Eye opening quench test results.

Discussion in 'Shop Talk - BladeSmith Questions and Answers' started by Kevin R. Cashen, Sep 23, 2010.

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  1. Nebulae


    Aug 24, 2009
    Tai, its not what you said, its how, and why you said it. As a matter of course when dealing with people on the internet one should treat them with the utmost respect, as you really have no idea who the other person is. Now in this case We know Kevin Cashen (at least somewhat), and not only is he spectacularly knowledgeable on everything concerning metallurgy and knife making, but he does his best to extend that knowledge to those of us groping around in the dark. In short, be more respectful, Kevin Cashen deserves your respect

    just my $.02
  2. me2


    Oct 11, 2003
    Are the dark spots on the left side micrographs also pearlite, or just inclusions/artifacts?
  3. Tai Goo

    Tai Goo Banned BANNED

    Apr 7, 2006
    Mace, I really don't know, but maybe it's only when people seem to perceive some kind of person threat... If all I did was suck up and kiss ass,… I don't think there would be a problem.

    I’m not a politician, I’m a bladesmith.

    Anyway, I think I've played a clean and fair game,... and am not the one who has dragged it down to a personal level.

    It seemed like the topic was drifting before I came on and some folks were inferring things from the original post that weren't in it,… so I just tried to summarize what the topic was about, which most people seem to agree on.

    I try not to take things personal, but when my name is used and the statement is directly towards me,… it’s hard not to.
  4. Kevin R. Cashen

    Kevin R. Cashen

    Sep 9, 2003
    A very well placed question ;). It is worth noting that rarely do we get 100% of everything we want, and the fact that it is often just getting the most we can get which makes our choice of quench mediums as relevant as it is. This is much the same with retained austenite, we would like to think it is black and white and if we just do this or that we can get 100% martensite, but there is a reason Mf on the isothermal transformation diagram is now expressed in an M % instead.

    The larger, darker spots are some fine pearlite, it is 1095 after all, but many of the really fine specks are carbides. Of even more interest are the linear streaks (not the scratches from my rough polish) that if you view at greater resolution are made up of even finer dark particles, this is the elongated inconsistencies in the steel from ingot segregations drawn out along with the bar stock, in these spots you will get contaminants or often collections of carbide caught up in the particle drag of that area.

    Pearlite alone does not make up the total differences between the two since so much carbon is needed to make that pearlite, thus with more pearlite, the less of these other carbon based artifacts you will have, and of course the martensite will be different as well since it will have a different carbon content. Assuming you had all that carbon in solution to begin with, carbon lost to pearlite at around 1000F would result in more lath type martensite, which would put Ms at a much higher temperature. Also the formation of pearlite is an exothermic reaction- it gives off heat! So if your quench allows that reaction to get a toe hold at 1000F it will have a harder fight on its hands to stop it than what a more effective quenchant would.

    I really could go on for pages about the many factors that come into play with the chemistry and phases at each temperature on the cooling curve, so it is really obvious why approaching it with an oversimplified perspective is just not realistic.

    Edited to add: It is easy to sit back and ignore a mistake made by one you respect, but it takes extra consideration and good intentions to correct an error made by a friend. So I would like to give credit and a thumbs up to Nathan for pointing out a typing error I have made more than once in discussing martensite morphologies. Lath martensite, which is pronounced just as it is spelled, is not spelled nor pronounced like the wood turning tool. somehow, without even noticing, I have gotten into the habit of randomly substituting one for the other. My typing is already so atrocious that I type most everything I post in MS Word, quickly spell check and then paste to the forums, in this process I often also get help from spell checkers in replacing words as well, but somewhere in all of these factors I have an error which I do not wish to pass onto others. Thank you Nathan for caring enough to help me be a better communicator. :thumbup:

    P.S. my wife has also pointed out that tricky little “e” sneaking into other words I spell, envelope vs envelop and blonde vs blond just to name a couple:eek:
    Last edited: Sep 26, 2010
  5. Mark Behnke

    Mark Behnke

    Apr 16, 2008
    Thanks for posting and, teaching.
  6. deloid


    Dec 19, 2007
    I enjoy this forum and all of the participants. It saddens me when I see personality clashes rise, without cause, and derail the giving nature or intent of the thread.

    I will eventually know most of you folks at a personal level as I start attending the meets so I have a vested interest in seeing harmony within this group of talented individuals.

    Kevin’s post was interesting but it wasn’t a scientific presentation nor was it meant to be. The statement was clear and the visuals had a great impact. That simple post had me backtracking on many old posts and it will change the way I approach heat treating AND it will throw me into my scientific mode of analyzing past studies for their methodology, set up, controls and conclusions. This is fascinating material.

    Tai, another talented participant, made a simple non threatening statement that essentially supported the concepts well known limitations and what happens? A group of people gang up on Tai as if he had written something offensive. Well good people, this is an example of personality clash, style clash and or bad interpersonal history. None of this belongs on this type of a thread and frankly it shouldn’t be part of any forum. On the other hand, disagreements, right or wrong should be a component to a forum if people want to see growth and provocative ideas that can help a field or individuals to flourish. These two facets that are inherently part of this genre can have similar origins but are quite different.

    So I ask politely. As a member of this big family, will you all try to restrain your hostility and if necessary let loose in a private manner?

    As to the Kevin's post...Thanks Kevin. The graphic (with bias or not) sent me on a delightful path that lead back to old posts of yours on high temp and low tem salt baths. I have ideas about creating a safer working bath via ultrasonic agitation (to prevent big nasty bubbles of explosive molten salt).
    Last edited: Sep 25, 2010
  7. Phillip Patton

    Phillip Patton KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Jul 25, 2005
    Just tell everyone it's the British spelling. ;):D
  8. OldPhysics


    Sep 2, 2006

    I hope you'll post its availability here. I believe I will pick it up -- I have a professional interest in what you have to say.:)
  9. Mike157

    Mike157 Gold Member Gold Member

    Aug 29, 2006
    Hi Kevin,
    I/we really appreciate your posting your work. Not only is it very interesting but educational. I love reading this type of well presented information. Please keep it up. Being as obsessive as I am, now I'm going to require everyone I buy a knife from to show some proof of proper heat treating (just joking, sort of). Though I don't know what the thermal process for the formation of pearlite is, I believe you mean't to say that its formation was exothermic if it gives off heat upon formation. Mike
  10. Robert Dark

    Robert Dark

    Aug 27, 2004
    Kevin........ Always the gentleman........ always to the point and on topic. My hat is off to you sir with a courtesy bow included.

    I really appreciate your sharing your findings with us little people. Maybe, just maybe, I will live long enough to understand some of what you are trying to impart.

    Thank you pal,

  11. VaughnT


    Feb 7, 2010
    Ha! I finally know something that KC doesn't!! What an auspicious day! :D

    "Blonde" and "Blond" are both quite correct and correspond to the feminine and masculine forms in french. "Blonde" is still quite popular in Europe, though it has seen it's hayday in America because it's just too long to spell.

    Glad I could help. ;)

    Now, what I don't understand is how a bunch of trained and experienced oil makers could be so far off with their mix. You'd think they would be able to get better results than the micrograph shows.
  12. Stacy E. Apelt - Bladesmith

    Stacy E. Apelt - Bladesmith ilmarinen - MODERATOR Moderator Knifemaker / Craftsman / Service Provider

    Aug 20, 2004
    Hopefully they will tweak the formula and have Kevin try again. Too many times ,in some industries, if the results aren't what you want you hire different testers.
  13. deloid


    Dec 19, 2007
    The images are an excellent example of what microscopic study can reveal that is not visible by visual examination or the unreliable file test.

    This didn't illustrate whether "the experienced oil makers failed". It might have accomplished this if the comparison was done in a scientific manner either as a primary study or following a method that has been proven, through study and repeatability. Kevin didn't mention this but again...I don't think this was the point.
    I think the impact of this thread is powerful due to the uncertainty and vulnerability we will now feel after heat treating our well made blades.
  14. Kevin R. Cashen

    Kevin R. Cashen

    Sep 9, 2003
    I did, and believe it or not I sat up in bed this morning realizing that typo as well, corrected it and then read your post. Excuse my sloppy fingers as I am now a wee bit distracted in this thread.
  15. sunshadow


    Oct 2, 2006
    As someone who spends about half of the average work day looking at metal through a microscope characterizing defects and failures (unfortunately we do not do steel where I work, everything we make goes into a turbine, jet engine or spacecraft) I really appreciate what Kevin is sharing with the original post. The most important part of making any functional metal object is the heat treatment. I would actually put that in front of chemistry in terms of importance. The two are intertwined since proper heat treat is determined by fitting the heat treat to the chemistry of the metal to optimize its properties.
    Thanks for sharing these slides. I look forward to having another good engineered oil available when they finish developing it. Hopefully it will be easier to get than Parks.

  16. Kevin R. Cashen

    Kevin R. Cashen

    Sep 9, 2003

    Deloid, I understand your perspective considering your relationship to the participants in this little exchange but you are perhaps judging good people based on an isolated incident without looking at the much larger timeline. As some have pointed out, intent can mean as much as content and past actions can give insight as to ones intent. I can assure you the derailment was with cause and quite intentional.

    The folks who are drawing your criticism have the benefit of watching this scene repeated ad nauseum over the years and are reacting as any person with a sense of decency would when they have just simply had enough and expect better behavior from the offender. Despite the appearance from a limited frame of reference they are not the aggressors here, they are good people who have reach their limits, I would like them to know they are appreciated for not enabling ongoing bad behavior by excusing or condoning it.

    It is quite simple, if your friend’s antipathy for me makes it impossible for him participate in a respectful or constructive manner he can simply ignore my posts. I cannot recommend this enough due to the serenity I get from ignoring anything that has his name attached to it. Something the good folks with a broader perspective on the matter can testify to my patience with.
  17. Kevin R. Cashen

    Kevin R. Cashen

    Sep 9, 2003
    Sorry, to dampen your spirits too much, but I was aware the gender specific European usage, I just can't keep it straight and spell correctly. But I can almost guarantee your knowledge of spelling and grammar is superior to mine;)

    In fact, in a bit of irony when I just ran the spell checker on this, both "spelling" and "grammar" were misspelled:eek:

    The quench oil makers were not that far off at all, we are talking about a few seconds here, and we knew that this was just the baseline to start from. To simply go right over the top in speed would be no advantage over just using water, so you then start safe and bump the properties you want incrementally under controlled circumstances. I just get the benefit of watching and gathering all this related information on the way.
  18. Justin King

    Justin King

    Nov 8, 2009
    Thanks for the thread Kevin. Those who look for information on forums are used to having to sort it out amongst the chaff. This thread is no different in that regard but is certainly worthy of the effort.
    Last edited: Sep 26, 2010
  19. Kevin R. Cashen

    Kevin R. Cashen

    Sep 9, 2003
    Thank you so much Robert, that was itself a very gentlemanly post. I don't say this because you seem to be taking my side in a silly schoolyard type altercation, but because you appreciate the virtues of making solid, cogent points in the pursuit of civil and objective conversations.

    I don't believe there are any little people, and if there were I would be one of them. We all should have equal potential in expanding our understanding, we can diminish ourselves only by self imposed limits on that understanding, but nobody has a right to limit others in that pursuit.
  20. Rick Marchand

    Rick Marchand Donkey on the Edge Moderator

    Jan 6, 2005
    That is just the wind blowing down from Canada, Kevin...;) Next, comes the u's.....colour, honour, etc.... Your spelling looks fine to this French-Canukian..

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