A: One Rockwell number represents a penetration of 0.002mm (0.000080 in.)
Therefore, a reading of HRC 60 indicates a penetration from minor to major load of (100 - 60) X 0.002mm = 0.080 mm or 0.0032 in. A reading of HRB 80 indicates a penetration of (130 - 80) X 0.002 mm = 0.100 mm or 0.004in. Note: The numbers 100 and 130 above are the infinite hardness numbers for those scales. |