidized anneal takes longer - practically speaking when forging a knife, how long, an extra 2 minutes at Ac1? 10 minutes?...

...Exactly which Heat Treaters Guide is the one to get? There seems to be more than version...
Click to expand...

I noticed today that I still had tension and regrets from the way I handled this thread, so I have went back and done some editing to try to clean up my act and clear my conscience (I have saved copies of the originals to avoid ducking my responsibilities or appearing dishonest).

Tim, I will be happy to offer any information that I have on the simple, helpful questions. I will decline the ones that may lead to hard feelings, until I can control myself better. Nothing makes me feel better about myself than being able to help out with such questions.

Your first question is a fairly tough one. There are more variables than you can imagine, so there are almost as many answers. My ongoing testing has shown that my L6, from one of my spheroidal anneals, requires at least 4 to 4.5 minutes after recovery, in salts, to reach the top of the curve in HRC (in thickness of .125” to .250”). This is in salts, which can be one of the quickest ways to heat, I cannot accurately guess how long it takes in an open air oven, or forge, except to say that recovery times are typically longer in such environments.

The best way to determine this really is to make up a series of test specimens and start quenching them at timed interavls with the equipment that you will be using. I am pretty sure that somebody elses steel done in other salt baths would have slightly different times (pretty darned close, but still a bit different. If you are not planning on heavy machining, and are working with simpler steels that have carbon levels closer to .8%, I wouldn't even worry about those little spheres. Pearlite is soft enough for a grinder and will go into solution quite easily. In fact I sometimes wonder if I would get more life from my zirconia belts if I did the lameller (pearlite) thing instead of spehroidizing.

The newest, and most expensive, version will have all the bells and whistles, as far as tons of explanitory and how to information. But if you just want the good stuff (the technical info and specs on every steel) I suggest and earlier edition with the lower price tag. Mine is from 1982 and cost me less than $50.
 
tmickley said:
...If the steel is taken to Ac1 with sufficient time for cabides to go into solution...
Click to expand...

Hey Tim, you are starting to get the hang of this, but...
Ac1 is the temp at which the transformation will first begin. From there up the carbides will gradually, but incrementally, go more into solution. Acm is the temp you shoot for to get all the cementite (iron carbide) into solution. Other elements can complicate things, however. Vanadium, for example, is and increadibly strong carbide former and will require more effort to break its bonds with the carbon. That is one of the reasons that steel wtih lots of vanadium will resist grain growth better.

Another note- Ac3 is the temperature you go to in steels with less than .8% carbon in which case you need to disolve the extra ferrite.
 
Tracy , my degree is abreviated BS Met E, you may take that any way you want. There is a very important distinction with carbides whether it is a eutectoid or hypereutectoid steel .With the eutectoid you will dissolve all the carbide no matter what, though spheroidized will take longer. As carbon content of the steel increases more and more of the carbides remain undissolved. The size and distribution of the carbides has much to do with the original processing of the steel especially solidification problems. Only some of that can be corrected at the higher temperatures of forging.The CPM steels solidify very differently and thus produce those fine evenly distributed carbides which make things better for grinding , machining and performance.BTW each of the types of carbides grinds differently , iron carbide and chromium carbide are fairly easy to grind.And as Kevin has said ease of dissolving is also different for each of the types of carbide.
 
Kevin, I was kinda hoping to get a grade on my essay answer.

Is it the combination of pearlite and martensite that makes for a hamon? Is it the variance in grain size? Both?

You see I don't know exactly what kind of steel structure it takes to make the white hamon via the Hadori finish.

Steve
 
Sando said:
Kevin, I was kinda hoping to get a grade on my essay answer.

Is it the combination of pearlite and martensite that makes for a hamon? Is it the variance in grain size? Both?

You see I don't know exactly what kind of steel structure it takes to make the white hamon via the Hadori finish.

Steve
Click to expand...

There have been so many comments on the subject I am not sure I follow you as to what part of which previous post you are talking about. Simply put you are going to get pearlite or martensite with a transition zone that could have degrees of ferrite or cementite. Japanese hamons seem to look "cleaner" to me than some of the American stuff that is resulting from carbide segregation. This is because it is a simpler effect. Tamahagane is shallow hardening so it is closer to a pure pearlite to martensite thing.

Much of our steel will behave differently. Steels with excess cementite or carbide forming alloys that are treated with various soak times take on different appearences because of the carbides and alloys banding. I get it with O1 a lot. And there is an infamous image of overcycled 52100 floating around the internet with my intials imprinted in the pseudo wootzy pattern. One good heat to Acm will get you back to good as new though.

Either way I would have to say that grain size plays a much smaller role, since the parent austenite grain boundaries are what they are, regardless of the microstructure within them. Martensite always appears finer because of its acicular (needlelike) nature and the way it reflects light at different angles.

I hope this helps. I hope I understood the question.
 
Kevin,

Actually that does help! I was refering to my post number 110. Which was trying to address Tracy's question about why a triple quench produces 3 hamons. Sounds like I wasn't too close.

Could it be that it requires each 'dip' to be more shallow than the previous.

In any case you've given me more thoughts and terms to study --- geee thanks ;)

Steve
 
I would like to say that I have found this post to be one of the most interesting I have ever seen on Blade Forums. I have learned from those who favor the tripple quench, and also from those who don't see any reason for it to work.
I am somewhat skeptical about the tripple quench but since I have not ever tried it I intend to keep a open mind. I have some 5200 steel from Rex Walter (It is very expensive), and some Texaco type A quenching oil.
As soon as I get caught up I intend to test single quenched and tripple quenched blades and see what kind of results I get.
I really don't understand why anyone should get upset if they are questioned about their techniques. A hundred years from now how I heat treat my blades will not be very importaint. Sometimes it takes losing a friend in a car accident, or ones wife coming down with cancer to really show us where our priorities should be.
I really appreciate Kevin and Metes sharing of their information as well as those who favor the tripple quench sharing their methods.
At the risk of upsetting someone I would like to ask this question. How many tripple quenched blades have won ABS cutting contests? I don't know. If I did I would not be asking this question.
At the last Blade Show in Atlanta I watched the five finalists compete for the ABS championship. Please correct me if I am wrong but one blade was damascus, one was 52100 (which by the way chipped on the first cutting contest and was thuss disqualified), I think two others were of 1084, and I don't remember what the other one was made of. Were any of those five blades tripple quenched? I don't know the answer, maybe some one else does.
I also know that one of the five finalist was Kevin Cashen. That shows me that he knows how to heat treat.
One more question, would L6 be a good steel to try the triple quench with, or should I stick to 52100?
Again, I appreciate everyones willingness to share information and hope I have not offended anyone with my questions. I think we would all agree that we want to make the best knife possible regardless of how involved the heat treating process might be.
 
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