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Thread: Just wondering whats the hardest knife?

  1. #1
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    Just wondering whats the hardest knife?


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    from searchin the wed and ebay. I just found HRC 67 the hardest for a kinfe right now. WILLIAM HENRY high end knife HRC is 67 Koji Hara using Cowry-Y powdered steel 2 made the knife HRC 67. I m just wondering is there any other knife that is harder than 67
    HRC? Is there anything in the market thats right now that the HRC is higher than 7 ?
    I m talkin about small knife like folding knife. since thats the one i done research on and needed.
    Last edited by 70939488; 06-11-2008 at 08:18 PM.

  2. #2
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    Your decimal point is off.
    Should read 67 HRC

    And no, I do not know of any knives with harder blades.

  3. #3
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    Ceramic blades like from Kiocera or Boker should be alot harder.

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    Does a scalpel count as a knife? There are ones with (synthetic) diamond blades.

  5. #5
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    Thanks for the info guys. this is a good read about diamond ceramic steel
    http://www.crstoday.com/PDF%20Articl...RST0607_14.php
    Last edited by 70939488; 06-11-2008 at 09:02 PM.

  6. #6
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    Ceramic is in the 80s HRC, and a perfect diamond is in the 90s. The scale is logarithmic, too (with 100HRC being infinitely hard), so going from 80-90HRC is orders of magnitude more of an increase than going from 50-60HRC.

    Diamond blades are often used for eye surgery, microsurgery, and specimen cutting for electron microscopes.

  7. #7
    Buddy of mine made an axe with a special alloy that had an HRC of 100. Went to split a log with it, cut through the log, through the stump it was on, down through the ground and he's now falling toward the center of the earth somewhere. Pretty awful. Stick to knives in the 60s.

  8. #8
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    Quote Originally Posted by Buhbuhbonky View Post
    Buddy of mine made an axe with a special alloy that had an HRC of 100. Went to split a log with it, cut through the log, through the stump it was on, down through the ground and he's now falling toward the center of the earth somewhere. Pretty awful. Stick to knives in the 60s.
    Let me guess... the Adamantium axe? LOL

  9. #9
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    The Rockwell C scale only goes to 70 !! There's more to a blade than hardness.Hardness measures the strength of the matrix not the wear resistance of the carbides !

  10. #10
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    I have an excellent Kyocera gentlemen's knife with their new HIP ceramic blade (which actually looks somewhat Damascus-like). It is astoundingly sharp and it holds an edge very well. Since the blade is ceramic you have to watch out a bit how you will be using it. But within these constraints, it works amazingly well. Unfortunately I don't know the HRC. Does anyone have an idea about the HRC of this recent 'HIP" ceramic blade?

  11. #11
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    It's ceramic not steel so the hardness would be measured by some other system than Rockwell.

  12. #12
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    Quote Originally Posted by znode View Post
    Ceramic is in the 80s HRC, and a perfect diamond is in the 90s. The scale is logarithmic, too (with 100HRC being infinitely hard), so going from 80-90HRC is orders of magnitude more of an increase than going from 50-60HRC.

    Diamond blades are often used for eye surgery, microsurgery, and specimen cutting for electron microscopes.
    Quote Originally Posted by mete View Post
    The Rockwell C scale only goes to 70 !! There's more to a blade than hardness.Hardness measures the strength of the matrix not the wear resistance of the carbides !
    I think you are both right. The Rockwell C scale, although it actually runs to 100, is only measurable up to about 70 because it is based on a specific measurement technique. That technique is not viable much above 70.

    http://www.gordonengland.co.uk/hardness/ehe.htm

    http://www.gordonengland.co.uk/hardness/rockwell.htm

    I think the Vickers scale and the Brinnel scale are used for harder materials.

  13. #13
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    > It's ceramic not steel so the hardness would be measured by some other system than Rockwell.

    Yes, I found meanwhile that a standard called Moh is often used for ceramics. It measures scratchability. I also found that standard Kyocera blades have a hardness of around Moh 8.2, which after conversion falls outside the normal HRC range (above 69). I couldn't find a Moh number for the special damascus-like HIP blade as used in my ceramic pocket knife:


  14. #14
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    Quote Originally Posted by Dagon View Post
    > It's ceramic not steel so the hardness would be measured by some other system than Rockwell.

    Yes, I found meanwhile that a standard called Moh is often used for ceramics. It measures scratchability. I also found that standard Kyocera blades have a hardness of around Moh 8.2, which after conversion falls outside the normal HRC range (above 69). I couldn't find a Moh number for the special damascus-like HIP blade as used in my ceramic pocket knife:

    You mean the Mohs scale? A knife blade of 8.2... about as hard as topaz. If I remember correctly...

    Talc- 1 (makes sense, talcum powder= baby powder)
    Gypsum- 2
    Calcite- 3
    Fluorite- 4 (penny)
    Apatite- 5 (tooth enamel)
    Orthoclase (feldspar)- 6 (a steel blade is around 5.5)
    Quartz- 7 (files are about 6.5)
    Topaz- 8
    Corundum- 9
    Diamond- 10

    There is also an extended Mohs scale, bumping diamond to 15 and putting fused alumina, fused silica, silicon carbide and boron carbide at the middle slots, with garnet as the new 10.

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    Quote Originally Posted by 70939488 View Post
    Thanks for the info guys. this is a good read about diamond ceramic steel
    http://www.crstoday.com/PDF%20Articl...RST0607_14.php
    Your good read is not about "diamond ceramic steel". It is about using small blades made of pure diamond for eye surgery as scalpels.

    While techically interesting, this has no significant value for utility knife blades. The expense and the fragility of the blades would preclude their use, much as ceramic blades tend to break on light impact, however sharp they seem to be.

  16. #16
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    Quote Originally Posted by Esav Benyamin View Post
    Your good read is not about "diamond ceramic steel". It is about using small blades made of pure diamond for eye surgery as scalpels.

    While techically interesting, this has no significant value for utility knife blades. The expense and the fragility of the blades would preclude their use, much as ceramic blades tend to break on light impact, however sharp they seem to be.
    Esav i m now wondering can they use other steel and do it San Mai III style and sandwich creamic or tungsten with other still 2 make it more unbreakable? i m not a blacksmirth.maybe you know the answer. that link did talk about creamic and diamond steel if you did really read it. I m not a steel pro or not in 2 steel untill i bought a G SAKAI KOJI HARA RARE CUSTOM BLACK PEARL BAMBOO knife this week but yesterday at dinner my older brother took it. thinkin is a faterday gift. thats why i want a knife made in here.

  17. #17
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    Before you can begin to decide what steel you need, please read this:
    Steel FAQ By Joe Talmadge at http://www.bladeforums.com/forums/sh...d.php?t=368828

  18. #18
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    Quote Originally Posted by Dagon View Post
    > It's ceramic not steel so the hardness would be measured by some other system than Rockwell.

    Yes, I found meanwhile that a standard called Moh is often used for ceramics. It measures scratchability. I also found that standard Kyocera blades have a hardness of around Moh 8.2, which after conversion falls outside the normal HRC range (above 69). I couldn't find a Moh number for the special damascus-like HIP blade as used in my ceramic pocket knife:

    Where'd you pick that up?

  19. #19
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    > Where'd you pick that up?

    Here.
    It is a truly fantastic gentleman knife. Not cheap, but it offers quality, if you can live with the constraints of a ceramic blade (which I think are pretty ok for a gentlemen knife).

  20. #20
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    Very hard but also very brittle...

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