The requirement to convert from one hardness test scale to another is common practice and is covered by various International Standards (ASTM E140, ISO 18265). These standards state that, due to the differences in various types of hardness test methods, it is not possible to show a constant relationship across all materials. As such, the standards provide approximate conversions tables according to material type and it is essential to use the correct one.
Standard Hardness Conversion Tables for Metals Relationship Among Brinell Hardness, Vickers Hardness, Rockwell Hardness, Superficial Hardness, Knoop Hardness, Sceleroscope Hardnnes and Leeb Hardness.
Equations that were generated from the specific hardness numbers can be found ASTM Standard E140-12b www.asminternationa.gv
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