Bent the tip of a CPM 3V 2mm blade

Discussion in 'General Knife Discussion' started by snowwolf, Aug 25, 2019.

  1. snowwolf

    snowwolf Gold Member Gold Member

    Nov 11, 2013
    EDIT short story: Depending on the heat treatment, yes 3V can be bent to a point it will not return to its original shape. Thanks guys for the answers :D

    Hi guys,

    I gave a little custom EDC in CPM3V to a friend. The blade is 2mm thick and obviously thinner at the tip. I knew he was going to abuse it but he surprised me with a bent tip. I thought CPM3V when bent would either go back straight or break if you go to far. Even more surprising. We fold back the tip straight and it still didn't break. I'm sure this poor tip is now quite weak.

    But I'm not sure if it's CPM3V anymore. Or if it is, was it heat treat properly.
    Some knife makers differential heat heats the blades to keep the tip softer (to prevent breaking) but I don't know if it's even possible with CPM3V.

    The short question for you: Is it possible to get a tip bent on a CPM3V blade?

    Thanks.
     
    Last edited: Aug 25, 2019
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  2. ScooterG

    ScooterG You mean Ireland? Yeah, it’s mine. Gold Member

    Mar 15, 2016
    Any pics?
     
  3. snowwolf

    snowwolf Gold Member Gold Member

    Nov 11, 2013
    Possibly, but the tip now looks fine. What are you looking for?

    The question is straight forward, can CPM3V be bent to a point it will not return in position without breaking?
     
  4. ScooterG

    ScooterG You mean Ireland? Yeah, it’s mine. Gold Member

    Mar 15, 2016
    Looks like it...
    Video
     
  5. snowwolf

    snowwolf Gold Member Gold Member

    Nov 11, 2013
    I got a reply from a nice fellow knife maker here who works with 3V...

    "A 3V tip can be bent. It shows that it has good toughness that it didn't break. A bent tip won't necessarily come back straight, though. It will be weaker as a result of this whether it is bent back or not. You can't differentially heat treat 3V because it is air hardening and not oil hardening. When you differentially harden a blade, the spine is not as hard but all of the cutting edge will be hard (so the tip will be hard even in this scenario.) Hope that helps."

    It all makes sens now :)
     
  6. snowwolf

    snowwolf Gold Member Gold Member

    Nov 11, 2013
    Thanks for the finding :D

    Oh man that's a long ass boring video. But to your point, 3V can stay bent depending how it is heat treated.
     
  7. Agith

    Agith Gold Member Gold Member

    344
    Nov 29, 2010
    Air hardening? I've never heard of that! Would love to hear more
     
  8. ShannonSteelLabs

    ShannonSteelLabs KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Sep 9, 2015
    Most tool steels and stainless steels are air hardening.

    They require still air or aluminum plates to quench and harden. Oil isnt needed.
     
  9. DocJD

    DocJD

    Jan 29, 2016
    :) I'm probably missing something here , but steel formula alone is practically meaningless without considering the HT .

    So unless you "name names" .... it doesn't mean anything . :confused:
     
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  10. Alberta Ed

    Alberta Ed

    Jun 29, 1999
    Don't give good knives to knife abusers.
     
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  11. snowwolf

    snowwolf Gold Member Gold Member

    Nov 11, 2013
    I just didn't know CPM3V could be bent enough to stay bent with average HT. I think the statement "Depending on the heat treatment, yes 3V can be bent to a point it will not return to its original shape." is accurate enough for this discussion.

    Now if someone shows me a bent blade supposedly 3V at 64RC... I will doubt both the 3V and the 64RC.
    But if the knife maker aimes more for toughness than high RC, his 3V work could bend and stay bent.
     
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  12. snowwolf

    snowwolf Gold Member Gold Member

    Nov 11, 2013
    Indeed. But the dude was very pleased and he always got it on him. He also told me that if the tip had broke, he would still carry it everyday to remind him how dumb of him it was to pry with it. So all in all this knife was made to be used. I'm still glad I gave it to him.
     
  13. Twindog

    Twindog Gold Member Gold Member

    Apr 6, 2004
    CPM 3V is known for its toughness, which means resistance to chipping, breaking and cracking. But toughness means nothing without strength, which is resistance to denting, rolling and bending. Hardness is usually a good proxy for strength.

    If you can easily bend your blade past its yield strength (bends and holds a bent shape when pressure is removed), it is very tough; but it lacks the strength to make a good knife blade. Play Dough is really tough, but makes a poor knife blade.

    What you want is a balance between toughness and strength. For your use, your knife was skewed too much toward toughness. If it were skewed too much toward strength, it would have broken.

    The tip will now bend more easily the next time and maybe break because the metal has been weakened.
     
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  14. Shotgun

    Shotgun

    Feb 3, 2006
    I bent the tip on a koster bushcraft in 3v once. I just bent it back on a piece of glass. The fact that it didn’t chip off is the point.

    Pun intended. ;)
     
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