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Heat Treating of Knives

Discussion in 'The Cutting Edge' started by George Tichbourne, Jun 14, 2010.

  1. George Tichbourne

    George Tichbourne Deceased

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    Just following up on the D2 Question. Thought that I aught to expand on the discussion.

    What is involved in heat treating a knife blade?

    First and foremost there must be enough carbon content in the steel to harden it....in the region of 1 to 2 %....too little carbon there will not be enough carbide crystals formed to give the edge wear resistance. Too much and we end up with a brittle blade that cannot be tempered enough to remove that brittleness. Think cast iron which can be broken with a hammer even in thick sections.

    Secondly the steel must be heated above a critical temperature unique to that particular steel to release the crystal structure already in the metal and allow the free carbon to form carbon centered crystals called carbides. The more carbides the more wear resistant the blade will be.

    Thirdly after heat treating the blade will usually be very hard and brittle so it must be tempered to remove that brittleness by heating to a medium temperature, usually 300 to 500 degrees F.

    These are basic rules only there are exceptions based on the chemistry of the particular metal used and the desired use.

    The purpose of heat treating is to create a wear resistant blade with sufficient flex to resist breakage.

    I am leaving this thread open to allow as many people who have questions to ask them. Please feel free to contribute.

    George
     
  2. George Tichbourne

    George Tichbourne Deceased

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  3. Tazz10m

    Tazz10m Mod Aerator Moderator Millennium Member

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    Thanks George! As a knife maker, i can never get enough info on heat treating. There is so much to it it's absolutely amazing. And the difference between metal that's been properly heat treated, and one that hasn't been heat treated at all, is night and day. Do you do your own heat treat or do you have someone else do it? And if someone else, who? Btw, LOVE your knives! You are one of the guys that inspired me to get into making my own. You ROCK!
     
  4. George Tichbourne

    George Tichbourne Deceased

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    You have got me blushing Brooks with all your praise.

    No, I do not do my own heat treating. With the stainless steels that I use the heat treating must be done in an inert atmosphere so I take my blades to a heat treater about 5 blocks away to be heat treated. They have state of the art heat treating ovens and run 24/7, with all that practice they are very good. There is no real reason for me to try to do it myself given the risks involved if I fail to do it right.

    Always happy to help anyone who wants to or already makes knives.

    George