Tripple quench, once and for all. Maybe

Mete,

to answer your questions.

1. I was unshure of the state of the steel I was using. It was given to me by Wayne Goddard and I didn't get a spec sheet with it. It was harder to cut than some other L6 that I had so I took it upon myself to do the sherodizing. I did this cycle twice because that is the way that I do all of my steel.

2. I don't remember the exact working temperature of my oil. I do remember that 165 was within these limits and the slightly higher temp showed us some improvements in the number of cuts we could get on our unscientific rope cutting. I don't go higher than that because when I quench a large blade or multiple blades then I can't keep the temp of the oil below my personal comfort level.

Now it is your turn.

1. How could multiple spherodizeing cycles harm the steel? Everyone posting on this thread is lamenting the use of multiple thermal cycles. Is a spherodizing heat not a thermal cycle?

2. At what point in time did the "medical establishment" become a scientific entity? It must have been after 1928 since here:

"The medical 'establishment' has always been reactionary. It's the all too common "I never heard of it therefore it doesn't exist" syndrome.They never tested his ideas scientifically ,they just rejected them.It was the lack of science that held back these people and their ideas."
you seem to think that it was lacking in science. And are you not saying something of the same thing about the triple quench?

3. " the type of quenchant and it's characteristics are the most important, small differences in temperature won't make that much difference. "
Is the 25 degrees between 140 and 165 a small difference or a large one?

4. You never answered me when I asked;

what should I do to make a single quench seemingly perform better in my totally unscientific tests?

Kevin,

I was not trying to bring this tread down or put words into your mouth. I was just trying to point out to you that what you were saying could be taken in the wrong context. It was very clear to me that you were using the bigfoot thing as an analogy. If you will reread what I said from a neutral corner:

"Kevin you seem to believe that I am making this stuff up and spreading rash comments and half truths around. You also seemed to have missed the fact that I posted exactly what steps I took, how I did them and what steel I used and I'm not sure but It seems that you think I saw big foot. :eek: "

I hope that you will see that I stared off by saying; "you SEEM" And ended it with an atempt at humor. I hope that you see it that way now.


" I saw the exact steps that you posted and I can see where I would have drawn entirely different conclusions."

Please tell me so that I can compare your conclusions to mine.

"It has been fairly common for me to encounter bladesmiths who try to use science to support their conclusions, but when they are faced with the fact that scientific principals do not support their ideas, they reject science as flawed. I have seen your exact argument many times before, the problem is it is not a preference type of thing. The laws of physics do not have an on/off switch for when they are convenient for our positions. We started out wholey embracing a scientific method to prove or disprove this thing. Now science is fading to the level of medieval mystics."

Tell me how I have said anything about science being flawed. Or that there is anything mystical about the methods that I used. Tell me, have you done a similar test? What were your results? Are you saying that the science of metalurgy has advanced as far as it can and that there are no other ways to improve upon current industry standards? That there is no need for you to do this kind of testing beacause industry and science says that there is no room for improvement. Are you really willing to accept this as written in stone? If you are then you are right I have missjudged you.

"What about Galileo, don’t forget Galileo, he was really mistreated and imprisoned for his radical ideas. Da Vinci , Galileo and, I daresay, even Columbus and Orville and Wilbur, were the scientists of their time. It was the superstitious, unenlightened, medieval minded people of their time, not science, that scoffed at these men that used logic, reason, and disciplined methods of observation based on established principals, to achieve their goals. If quenching 3 times can approach the achievements of these men, then what are we waiting for?"

I have to say that I believe that you are totally off base here. These great men although scientific and science minded were not the scientist of their time. They were not using science or the established principles of science. They were using disiplined methods to ESTABLISH the principles of science and scientific practices. The scientist of their time were the superstitious, unenlightend people they were trying to disprove. I do not remeber the Wright brothers as being aviation scientist. No I remember being taught that they were a couple of guys running a bycicle shope who thought that if they put a motor on a glider that they could have powered flight and the aviation science of the day telling them that it was impossible. I am not even trying to imply that what I am doing compare to these mens acheivements I am trying to point out that science is a continuem and what was once an accepted fact can and has been proven wrong. will I or any one else ever to be able to prove the triple quench beyond argument? I seriously doubt it. Have I proven that there are instances where it is better I believe so.

"I have not said that I have some undiscloseble practices that I cannot tell of but that they make phenominal knives when I can repeat them…
But can you use your mystery techniques to harden it to 58 - 60 hrc and then bend it all day without having it break?"

These two lines would be most offensive, if you knew me, but since this is the first we have communicated, I must let them pass without any hard feelings. Anybody who knows me knows that I passionately DESPISE secrets and that all of my shop practices are an open book. I will tell you any part of my procedure without reservation. I have no undisclosed or mystery practices. What I refuse to tell people are some results I have gotten in testing the product of those practices. That’s right, I have been very pleasantly surprised with some of my performance tests and I refuse to boast of them! I feel I have a responsibility to verify those results completely before making statements about the performance of my blades, that I cannot explain. Even then, I will still let the customer decide. It is, after all, just steel, just well heat treated steel. If I tried to keep my techniques a secret, one trip to the library would blow me out of the water."

When you quoted me above you left out the most important part of the paragraph. It should have read like this;

I have not said that I have some undiscloseble practices that I cannot tell of but that they make phenominal knives when I can repeat them.... But can you use your mystery techniques to harden it to 58 - 60 hrc and then bend it all day without having it break? Comparing unhardenable mild steel to hardend L6 is no more fair than me asking the last question.

With the last sentence put back into context I think that it shows that I am not trying to offend you but simply pointing out that your comparison of mild steel to hardend L6 is as unfair as me saying that you have a mysterious undisclousable unrepeateble technique.

Kevin I am not offended and do not wish to make an enemy of you or to offend you in any way. I am not saying that the triple quench is the perfect solution to every kind of steel or that if a person does only a single quench that they are not doing all that they can do for the steel that they use. I am saying that with my practices in my shop that I get better results with the triple quench. I am willing to try different methods but I am going to compare my perceived results for the new method to what has given me the best results up to that point. If you tell me that if I treat steel xyz to the bfd and then give it a single quench it will be better than xyz given the bfd and a triple quench and it proves to be the case then I will do it that way. But if I can give xyz steel the fubar treatment and a triple quench and get better results with my tests than I did with xyz to the bfd and a single quench then I am going to give it the triple treatment every time. And this could go on and on that is the one thing in this whole thread that is for sure.

I am not going to reply to this thread again until after the OKCA show this month because it is taking up too much of my time and Taking my mind off of what I am doing. The floor is yours. Please keep in mind that I am only trying to make a point and not trying insult, ridicule or put down anyone.
 
As a general comment to all my basic reason for being on this forum is to teach metallurgy.I am a practical, logical type and it seems to me that if a person is heat treating on a regular basis he should know something about metallurgy.I have a problem when I ask 'why do you do it that way' and get the response 'I don't know ' or 'because Mr X does it that way'. There was arecent posting on swordforum where someone tried to heat treat stainless steel as if it were 1080, it didn't get hard ! No kidding ! .......The medical profession talks about the 'science of medicine ' but all too often is not scientific. But that's for a different forum.......I'm not sure what might occur with multiple spheroidizing ,I never did it but possibly large grains and large carbides.......140 to 165F is not very significant for oil .......I'm not in a position to comment on knife tests though they are accepted in the field .However to be scientific they they should always be done exactly the same for all the variables.If you are cutting rope for example the characteristics of the steel are a factor but so is the shape of the cutting edge.......Both Kevin and I are trying to take the myth out of heat treating, we are not here to attack people and often our comments are to the general audience rather than the specific post.
 
Mete...

You have helped me a lot.
You have put some science behind what I have started to find true in my own limited testing.
_________________________________
Although cutting is what each knife is made to do, a cutting test is not something that seems to me to be a very good test of heat-treatments.
There just are way too many things that can effect the way one knife cuts over another.

If some guy asks me why does knife (A) seem to out cut knife (B) ?
I would have to say that there just is no way to know why this is true, or even if this really is true.

A better head-to-head test of different heat-treatments might be a test where you were testing the steel only, and not accidently be testing the grind, the angle of the edge, and the sharpness of the cutting edge. You should not even need to sharpen the knives if you really were searching for answers.

The answer must be in the steel in some way, sharpened or not.


I guess that would be the question I would ask of you guys :

Can you point to some proof that you have found a good heat-treatment system, Without sharpening the steel?
 
Hi

I thought I'd "politely" add my $.02 to this thread. As I am a physician ( orthopedic surgeon) I believe I can comment on some of the medical analogies people are using.
1. Medicine has gotten more "scientific" and "evidence based" as the years go by, and in fact these are the current "buzzwords"
2. Any honest MD will tell you that the more we learn, the more we learn that we don't know as well. That doesn't make medicine "unscientific" but underscores the need to continue searching for answers.
3. None of the above changes the fact that there are certain immutable laws of science that cannot be changed be mere mortals


Which brings me to my next topic:

I have met Kevin Cashen @ several Ashokan seminars and I can personally attest to the fact that he is very knowledgeable about all aspects of metallurgy and quite "scientific" He is also extremely honest and straight forward, no BS, but very approachable and helpful to even rank newbies. He does not "keep secrets" in any way, nor is he anything but polite to anyone.

having said that, I commend you, Burke, for your efforts at looking into your methods of Heat Treating - intellectual curiosity is never bad. I think you and Kevin don't disagree as much as come at things from different directions. If you want to be more "scientific" let me propose the following experiment. In medicine, the gold standard is a "double blind,placebo controlled study" whereby neither the "treater" (MD) nor "subject" (patient) knows which variable is which until the experiment is over - this decreases unintentional bias.
so, Burke, get some new L6 , say 3/16" and cut the bar into 2 pieces say 6" long. Form them into identical(as near as you can) cutters- not knives, but beveled, zero edge bars like blades in power planers. (easier to keep identical)Treat one with a single and one with a triple quench after doing evrything else the same. Label one A and one B and send them to someone who can do cutting and bending tests WITHOUT knowing which is which, and have them post results only as A and B, letting someone else know before the test which is A and which is B but having nothing to do with the test itself.
This is not foolproof - particularly it is only one test and really should be replicated by different testers across different times, but at least it's a start. Sorry for being long winded, but I think this could at least spark a useful discussion. (maybe Spyderco would let you use their CATRA to eliminate some variabilty in cutting)
 
Kevin R. Cashen said:
I hear what you are saying Tim, but this is the second time that added cost has been given a plausible reason for the absence of such techniques in industry. Are we really thinking this through folks? Mr. Burke states 35 cuts versus 160 cuts in performance increase… does anybody really believe that industry would ignore a 350% increase in performance for any price? With those kind of results the standard operating procedure would be 3 times for everything and human sacrifice wouldn’t be too high a price for some to bury all the competition in the tool making market. For 20% I can believe manufacturing would cheap out and say it is not worth it. But for the kind of results that are often cited I know I would be willing to pay a higher price to buy one steel item that would out-perform like that.
Click to expand...
I don't know much about metalurgy - which is what this is about folks - but I know about business, and there is 0 doubt in my mind that if there was a process to make tools better, people would use it. If the added cost were very high, then it would be a small market, but there's always a market - however small - for a better product. In this case, the added cost would be minimal. HT is a very automatized process in tool making, and a tiny portion of the overall cost. Most of the cost of, say, a good quality file is around distribution, raw material, inventory holding, quality control, etc. Those wouldn't change.
 
I must confess that I took a day away from this thread to step back and assess what the heck I am doing here. My reputation is not being helped if every time I post, people go on the defensive and the tension level of the forum rises. I am tired of being dragged into confrontation every time I am tempted into a thread that I feel needs a balancing viewpoint, by now I must be looking like quite the jerk to many on Bladeforums. Believe me, in person, I am very non-confrontational and shy. Approaching conversations from a logical and analytical perspective has been very successful and friendly on other forums, but seems to get me in trouble here. This really puzzles me because this appears to be the most friendly and cordial forum that I now frequent. Unfortunately, on the internet, turning the other cheek can appear to be weakness or conceding to the other side. I will just have to take one on the chin here as I try to cleanse the confrontational subject matter from my future posts. I apologize to all present for the unease that my poor communication skills may have caused.

I will try to reintroduce my position in a kinder, gentler fashion.

Triple quenching is obviously a controversial topic, controversy by its very nature spawns debate. If we can all agree that this is another method of thermal cycling, a practice that most bladesmiths utilize in one form or another, then my points can stop here. We are all doing our own thing and liking it- peace be with you.

If one of us claims that he is getting 10% or 20 % improvement from some changes he made in his practices, I am sure all of us can just say “cool!”, and seeing the knife cut well is proof enough.

If one of us claims that he is getting 200% or 300% improvement over that which achieved from standard practices, it is not reasonable and logical that we ask for a proportional amount of proof or verification of those claims? Simply put, in the words of Carl Sagan, “Extraordinary claims require extraordinary proof.”

Websters Universal Encyclopedic Dictionary- “ extraordinary, 1a: going beyond what is usual, regular, or customary. b: exceptional to a very marked extent.

Nowhere does it infer false, untrue, dishonest, nuts, wacky etc…, so let’s all get more comfortable with the word, if we can. I think I am speaking rationally and reasonably when I say that, in the 21st century, cutting ropes and bending blades in our back yard falls far short of extraordinary proof, or evidence.

This thread seemed fine until, I asked for a reasonable explanation of this phenomena and some evidence to back up the findings. Then I felt like I had stepped on some very sore toes. I am I to assume that this topic is above and beyond question? I hope not, because as soon as we have reached that point, we are back to slapping Galileo in irons and hauling him away. You see, it was religious fanatics bent on maintaining their unquestioned beliefs that locked him up. Scientific method encourages questions and demands that you attempt to prove your theories. The previous fanatical approach forbids you from even trying to prove your conclusions. Several times in this thread I have all but begged that folks explain and prove these conclusions. It has only resulted in defensiveness.

As I previously said, the triple quench concept has often had an unchallenged platform in the knifemaking circle. Since many of it’s claims rest outside established, mainstream metallurgical thinking, why should it be unreasonable or unfriendly to give another viewpoint and ask for an explanation why traditional wisdom could be wrong? It must have something going for it, for so many folks to believe in it so strongly, so how can it be threatened by questioning and scrutiny? How can people knowing all view points be anything but good?

Mr. Burke, I had another post prepared that addressed your process step by step, as you requested, but that route was only leading to greater tensions and defensiveness, robbing this thread of it’s cordial nature. After reading your last post I realize that it really would be pointless, as you are firmly entrenched in your position and happy to be there, why should I try to mess with that? It would be counter productive to my attempts at being a kinder, gentler Kevin.

Now I think I will answer some of the friendly natured questions the best that I can. :)
 
BillF

My .02 worth

Now we are talking!
Thats sure sounds like the kind of test that could bring more information to us.

However after you do the first quench on both test sections of steel, you would need to place them in a covered box and then reach in and draw out one without knowning before hand the one that will get the 2 more heat-treatments.

I worry that if you know from the start what one will be getting only the 1st quench only and what one gets the 3 quenchings, that this might effect how well you do that first quenching for both of them.

If you did not know what section of steel would get what type of heat-treatment, you would try very hard to make both as good and the same as you could...

____________________

Another test that I would like to see at a BLADE show is for the guy who supports a 3 quenching and a guy who supports a 1 quenching, to both be given a section of steel cut from the same leaf spring.

Let them do whatever they want to the steel they are given..heat-treat it in all the different and secret ways they can think of ..and in the end just hand the steel back to METE and ask him to find any differences if he can without knowing what steel came from what system.
 
DaQo'tah Forge said:
Kevin.

I wrote to a more experienced blade smith last year about his heat-treatments and he told me about this quenching during the forging that you listed as something you tried.

Can you tell me about this? I have been thinking about what use this would be? And if it did help at all, how it should be best done?

I forge John Deere Load shafts (5160) and it takes me about 3 days of work to get the steel flat enough and into the shape I need it to be in before I ever think about now Normalizing and annealing it. Along the way to that point, I will do my last heating of the session and then get the blade red hot, then just turn off the forge and allow the blade to cool inside it. Is there not a better chance of a crack to form if I suddenly plunged the hot blade into a bucket of oil during the forging process?

I actually did do a "Hot from the forge and into cold oil quench" on a few blades, but I had one crack, and another got weird spots along the sides from something so I gave it up.

Is there any advantage to a forging quench?
Click to expand...


I know there are some bladesmiths that frequently quench during the forging process, I do things slightly differently but will use quenching for grain refinement when I really need it while normalizing at the end of forging.

It all has to do with recrystalization. If one treats every forging heat as a thermal treatment, they will do just fine. Every time you reach Ac1 (start of recrystalization) with a piece of steel new austenite grains will nucleate within points of higher stored energy (strain), commonly at the prior austenite grain boundaries. These embryonic grains will be quite fine and will continue to develop as you heat to Acm (in steels above .8% C). At Acm, for any given steel, you will have dissolved all the proeutectoid (extra) cementite and you will have complete austenite solution. With no material left at the grain boundaries to use up, if heating continues, the grains will begin to feed on each other and start to grow much larger, this is the dreaded grain growth.

If one keeps the temp below the grain growth point and then cools the steel to a point at which austenite decomposes into a more stable structure, it will lock in the previous austenite grain boundaries with the new microstructure. Any new structures will be in alpha iron (BCC) which is more expansive, this will cause strain energy and many places of irregularity to drive fresh nucleation on the next heat. So if the process is repeated even finer grains can be achieved by working within that previous framework.

Normalizing is most often used to get an even grain size, but we can also use the technique to reduce grain size, by adjusting our temperatures and playing with the recrystalization process. If strain, or stress, for a more general term, is the driving force for recrystalization then we can ask ourselves, “what is the most stressful state of steel possible?” The answer is easy,- alpha (untempered) martensite. Steel can literally come apart of left in this kind of stress. So a quench can produce many more points of nucleation, more evenly, for the next heat than many other treatments.

I may get in trouble here but I will venture to estimate that one quench to Mf is equal to two or three low temp normalizations. I have some charts somewhere that shows some metallurgical tests to support this, but I cannot remember what text they are in and it is driving me crazy!

Now there are some cons to every pro, so I will have to let you down a bit here. It is very possible to get too fine a grain. The same thing that drives austenite formation also drives pearlite formation, so if you get your grain too fine, hardenability will take a nose dive as it will get increasingly harder to avoid pearlite in the quench. The other drawback is that all things have there limits, everything in the universe has its tradeoffs. The finer the grain size the lower the grain coarsening temperature, so after a few of these cycles it will be harder and harder to keep the grain fine.

If you had a crack from quenching a forging in 5160 (a very forgiving steel) you probably quenched from too large a grain size with many uneven sizes from the forging process. Larger grains harden deeper and develop higher stresses and uneven grain size is death for low stress/ low distortion quenching. I never quench until I have normalized at least once to a proper recrystalization temperature to equalize the grain structure.

Due to the amount of time, that you describe, to forge your load shafts down, I would highly recommend a plenty of normalizing at the end of the forging process. The more time you heat the steel, the more chances for things to go wrong or get irregular and non-uniform.

I hope this helps.
 
mete said:
As a general comment to all my basic reason for being on this forum is to teach metallurgy.I am a practical, logical type and it seems to me that if a person is heat treating on a regular basis he should know something about metallurgy.I have a problem when I ask 'why do you do it that way' and get the response 'I don't know ' or 'because Mr X does it that way'. There was arecent posting on swordforum where someone tried to heat treat stainless steel as if it were 1080, it didn't get hard ! No kidding ! .......The medical profession talks about the 'science of medicine ' but all too often is not scientific. But that's for a different forum.......I'm not sure what might occur with multiple spheroidizing ,I never did it but possibly large grains and large carbides.......140 to 165F is not very significant for oil .......I'm not in a position to comment on knife tests though they are accepted in the field .However to be scientific they they should always be done exactly the same for all the variables.If you are cutting rope for example the characteristics of the steel are a factor but so is the shape of the cutting edge.......Both Kevin and I are trying to take the myth out of heat treating, we are not here to attack people and often our comments are to the general audience rather than the specific post.
Click to expand...

I feel you have spoke very well for both of us here mete. I will let you be the mean guy, people seem to take it from you much better. The blade business seems to be doomed to taking one step forward and two steps back, because we are all far too willing to except information and claims without question or requiring verification. I really can't say it enough- it is always more important to question the anwers than it is to answer the questions!
 
billf said:
Hi

I thought I'd "politely" add my $.02 to this thread. As I am a physician ( orthopedic surgeon) I believe I can comment on some of the medical analogies people are using.
1. Medicine has gotten more "scientific" and "evidence based" as the years go by, and in fact these are the current "buzzwords"
2. Any honest MD will tell you that the more we learn, the more we learn that we don't know as well. That doesn't make medicine "unscientific" but underscores the need to continue searching for answers.
3. None of the above changes the fact that there are certain immutable laws of science that cannot be changed be mere mortals


Which brings me to my next topic:

I have met Kevin Cashen @ several Ashokan seminars and I can personally attest to the fact that he is very knowledgeable about all aspects of metallurgy and quite "scientific" He is also extremely honest and straight forward, no BS, but very approachable and helpful to even rank newbies. He does not "keep secrets" in any way, nor is he anything but polite to anyone.
Click to expand...

Wow! Thank you for the kind words sir. The Ashokan seminar is a great place to get to know the "real me". When asked to give my input, I will try to do it as unflinchingly yet as good hearted as possible. I make it a rule to always have multiple credibly established sources to back up any statements that I make. I enjoy folks asking me as many interesting questions that they can to spur stimulating conversation. If I feel paaions are too high I will simply find something better to talk about.

Speaking of Ashokan, I have been asked to take a more managerial part this year ( I am tired of boring you folks with egg head metallugy) so any input on what sort of demos you folks would like to see would be greatly appreciated and even influential. Ashokan is even more democratic than before!
 
Joss said:
In this case, the added cost would be minimal. HT is a very automatized process in tool making, and a tiny portion of the overall cost. Most of the cost of, say, a good quality file is around distribution, raw material, inventory holding, quality control, etc. Those wouldn't change.
Click to expand...

Those were my thoughts Joss. It seems very little to just pick those parts up and dump them back on the conveyor for another run. Aerospace and other industries are willing to incurr huge costs for much less gain than this, when it is critical to have a superior part.
 
DaQo'tah

you are quite correct about randomizing which steel gets the additional 2 quenches in my scenario - that would remove another potential bias. Also, each quench would have to be a complete quench - no edge quench where you might see different hardening lines which could give away the triple quencher. Also, tempering would be full - no differential tempering which is impossible to do exactly the same twice!
 
I have avoided posting this for a while now, but Kevin brought the subject up above, so here is some input on deformation of materials. I am not a metallurgist, but am a scientist trained in deformation of materials.

The term stress represents force applied to a material. Any deformation resulting from force applied is called strain. Stress cannot be built up in a material. Strain at certain locations may apply stress, but these are strain effects as in various dislocations that may initiate different directions of crystallization, i.e. grain boundaries.

Grain boundaries in a simple system would completely dissappear during thermal recrystallization, but in a system like (FeC) steel during recrystallization (Austinitizing), the diffusing material, Carbon, will tend to be trapped by the former grain boundaries and institute new boundaries/crystals in the same location.

If the new grains are subject to further heating, the stress applied works with increased thermal mobility of the grain boundary to create larger and larger grains. The amount of impurities (alloying elements?) in the system will work against the enlargment until they are liberated from the old grain boundaries and diffuse through the system, hence the greater soak time for more complex alloys.

These type of threads force me to review things that I learned working with minerals in reference to metals that have some different properties, but more similarities and are very helpful in furthering my understanding of the effects of heat treating steel.
 
kevin...


Good post, thanyou for the answer,,,,it does help me a lot.

However there was one of your paragraphs that I didnt actually understand, and it's kinda key to the whole post.

Could you break down this paragraph into smaller words,,,,,real small words....

so I can look at the tools I got, and see how to put what you are talking about into play?

(here is the part I didnt catch)
_______________________________


"If one keeps the temp below the grain growth point and then cools the steel to a point at which austenite decomposes into a more stable structure, it will lock in the previous austenite grain boundaries with the new microstructure. Any new structures will be in alpha iron (BCC) which is more expansive, this will cause strain energy and many places of irregularity to drive fresh nucleation on the next heat. So if the process is repeated even finer grains can be achieved by working within that previous framework."
_________________________________
 
Mr. Cashen and mete i really do appreciate you trying to explain the process involved to me. but i was wondering if you could give a step by step example of your opinion including soak times and temps of how to get the best blade i can from 1080, 1095, 5160 and L6 steels? how should we go about getting the steel we order (or salvage) into the best possible starting state, as well as getting it ready for the final quench? I am just curious where there may be differences in how some of us are doing it now.
 
Ok guys let's get it straight, that's at least twice in one page I see it wrong, it's spelled metallurgy !! ......The last time I checked into nucleation research the metallurgist stated that there were still many thing that they didn't know about nucleation. If we take a saturated solution of a salt in water and slowly let the water evaporate we will grow salt crystals.But if we start with absolutely pure water and salt we have a problem - it doesn't want to crystallize. It turns out that the crystals want some impurity to nucleate the crystal , a bit of dust or something. In metals the "impurity" is often found in the grain boundary because there is more space for things to collect.If we add boron in amounts of only .005% to steels this will greatly increase the ability to transform to martensite starting at the grain boudaries.Grain boundaries collect "junk" ( like phosphorous) also and between that and carbides in the grain boundaries we can get a situation where we can get a fracture at a prior grain boundary. This can often be the case in overheated steel, so our prior sins (over heating )can come back to haunt us......So what Kevin is basically saying is that on first time cooling the transformation starts at the grain boundary. The transformation to ferrite involves strain energy and the points of high strain energy are nucleation points for transformation to austenite on the next heating, meaning more austenite grains than in the original structure.....I hope that's what Kevin said.
 
mete said:
..So what Kevin is basically saying is that on first time cooling the transformation starts at the grain boundary. The transformation to ferrite involves strain energy and the points of high strain energy are nucleation points for transformation to austenite on the next heating, meaning more austenite grains than in the original structure.....I hope that's what Kevin said.
Click to expand...

What I actually meant was that I use my magical aura energy to charge my hammer with positive forces in order to increase the atomic density of the iron directly under the hammer blow, thus nucleating all new super-allotropic structures that are much finer than the mechanisms resulting in recrystalization, essentially halting halting grain growth on a sub atomic level :D :p ;) What else could I have meant?
 
shgeo, you are correct in pointing out that I should have labled "stress' as a less accurate or inaccurate term for what I was trying to describe. I may have been projecting myself onto the material since it seemsthat I have "stress" on my mind all the time these days.

shgeo said:
I have avoided posting this for a while now, but Kevin brought the subject up above, so here is some input on deformation of materials. I am not a metalurgist, but am a scientist trained in deformation of materials.
Click to expand...

Deformation of materials! Great! Perhaps in reading this thread you noticed some glaring inconsistencies/contradictions dealing with plastic deformation that are hard to ignore, but I am refraining from because I just don’t need the hassle?
 
Mete, sorry for misspelling metallurgist.

Kevin, my education was in deformation of minerals and rocks. I am able to go back to books and pull out stuff that was only peripheral to what I was doing then. There are two books that I labor through occasionally when trying to get around some of these concepts.

Stess and Strain by W.D. Means
Creep of Crystals by Jean-Paul Poirier

The Means book is a great intro to deformation. Poirier is a metallurgist and the book covers high temperature deformation mechanisms in metals, ceramics and minerals.
 
shgeo said:
...
Stess and Strain by W.D. Means
Creep of Crystals by Jean-Paul Poirier
...
Click to expand...
I can say with a great deal of certainty that these are two books I won't be running out to pick up in the immediate future but they would look good on my bookshelf. My head is still reeling from when Kevin threw Cementite into the mix. No one talks about cementite. It's always austenite, martinsite, avoid the pearlite. Next we'll be throwing bainite around.

I do hope this thread keeps going though. It's all starting to make a little sense. It sure would be nice to see emperical testing of each quench up to 3. But then what would you look for? If 3 quenches are best, are 2 quenches better than 1 and has anyone tested that? I'm thinking I could still go either way on this.

I was kinda OK so far until this: alpha iron (BCC) came up.
 
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