The Difference And Conversion Of Rockwell Hardness, Brinell Hardness And Other Hardness

Hardness is a measure of the softness of the material. There are many different hardness test methods whose principle are definitely different, measured hardness values and meaning are not exactly the same. Brinell hardness(HB), Portable Rockwell hardness Tester (HRA, HRB, HRC), Vickers hardness (HV), rubber and plastic Shore hardness (HA, HD), etc. are the most common static load press hardness tests of which the value of the material  show its surface ability to resistant the press of hard objects. Therefore, the hardness is not a simple physical quantity, it reflects a comprehensive performance including elasticity, plasticity, strength and toughness of the material.

Hardness of steel: the code of steel Hardness is H. Depending on the different hardness test method,

• The common methods are Brinell hardness (HB), Rockwell hardness (HRC), Vickers hardness (HV), and Richard hardness (HL), among which HB and HRC are more commonly used.

• HB has wide range of applications, while HRC is suit for high hardness materials, such as heat treatment hardness. The difference between the two is that they have different probe. The probe of Brinell hardness is the carbide ball, and the probe of Rockwell hardness is diamond.
• HV is suitable for microscopic analysis. Vickers hardness (HV) press into the material surface with diamond square cone for about 120kg load and the top angle of 136 °, then the surface area of the indentation of the material is divided by the load value that is, Vickers hardness (HV ).

• HL hand-held hardness tester is easy to measure. The impact ball assaults the hardness surface to generate bounce; the hardness is calculate by the ratio of the impact speed and rebound speed at 1mm between the impact ball and the sample. The formula: Hardness HL = 1000 × VB (rebound speed) / VA (impact speed).

HB - Brinell Hardness:

Brinell hardness (HB) is generally used for the soft material, such as non-ferrous metals, steel before heat treated or after annealing. Rockwell hardness (HRC) is generally used for high hardness materials, such as the hardness after heat treatment and so on.

Brinell hardness (HB) press a certain diameter of hardened steel ball or carbide ball into the metal surface to be measured with a certain size of the test force to maintain the specified time, and then remove the test force, measuring the measured surface indentation diameter. The Brinell hardness value is the quotient of the indentation spherical surface area divided by the test force. Generally: press a certain size (diameter is generally 10mm) of hardened steel ball into the material surface with a certain test force (usually 3000kg) to maintain a period of time, then remove the test force, the ratio of load and its indentation area is the Brinell hardness (HB) in kg / mm2 (N / mm2). (For details of Brinell hardness (HB), please click "Brinell hardness tester PHB-3000")