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Thread: Heat Treating

  1. #11

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    Quote Originally Posted by rockbox View Post
    I don't think anyone got upset. I just think Adam is making sure the knife makers here don't feel any pressure to give any info they don't want to give up. Kind of like when everyone was pressuring Dave on who manufactured his 10K stone on KF.
    Yeah, this.

  2. #12

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    Quote Originally Posted by Larrin View Post
    No one's upset that I know.
    Nor I! The above post was not a response to someone getting upset. Somebody made some comments about my thread and I wanted to make extra clear my intent.

  3. #13
    Senior Member rockbox's Avatar
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    Larrin,

    Does AEB-L benefit from triple quenching?
    "Insanity: doing the same thing over and over again and expecting different results." --Albert Einstein

  4. #14
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    Quote Originally Posted by rockbox View Post
    Larrin,

    Does AEB-L benefit from triple quenching?
    In triple quenching fast thermal cycles are used to refine the grain size. This works because you are forming a new phase: austenite. After quenching rapidly martensite is formed from austenite. Then once the steel is heated to austenite again, then new, small austenite grains form at the grain boundaries. So the new grains are small and the old grains continue to grow. While old grains reach a point where they are replaced by smaller grains, there is a functional limit, usually 3-5 cycles, but this depends on your heating and cooling rate and hold time, etc. The problem with air hardening steels like martensitic stainless steels is that a conventional triple quench creates disproportionate grain growth which creates a duplex grain structure with very small grains and very large grains. Appropriate temperatures have to be used which are dependent on steel type.

  5. #15

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    Is cryogenic HT being done at higher temperatures these days? -95F is not very cold. I remember cryo being done in liquid nitrogen to convert retained austenite. Is the Mf temp of this AEB-L that high?

    -AJ

  6. #16
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    Quote Originally Posted by ajhuff View Post
    Is cryogenic HT being done at higher temperatures these days? -95F is not very cold. I remember cryo being done in liquid nitrogen to convert retained austenite. Is the Mf temp of this AEB-L that high?

    -AJ
    Probably considerably higher. Colder temperatures give some leniency as far as time between quench and cryo, however.

  7. #17
    Senior Member peterm's Avatar
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    Wow Larrin! Are you going into your Ph.D. program to teach it? You seem to know answers to every question already!

  8. #18
    Senior Member rockbox's Avatar
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    I think AJ is also a metallurgist, so we two in our mists now.
    "Insanity: doing the same thing over and over again and expecting different results." --Albert Einstein

  9. #19
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    Adam, here is more information on AEB-L/13C26:

    https://rapidshare.com/files/2731329401/AEB-L.pdf

    http://www.smt.sandvik.com/sandvik/0...1?OpenDocument

    I've never used rapidshare so let me know if that upload worked.

  10. #20

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    Thanks Larrin.

    Not sure about the RapidShare thing Larrin, I cannot find a download link. Don't know, could be missing something.

    The 13C26 link worked though.

    So that I understand, I assume what we're talking about here is the "Batch Hardening" tables, yes?

    If I'm reading that description correctly, it says to:

    Equalize your oven to 1,560 degrees for 30 minutes

    Put the knife(s) into the oven, ramp up to 1,975 degrees and hold there for 30 more minutes

    Then take the blanks out and immediately quench them down to room temperature then immediately cryo them to -95 degrees

    Then temper at 345 degrees to get to 62 HRC

    This sounds very similar to the recipe above with the exception of the 30 minutes at high temp versus a mere 5 minutes at high temp in the AKS recipe. The 30 minutes noted here is even longer than the time stated at the lower temp from the AKS recipe.

    Anyone care to share what the difference might be?

    The blade (AEB-L in this case) would need to be wrapped in foil (Heavy Duty or the Easy Release stuff? ) for reasons I'm not confident on but I believe has to do with oxidation.

    Plate quenching....does it need to be done with those plates you can buy? Or are there alternative methods?

    How does one know it's safe to put into the cryo? Cool enough to handle bare handed? Does it need to be cooled first in the fridge?

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