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Heat treat discoloration

Discussion in 'Shop Talk - BladeSmith Questions and Answers' started by rjedoaks, Mar 27, 2019.

  1. rjedoaks

    rjedoaks Gold Member Gold Member

    Sep 15, 2009
    B6D7A3D0-40B1-4953-A915-F32AAA98EA8A.jpeg What is causing this? It is a bit less pronounced after tempering. Uneven heating? O1
  2. DevinT

    DevinT KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Jan 29, 2010
    How did you heat treat it?

  3. rjedoaks

    rjedoaks Gold Member Gold Member

    Sep 15, 2009
    With a forge. I have done many, this is the first time this has happened.
  4. Sam Dean

    Sam Dean Gold Member Gold Member

    Aug 3, 2012
    After warm oil quench, mine (in O1) are pretty scaly, but not necessarily discolored. After 450 deg tempering, they're straw colored with just a hint of purple & test at 60/61Rc.

    Any problems I've had with O1, which aren't many (low post quench hardness), had to do with not soaking it long enough at temp. Erring on the longer side of soak time seems to resolve it.
  5. John mc c

    John mc c

    Aug 23, 2018
    I often get this from forging o1
    It's from high temps but not high enough to ruin it as can happen with o1.I think and hope
    Too high is bubble like circles on blade
    As far as I know

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