Rockwell Blocks | Diameter | Nominal Hardness Values | Variation | NIST Traceable |
HRA | 64mm | 56, 65, 71, 75, 78, 81, 83, 85, 87 | +/-0.3 | No |
HRB | 64mm | 32, 42, 52 | +/-0.5 | No |
HRB | 64mm | 62, 72, 82, 90, 95, 100 | +/-0.4 | No |
HRC | 64mm | 10, 20, 25, 30, 35, 40 | +/-0.15 | Yes |
HRC | 64mm | 45, 50, 55, 60, 62, 64, 67, 70 | +/-0.1 | Yes |
HR15N | 64mm | 75, 80, 85, 87, 90, 92 | +/-0.45 | No |
HR30N | 64mm | 41, 50, 60, 67, 73, 78, 81, 83 | +/-0.5 | No |
HR15T | 64mm | 78, 82, 87 | +/-0.5 | No |
HR30T | 64mm | 32, 42, 52, 62, 72, 78 | +/-0.5 | No |
HRE | 64mm | 90 | +/-0.5 | No |
HRL | 64mm | 92, 118 | +/-0.5 | No |
HRM | 64mm | 67, 107 | +/-0.5 | No |
HRR | 64mm | 105, 123 | +/-0.5 | No |