Rockwell Hardness Tester
HR = E - e
- F0 = preliminary minor load in kgf
- F1 = additional major load in kgf
- F = total load in kgf
- e = permanent increase in depth of penetration due to major load F1 measured in units of 0.002 mm
- E = a constant depending on form of indenter: 100 units for diamond indenter, 130 units for steel ball indenter
- HR = Rockwell hardness number
- D = diameter of steel ball