Hardness Conversion Formulas for Steel
Rockwell to Brinell (error expected to be +/- 10%)
from "Indentation Hardness Testing" by V.E. Lysaght, p.134For 40 < Rockwell B < 100For 30 < Rockwell E < 100Brinell = 7300 / (130 - Rockwell B)
For 10 < Rockwell C < 40Brinell = 3710 / (130 - Rockwell E)
For 40 < Rockwell C < 70Brinell = (1520000 - 4500 Rockwell C) / (100 - Rockwell C)2
Brinell = (25000 - 10 (57 - Rockwell C)2 ) / (100 - Rockwell C)2
Hardness to Tensile Strength (error expected to be +/- 15%)
from "Indentation Hardness Testing" by V.E. Lysaght, p.134For 82 < Rockwell B < 100For 10 < Rockwell C < 40Tensile strength (psi) = (4750000 - 12000 Rockwell B) / (130 - Rockwell B)
For Brinell < 175Tensile strength (psi) = 105 (7000 - 10 Rockwell C) / (100 - Rockwell C)2
For Brinell > 175Tensile strength (psi) = 515 Brinell
Tensile strength (psi) = 490 Brinell
Depth of Penetration to Hardness
from "The Rockwell Hardness Test" by D.C. Van AkenRockwell B = 130 - depth of penetration (mm) / 2 mmRockwell C = 100 - depth of penetration (mm) / 2 mm