Hardness conversion chart — steel
Rockwell C, Vickers, Brinell and approximate tensile strength, from the published ASTM E140 anchors — including where the standards say a scale stops being valid.
| Rockwell C | Vickers HV | Brinell HBW | Approx. tensile (MPa) | Typical material |
|---|---|---|---|---|
| 20 | 238 | 226 | 750 | Mild steel, annealed |
| 25 | 266 | 253 | 855 | Normalised EN8 |
| 30 | 302 | 286 | 965 | EN8 / EN3 heat treated |
| 35 | 345 | 327 | 1105 | EN19 quenched & tempered |
| 40 | 392 | 371 | 1255 | EN24 Q&T, 17-4 PH H1025 |
| 45 | 446 | 421 | 1420 | Hardened alloy steel, 17-4 PH H900 |
| 50 | 513 | 481 | 1605 | Tool steel, 440C hardened |
| 55 | 595 | 560 | 1890 | D2 / H13 hardened |
| 60 | 697 | beyond range | 2205 | M2 HSS |
| 65 | 832 | beyond range | none published | File-hard, nitrided case |
These are correlations, not conversions. Each scale uses a different indenter and load, so treat any converted value as roughly ±5–10%. Where a specification names a scale, test in that scale.
Do not use this table for austenitic stainless, aluminium, copper alloys or cast iron. ASTM E140 publishes separate tables for each — using the steel table on them gives a plausible-looking wrong answer.
Why the gaps are blank. Brinell stops being valid above about 650 HBW (ASTM E10) because the ball itself deforms, and no tensile correlation is published at HRC 65. Most charts print numbers there anyway; we would rather leave it empty and say why.
Convert any value with the hardness conversion calculator.
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