Hardness - Coupling Information

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Hardness

Hardness of metal is the property that enables it to resist deformation. Depending on the application, the hardness may be an important consideration - especially in high load applications. Hardness testing is based on experiments and observation.

There are several methods of testing hardness including Brinell, Rockwell and Vickers which all use an indentation test. There are other hardness testing methods not discussed in this document.

Rockwell Hardness

The Rockwell C hardness test is performed by pressing a cone-shaped test piece into the boundary layer of material with a defined pressure. The remaining impression depth is measured.

For the Rockwell B procedure a steel ball is used instead of a cone.

Vickers Hardness (HV)

The Vickers test presses the point of a pyramid of diamond into the surface of the working piece for 10-30 seconds with a defined pressure. The diagonal of the resulting imprint of the pyramid is measured.

Brinell Hardness (HBW)

The Brinell hardness test is performed by pressing a tungsten carbide ball into the material surface for more than 10 seconds with a defined pressure. The Brinell hardness is determined from the diameter of the impression.

There is no exact formula for converting the results of one type of hardness test to another, however the table below gives a nearest approximation based on test results.

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More information on hardness