Toughness

Toughness

In machining, the term toughness usually refers to the fracture toughness of carbide grades.
Fracture toughness is one of the most important parameters for design applications and performance assessment of cemented carbides.

It is represented by the KIc and measured in MPa – m1/2 (or ksi – in1/2).

Fracture toughness: is a fundamental materials property, indicating the strain energy–absorbing ability of a material prior to fracture.
It is a crucial parameter since it indicates the resistance to cracks, breakages, and impact of the carbide grades.
The higher the fracture toughness, the higher the material resistance to crack propagation.

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.

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