Metal Hardness Conversion Chart
Approximate equivalent hardness numbers for steel based on SAE J417 and ASTM E140 standards. Values are correlated with approximate tensile strength.
| Approx. Tensile Strength | Rockwell C (HRC) | Rockwell B (HRB) | Brinell (HBW) | Vickers (HV) |
|---|---|---|---|---|
| 285,000 psi | 55 | - | 600 | 640 |
| 243,000 psi | 50 | - | 481 | 513 |
| 212,000 psi | 45 | - | 421 | 446 |
| 181,000 psi | 40 | - | 371 | 392 |
| 153,000 psi | 33 | 109 | 311 | 327 |
| 128,000 psi | 26 | 102 | 258 | 272 |
| 108,000 psi | 15 | 94 | 217 | 228 |
| 85,000 psi | - | 82 | 158 | 165 |
| 71,000 psi | - | 71 | 130 | 136 |
Understanding the Scales
- Rockwell C (HRC): Uses a diamond cone indenter. Standard for hard steels, tooling, and high-strength fasteners (Grade 8 / Class 10.9+).
- Rockwell B (HRB): Uses a 1/16" steel ball indenter. Standard for softer metals like brass, aluminum, and mild steel.
- Brinell (HBW): Uses a large tungsten carbide ball. Great for castings and forgings where the material might not be perfectly uniform.