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Great Read On Heat Treating And Metallurgy

Discussion in 'Heat Treating' started by dancom, May 17, 2018.

  1. dancom

    dancom Dust Maker Best Shop Tool

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  2. Griff

    Griff Active Member

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    So, I decided to watch his comprehensive videos on YouTube that compliment his page, and I came away with this thought, 'I haven't even begun to heat treat my knives and I am already doing it wrong!' :confused:

    It's a real eye opener. I am going to be even more selective when it comes to steel when I am able to start knife making again after the house move in June. I had considered D2 until Mr. Fisher enlightened me to the fact to get the uttermost best out of D2 it needs cryogenic temperatures beyond dry ice, -150, where dry ice he says depending on how it was stored and packaged can be anywhere from -80 to -120, and in his mind -120 doesn't cut it!

    Anyway I am going to keep watching....
     
  3. Mythtaken

    Mythtaken Staff Member CKM Staff

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    I love Fisher's stuff. That said, it's easy to get blinded by science. Especially when you are starting out and have a limited toolset, a tiny corner of a garage or shed to work in, KISS is still your best guide. Keep to simple carbon steels, heat to non-magnetic, and you've got a useful, dependable blade. Once you get better at making knives and are ready to take things to the next level, then you can start to put some of this knowledge to work.
     
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  4. dancom

    dancom Dust Maker Best Shop Tool

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    I got started down the rabbit hole when I read some posts over on BladeForums where a poster was saying that Nitro-V won't harden without a cryo treatment. There is so much rubbish out there it's good to have a little science background so one can sniff the whooey before they step in it. Last night I heat treated and tempered two chefs knives in Nitro-V, sans cryo. They seem plenty hard to me.
     
  5. Griff

    Griff Active Member

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    The whole series of videos is passive aggressive commentary on how Jay Fisher perceives the knife making community. He's very clear about his distaste for simple carbon steels, how they are processed in an average knife shop, and then at the same time casts doubt on any other knife maker who isn't set up like he is to Heat-treat/ Cryo-treat hypereutectoid steels.

    There's so many levels to what is going on with Jay Fishers page and videos. It is the very best intentions of a master knife maker to both heat and freeze his knives to a level that scientifically proves they will be the best knives on the planet wrapped around a certain amount of disdain for other knifemakers (though probably not those he considers peers, just regular schmucks)! There's no other way to say it, its how he was coming off. At one point he clearly states he doesn't share any of this knowledge for the benefit of other knifemakers, he's doing it to educate the customer by basically saying, 'If they don't do it like I do it, then their knives are garbage,' and so its here were you can feel his contempt.

    For a fairly new knife maker such as myself this whole Jay Fisher thing was daunting, because I want to make knives made from all steels, and to the level that Jay Fisher prides himself on (I think we all do). If my skin were a bit thinner though I would have hung up my grinder by video #4 lol!
     
  6. Mythtaken

    Mythtaken Staff Member CKM Staff

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    I think you're right in much of what you're saying, @Griff. While much of Fisher's arrogance comes well-earned, he is definitely promoting his brand. Nevertheless, he does provide a wealth of information that any maker can learn from, when they decide to move down that path with more exotic steels.
     
  7. Griff

    Griff Active Member

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    @Mythtaken That part in his video where he says he doesn't share information for other makers is sad. The reason I got into this in the first place was because how open other knife makers are at sharing their knowledge, and are usually quite humble doing so...the fact that the majority of the community work and share information to make us all better knife makers - which makes the quality in the craft better overall- is far more creatively productive.
     
  8. ToddR

    ToddR Putterer, Tinkerer, Waster of Time Staff Member

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    She blinded me with science
    And failed me in geometry....

    .... great tune...
     
  9. Mythtaken

    Mythtaken Staff Member CKM Staff

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    I wondered who'd get that first....
     
  10. Grayzer86

    Grayzer86 Active Member

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    I think a bunch of this confusions comes from misinformation or improper testing. From my own experience. Cryo gets it harder, no question, and by 2-3 points. It still stabilizes and hardens with the temper, it just ends up a bit softer with more RA. I think part of the myth is caused by guys testing too soon after the plate quench. This steel, and especially AEB-L, if checked right out of the plates while still warm, is about as hard as jello. After coming down to room temp or even cold water, there is a fairly significant increase in rigidity and hardness, that is further stabilized by tempering. If guys are taking a quenched blade that is still warm and doing a hardness test, it no doubt seems very soft, because it’s still converting. Much the same as if you pulled an oil quenched blade out of the oil at say 600 degrees and file checked, it’s not done converting so it’s not going to be fully hard yet either.

    I have tried AEB-L which is a very similar steel with basically the same heat treat with and without a subzero, and I do notice a difference. Most users probably would not. Both were kitchen knives done the very same aside from the subzero. While the non sub knife is totally functional, it’s edge holding is somewhat lower than the cryo version. I attribute this mostly to the fact that I was able to squeeze another 2 points of hardness out after tempering on the knife that underwent the freeze. I now dry ice bath all of my stainless, but with that said, I have never had any type of negative feedback on any knives I was making before the dry ice either. One of my personal fillets in Aebl without cryo, and I have no complaints at all. Lower aus temp of around 1925 instead of 1965 helps with RA and final hardness with these two steels if a guy doesn’t want to do the cryo cycles as well.
     
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  11. Griff

    Griff Active Member

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    @Grayzer86 I think through your own testing then you have proven an increase in performance with a blade that was cryo-treated at just somewhere between -80 and -120F (the max dry ice gets too).

    It's stands to reason then that a blade taken to deep cryogenic levels and sustained below -300F for a greater length of time will improve upon the result you've already achieved.

    This is all very exciting stuff!
     
  12. Grayzer86

    Grayzer86 Active Member

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    @Griff i believe I have shown some performance increase yes. There should be a further reduction in RA, though a smaller percentage, when true liquid nitrogen cryo is done. The other benefit of a true cryo for extended times is the formation of ETA carbides which do not form at dry ice level temps, but can further aid in edge retention and toughness. I find that with Aebl, it’s tough enough, has enough stability, and easy enough to sharpen, that the extra hardness dry ice allows is a benefit. In a steel like this that doesn’t form any large carbides, the extra hardness allows for better edge holding. There is nothing wrong with AEB-L at 60 in and of itself, but it does leave some performance on the table when compared to AEB-L at 62-63.
     
  13. ToddR

    ToddR Putterer, Tinkerer, Waster of Time Staff Member

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    There are times when i feel so much like a newb on this forum. This is definitely one of those times. I use 01 because I can use the ol' magnet and canola oil technique. You guys do plate quenching and dry ice? I read about some guy the other day using carbonite (or maybe that was Star Wars... i dunno). Anyway, it amazes me how quickly one can get into this hobby and make something cool. But it's equally amazing how far you can go with it and still not know things. You can spend your lifetime learning more knifemaking techniques and processes. To me, that's just awesome.
     
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  14. John Noon

    John Noon Well-Known Member

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    For liquid nitrogen quench depending on the material used the time varies from zero (get it cold) all the way up to 24 hours it is not a fixed number and once the point is reached there is no benefit from doubling the time.

    For AEB-L and soon Nitro-V I plate quench and use compressed air for roughly a minute then check the blade and it should be warm to the touch.
    From there into a smaller plate clamp and into the freezer, this helps get the material down below room temperature that one of the manufacturers recommends for their version of the material.

    Before room temperature or lower is reached you can easily bend the AEB-L intentional or otherwise. Learned this the hard way when burying a blade in snow, out came a banana.

    Side note: Jay fisher used to participate in the forums many years back but he got tired of the arguments and people claiming engine oil was superior to any method he used even with testing to support his statements.
    I actually myself dropped several knife and smithing related pages on Facebook after motor oil came up for the tenth time that week. The same die-hard users proclaimed it was the best ever and pushed its use no matter what evidence to the contrary was presented. The old this is the way I do it and nothing is better mentality.

    If you start searching for Cryo Quenching you can find lots of research, some is very old before it was well understood and others are blatant attempts at someone selling their process or secret technique. Best stuff to try and locate is from the Government labs or NASA since these are for research and basically unbiased.

    One thing I am hoping to work on is an automated quenching system, basically dial a quench for knife makers.
     

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