Case Depth Terms

When applying a heat treatment, such as ion nitriding, to a part, it is important to know the following case depth terms:

Effective Case Depth (ECD):

The distance from the surface of a hardened case where a specified level of hardness is maintained (typically 50 HRC eqv.).

Total Case Depth (TCD):

The distance from the surface of a hardened case to a point where differences in physical properties of the case and core are no longer distinguished (visual or hardness method).

For example:

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