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Brinell Hardness
10 mm diamond ball, 500 kgf load
Symbol:  HB (500) 

The Brinell Hardness Test, commonly used for metallic materials, determines hardness by applying a known load (3000, 1500, or 500 kgf) to the surface of the test specimen via a hardened steel or diamond ball of prescribed size (10 mm in diameter).

The size of the permanent impression on the specimen surface is converted into a Brinell Hardness Number (HB) according to the formula:

A measurement is considered valid if the diameter of the permanent impression is in the range of 2.5 to 4.75 mm (slightly exceeding this limit is tolerated). As a result, the 3000 kgf load yields HB measures between 160 and 600; the 1500 kgf load, HB 80 to 300; and the 500 kgf load, HB 26 to 100. Smaller loads (e.g., 250, 125, 100 kgf) can be used for softer metals.

According to the ASTM (American Society for Testing and Materials) Standard E10-66, a steel ball may be used up to HB 450, and carbide may be used up to HB 630. It is NOT recommended to use the Brinell test on materials harder than HB 630. These limits were set to avoid errors introduced by the deformation of the ball indenter itself.

Convert   HB (500)       
(suggested range: 89 ~ 189)
  HB (500)   139   approximately*
Symbol Amount Name Suggested
HB (3000)  153   Brinell 10 mm Standard 3000 kgf  80~445
HB (Tungsten 3000)  153   Brinell 10 mm Tungsten 3000 kgf  80~620
HB (Indentation)  4.85 mm   Brinell Indentation  6~2
HK  173   Knoop  97~920
HM  2.5   Mohs  1~10
HRA  << Rockwell A-Scale  59~86
HRB  82   Rockwell B-Scale  41~100
HRC  << Rockwell C-Scale  19~69
HRD  << Rockwell D-Scale  39~77
HRF  >> Rockwell F-Scale  88~100
HR-15N  << Rockwell Superficial 15N  69~94
HR-15T  88   Rockwell Superficial 15T  77~93
HR-30N  << Rockwell Superficial 30N  41~85
HR-30T  72   Rockwell Superficial 30T  53~82
HR-45N  << Rockwell Superficial 45N  19~76
HR-45T  56   Rockwell Superficial 45T  28~71
HS  24   Shore Scleroscope  17~97
Approx. TS  521 MPa   Tensile Strength (Approx.)  390~2450
HV  161   Vickers  20~1800

<< The hardness value is below the acceptable range of the particular hardness scale.
>> The hardness value is above the acceptable range of the particular hardness scale.
### The hardness value is near the limit (within 15%) of the acceptable range of the particular hardness scale.
* The many hardness tests listed here measure hardness under different experimental conditions (e.g. indenters made in different sizes, shapes, and materials, and applied with different loads) and reduce their data using different formulae. As a result, there is NO direct analytic conversion between hardness measures. Instead, one must correlate test results across the multiple hardness tests.

This calculator is based on hardness data compiled from ASM Metals Reference Book 3rd ed, published by ASM International, and Machinery's Handbook 25th ed, published by Industrial Press. The calculator curve-fits multiple hardness data onto a common polynomial basis and then performs an analytic conversion. The accuracy of the conversion depends on the accuracy of the provided data and the resulting curve-fits, and on the valid ranges spanned by the different hardness tests. Converted hardness values should be used for comparative purposes only.