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.
|HB (Indentation) 3 mm approximately* =|
|HB (3000)||413||Brinell 10 mm Standard 3000 kgf||80~445|
|HB (500)||>>||Brinell 10 mm Standard 500 kgf||89~189|
|HB (Tungsten 3000)||413||Brinell 10 mm Tungsten 3000 kgf||80~620|
|HR-15N||83||Rockwell Superficial 15N||69~94|
|HR-15T||>>||Rockwell Superficial 15T||77~93|
|HR-30N||63||Rockwell Superficial 30N||41~85|
|HR-30T||>>||Rockwell Superficial 30T||53~82|
|HR-45N||48||Rockwell Superficial 45N||19~76|
|HR-45T||>>||Rockwell Superficial 45T||28~71|
|Approx. TS||1442 MPa||Tensile Strength (Approx.)||390~2450|
|<<||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.