ZT 0350 snapped!

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  • FordMan08

    Shooter
    Rating - 96.2%
    24   1   1
    Nov 26, 2008
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    Parts Unknown
    My everyday carry knife snapped in two. I was sawing off the antlers on an old deer skull (with a saw, not the knife). I was through the skull and had a gap with a little bit of bone left in tact. I couldn’t get the saw blade in there so I grabbed my knife just to pop the bone in two. With little pressure on the blade it snapped like a twig. I just starred in disbelief for a minute. I’ve watched torture tests on these knives and I wasn’t even at 5% of what I’ve seen them go through. I wonder if they’ll replace it. Sucks either way.
     

    Expat

    Pdub
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    Feb 27, 2010
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    Well that would suck... one has to wonder how many of us carry a knife that would do exactly that when some pressure was put on it. About the toughest thing I do is cut cardboard with mine.
     

    moosehead

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    Mar 11, 2013
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    I may be wrong about this, but I imagine the powdered (sintered)steel blades are a lot more likely to break when using them to pry. They’re great for cutting, and holding an edge, but anything else is a crapshoot.
     

    bwframe

    Loneranger
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    Feb 11, 2008
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    Not knocking the OP, but I learned a lot of years ago that tools with dedicated sharp edges are meant for cutting. Other tools are designed for prying.
     

    Expat

    Pdub
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    Not knocking the OP, but I learned a lot of years ago that tools with dedicated sharp edges are meant for cutting. Other tools are designed for prying.
    Agreed and none of us knows how much pressure the OP put on the blade other than him. But I would like to think my blade wouldn't snap in two the first time it hit bone or another blade, if I ever had to use it in a self defense scenario.
     

    rhino

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    Mar 18, 2008
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    I may be wrong about this, but I imagine the powdered (sintered)steel blades are a lot more likely to break when using them to pry. They’re great for cutting, and holding an edge, but anything else is a crapshoot.

    Depends on the heat treatment more than anything else.
     

    OutdoorDad

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    Apr 19, 2015
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    Depends on the heat treatment more than anything else.

    I abandoned a degree in aerospace engineering before we got into metallurgy. And I know you have an extensive knowledge of blades, so I'll defer to your experience.

    But are you saying that heat treatment is more important to the forces involved in prying than the sintered construction of the blade? And I had no idea that they were making sintered blades to be honest.
     
    Last edited:

    rhino

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    I abandoned a degree in aerospace engineering before we got into metallurgy. And I know you have an extensive knowledge of blades, so I'll defer to your experience.

    But are you saying that heat treatment is more important to the forces involved in prying than the sintered construction of the blade? And I had no idea that they were making sintered blades to be honest.

    Absolutely. Composition also plays a big role. For example, CPM 3V has potential for enormous toughness and resistance to bending stresses when properly heat treated. That's why it's the current rage for choppers, knives that may be abused, and small knives with very thin blades.

    The main difference between bar stock of a CPM steel and a conventional steel is the uniformity of the material. The elements in the CPM alloy are uniformly distributed and the carbides that formed are as well. Because of that, the physical properties are uniform and predictable far beyond what you'd get with a conventionally manufactured steel. A CPM or similar steel is less likely to have a localized flaw that would compromise the physical properties of the finished product. CPM alloys start life superior in just about every way other than cost.

    An analogy could be made to MIM parts vs. forged and machined. MIM gets a bad rap, but invariably the MIM parts that perform poorly we only surface hardened as part of delivering the part at a specific price point.

    Also, the blade themselves are not produced via a sintering process as you would with other finished products. Blades are machined/grounds to shape from bar stock, not sintered from the powdered metal.

    In terms of that ZT0350 blade snapping, the most likely culprits are a heat treatment issues that produced a weakness, an issue with an impurity or other compositional flaw that produced a weak point, or an existing mechanical defect like a small crack that had already started (could also be related to heat treatment). Of those, impurities and composition issues including non-uniform distribution of the components elements is far less likely with a CPM alloy.
     
    Last edited:

    OutdoorDad

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    1   0   0
    Apr 19, 2015
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    Absolutely. Composition also plays a big role. For example, CPM 3V has potential for enormous toughness and resistance to bending stresses when properly heat treated. That's why it's the current rage for choppers, knives that may be abused, and small knives with very thin blades.

    The main difference between bar stock of a CPM steel and a conventional steel is the uniformity of the material. The elements in the CPM alloy are uniformly distributed and the carbides that formed are as well. Because of that, the physical properties are uniform and predictable far beyond what you'd get with a conventionally manufactured steel. A CPM or similar steel is less likely to have a localized flaw that would compromise the physical properties of the finished product. CPM alloys start life superior in just about every way other than cost.

    An analogy could be made to MIM parts vs. forged and machined. MIM gets a bad rap, but invariably the MIM parts that perform poorly we only surface hardened as part of delivering the part at a specific price point.

    Also, the blade themselves are not produced via a sintering process as you would with other finished products. Blades are machined/grounds to shape from bar stock, not sintered from the powdered metal.

    In terms of that ZT0350 blade snapping, the most likely culprits are a heat treatment issues that produced a weakness, an issue with an impurity or other compositional flaw that produced a weak point, or an existing mechanical defect like a small crack that had already started (could also be related to heat treatment). Of those, impurities and composition issues including non-uniform distribution of the components elements is far less likely with a CPM alloy.

    Thanks for the education!!
    Fascinating how complex it has all become.
     
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