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In machining, the term toughness usually refers to the fracture toughness of carbide grades. It is represented by the KIc and measured in Mpa – m1/2 (or ksi – in1/2).

It is a crucial parameter since it indicates the resistance to cracks, breakages, and impact of the carbide grades. Therefore a Tougher Grade will have better performance and longer tool-life in conditions such as:

  • Vibrations.
  • Machining with heavy impacts such as Milling or intermitted turning.
  • Machining where the material is being pushed rather than cut, such as parting-off to the center of a workpiece.

Unfortunately, better toughness always means lower hardness resulting in a grade with less wear resistance.


Finding the right balance between Harness and Toughness in a carbide grade is the #1 factor in its suitability for an application!

  • Tough grades will have a larger grain size and higher cobalt content.
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