Hardness indicates a material's ability to resist hard objects pressing into its surface. It is one of the important performance indicators of metal materials. Generally, the higher the hardness, the better the wear resistance. Commonly used hardness indicators include Brinell hardness, Rockwell hardness, and Vickers hardness.

Hardness indicates a material's ability to resist hard objects pressing into its surface. It is one of the important performance indicators of metal materials. Generally, the higher the hardness, the better the wear resistance. Commonly used hardness indicators include Brinell hardness, Rockwell hardness, and Vickers hardness.

1. Brinell hardness (HB)

Press a hardened steel ball of a certain size (usually 10mm in diameter) into the material's surface with a certain load (usually 3000kg) and keep it for a while. After the load is removed, the ratio of the load to its indentation area is the Brinell hardness value ( HB).

2. Rockwell hardness (HR)

When HB>450 or the sample is too small, the Brinell hardness test cannot be used and the Rockwell hardness measurement is used instead. It uses a diamond cone with a vertex angle of 120° or a steel ball with a diameter of 1.59 or 3.18mm to press into the surface of the material to be tested under a certain load, and the hardness of the material is calculated from the depth of the indentation.

According to the different hardness of the test material, it is expressed in three different scales:

HRA: The hardness is obtained using a 60kg load and a diamond cone intruder.

HRB: It is the hardness obtained using a 100kg load and a hardened steel ball with a diameter of 1.58mm. It is used for materials with lower hardness (such as annealed steel, cast iron, etc.).

HRC: The hardness is obtained using a 150kg load and a diamond cone intruder, and is used for materials with very high hardness (such as quenched steel, etc.).

3. Vickers hardness (HV)

Use a diamond square cone intruder with a load within 120kg and a vertex angle of 136° to press into the material surface. Divide the surface area of the indentation pits in the material by the load value, which is the Vickers hardness value (HV).

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