Difference Of HRA, HRB And HRC In Rockwell Hardness

DALIAN, China - April 16, 2023 - PRLog -- A, B and C in HRA, HRB and HRC in Rockwell hardness are three different standards, called scale A, scale B and scale C. Rockwell hardness test is one of several common indentation hardness tests used today. The initial pressure of the three scales is 98 07N (10 kgf), and finally calculate the hardness value according to the indentation depth. Scale A uses a sphere-conical diamond indenter and then pressurizes to 588 4N (60kgf); Scale B uses a steel ball with a diameter of 1. 588 mm (1/16 inch) as the indenter, and then pressurizes it to 980 7N (100kgf); Scale C uses the same spherical cone diamond as scale A as the indenter, but the force after pressurization is 1471N (150kgf).

Therefore, scale B is suitable for relatively soft materials, while scale C is suitable for harder materials. Practice has proved that there is an approximate corresponding relationship between various hardness values of metal materials and between hardness values and strength values. Because the hardness value is determined by the initial plastic deformation resistance and the continuous plastic deformation resistance, the higher the strength of the material, the higher the plastic deformation resistance, and the higher the hardness value. However, the conversion relationship of various materials is not the same – hardness conversion formula:

Hardness Conversion Formula

1. Shore hardness (HS)=Brinell hardness (BHN)/10+12
2. Shore hardness (HS)=Rockwell hardness (HRC)+15
3. Brinell hardness (BIHN)=Rockwell hardness (HV)
4. Rockwell hardness (HRC)=Brinell hardness (BHN)/10-3 hardness measurement range:

HS<100HB<500HRC<70HV<1300 (80~88) HRA, (85~95) HRB, (20~70) HRC Rockwell hardness in HRA, HRB, HRC, etc. A, B, C are three different standards, called scale A, scale B, and scale C. Rockwell hardness test is one of several common indentation hardness tests used today. The initial pressure of the three scales is 98.07N (10 kgf). Finally, the hardness value is calculated according to the indentation depth. Scale A uses a sphere-conical diamond indenter and then pressurizes to 588 4N (60kgf); Scale B uses a steel ball with a diameter of 1. 588 mm (1/16 inch) as the indenter, and then pressurizes it to 980 7N (100kgf); Scale C uses the same spherical cone diamond as scale A as the indenter, but the force after pressurization is 1471N (150kgf).
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