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Thread: Sori changes during tempering:

  1. #1
    Join Date
    Jun 2003
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    argentina
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    Sori changes during tempering:

    Hello everyone. I do differential quenching in the traditional way, in w1 steel. in water at 760 º c.I Below tempered at 180 ° c. paying Attention to Changes in the curvature of the sword in the quenching. I started to take steps Before and after.
    I Was Greatly surprised to find Significant Changes after annealing. In Some Cases Are Not as regular as the formation of sori. That a sword tip so I am a flamenco style!
    question: are common These changes?.
    There Any Way To Foresee Them or Regularly?
    here I leave a diagram with Measurements of variation of sori, from 22 to 14 mm. Movement and a tip of 25 mm approx. a picture of the sword Before tempering. and a picture of the future hamon. thank you very much, sorry for my bad Inglés, greetings, peter






  2. #2
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    Peter, language barriers are a natural part of communication on the internet, but I will try to work around some of the problems if I can. I am not certain which heat treating operation we are discussing here. In English the operation of softening the steel for hand shaping would be called "annealing". Quenching in liquid to harden the steel would be called "hardening" or "quenching". Heating the blade after the hardening in order to relieve stress and make the steel less brittle would be "tempering". I don't list all of these terms to try to be English teacher, I am not so good at it myself, but to allow you to see if I am talking about the same things you are.

    Sori is typically produced in quenching or hardening, with very fast quenching mediums like water the sori is normally increased positively (that is the blade tip rises), but in slower quenches, like oils, there can often be a loss of curvature or a negative sori (the blade tip goes down). If you got reverse or negative sori in water then you may be able to adjust your clay thickness and application to correct the problem in the future. Since water should be fast enough to cause the tip to rise the only factor that would counter that would be clay thickness interfering with the cooling.

    You must also be careful not to allow too much sori if you are starting out with the blade pre-curved before the quench. If changing your clay thickness added positive sori you could curve too much or destroy the blade. Often in water quenching the blade is almost straight and the sori from the quench gives it almost all the curvature.

  3. #3
    Join Date
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    NY State
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    I remember the comment about a maker who tried quenching in oil -- the sword curved in the opposite direction !! Many different forces during quenching so it's far too difficult to predict !
    Ascertained with certainty

  4. #4
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    Hi Kevin. thank you very much for your insights, always so correct. rereading my post, I realize the mistake I made. the change in the sori, first note after quenching, and modified again after tempering. The first picture is obtained post quenching sori . The second picture is the change in the sori after tempering. (In the first post had put anealing).
    usually slightly curved blade, that the amount of clay used in the hardening process is very fine, and gives very little sori.
    Thanks Robert, are so many factors that affect the sori that every time you think you and is controlling, something new to adjust the learning!, Greetings, peter

  5. #5
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    I understand now. Now that I understand I would like to thank you for sharing this with us. It is not often we get to see and discuss the effects of tempering on sori this clearly and your pictures give us a lot to think about metallurgically in regards to yaki ire and sori; there is an awful lot of relaxation of the lattice going on in tempering sucha sword.

  6. #6
    OK - to make certain I understand:
    The sword tip dropped 25 mm after TEMPERING.

    Wow - this is something new to me, and I appreciate you sharing. It makes sense that it could happen, now that I see it. But, I never have thought to measure or control for this.

    thank you for the pictures, they tell the story well.

    kc

  7. #7
    double post, please delete.

  8. #8
    Join Date
    Mar 2002
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    Sturgeon Bay, Wisconsin
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    Peter,
    This is not something I have noticed in my clay coated,water quenched blades.
    Interesting.

    Ric
    Richard Furrer
    Sturgeon Bay, Wisconsin
    http://doorcountyforgeworks.com/

  9. #9
    I think that is an issue of relieving the residual stresses. There are significant residual stresses present - some due to microstructure - others are due to differential cooling. I would expect that the sori would relax under tempering.
    D. Scott MacKenzie, PhD
    Metallurgist specializing in Heat Treatment and Quenching

  10. #10
    I would like to say a few things if no one minds, as I have some insight into sword forging. I could not help but to notice that you may have a hardened mune, which would prevent your blade from taking on the amount of sori you wanted and could possibly also reverse a little during the tempering cycle. Basically the steel has no idea which way it wants to go.

    Did you have any pictures of the blade pre heat treat? so I can see what I think that might answer a few questions.

  11. #11
    Join Date
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    Location
    argentina
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    hi john. Unfortunately, I have no previous photo. but I can tell you two things: usually normalized three times before the heat treatment. gradually approaching the desired temperature. I always leave a small curvature after, because using the least possible thickness in the layer of clay that produces hamon, so, yakiba line is much wider. sometimes I was uchi sori.
    at first, wearing a very thick layer of clay, and the sword took a lot of sori, and even more frequently had hagire and yakiba line was very thin.
    I have a little video of my yaki ire if you want to see. a hug peter
    sorry for my bad English!

  12. #12
    Peter beautiful hardening furnace

    You can specify the construction schedule

  13. #13
    Join Date
    Jul 2006
    Location
    london england
    Posts
    36
    I have found the curvature change that goes on in heat treating wedge shaped blades to be most interesting.
    It is a big factor when trying to plan a final blade profile.
    things I have noticed on wedge shaped single edged long blades.
    normalising often leads to reverse sori sometimes quite significant this tends to reduce with multiple normalisations.
    hardening into oil also gives reverse sori but this depends largley on the width and scrossection of the blade in other words on how great the difference is between edge and spine and how wide the blade is . Greater spine to edge difference = greater sori . Wider blade=less sori .
    this can be a real PITA on strait blades .
    I have taken to hammering dagger blades strait whilst they are meta stable austenite ...... this works well but can be nerve wracking.
    reverse sori can relax a little on tempering .

    we all know about the effects of water on a clayed blade....
    post water tempering can relax a lot of the sori (sometimes).
    I have actually seen a blade move significantly when cooling down from temper ....quite freaky .
    there is a lot going on and I don't profess to understanding all the working of it .You can however prtedict it to an extent but crosssection of an individual blade to another has a great effect .

  14. #14
    Owen I do not do the same tempering that regular knife makers do. Once I have quenched the blade and it is cool, I put it back in the forge for a count of 20 seconds then I requench the blade, according to the Japanese this relieves the stress in the blade to which I have had no problems with losing sori, and none of my blades of broken when tested.

  15. #15
    I learned that lowering
    minimum of one hour in the oven 200 degrees Celsius
    but I have also seen 20 seconds of John
    Pavel Bolf
    http://www.youtube.com/user/balzerz#p/u/0/BLXLTyn55nM
    is there a difference? what?

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