HV
446
HB
421
HRB
–
Tensile (approx.)
1470 MPa
"–" means that scale is not used at this hardness.
The hardness scales
- Rockwell C (HRC): a diamond cone pressed in; used for hardened steel, about 20–68 HRC
- Rockwell B (HRB): a steel ball; used for soft steel, brass and aluminium
- Brinell (HB): a large ball leaves a wide dent; good for castings, forgings and soft to medium steel
- Vickers (HV): a small diamond pyramid; works on every hardness, thin layers and case depth
Hardness conversion table for steel
| HRC | HV | HB | HRB |
|---|---|---|---|
| 68 | 940 | – | – |
| 65 | 832 | – | – |
| 62 | 746 | – | – |
| 60 | 697 | 654 | – |
| 58 | 653 | 615 | – |
| 55 | 595 | 560 | – |
| 52 | 544 | 512 | – |
| 50 | 513 | 481 | – |
| 48 | 484 | 456 | – |
| 45 | 446 | 421 | – |
| 42 | 412 | 390 | – |
| 40 | 392 | 371 | – |
| 38 | 372 | 353 | – |
| 35 | 345 | 327 | – |
| 32 | 318 | 301 | – |
| 30 | 302 | 286 | – |
| 28 | 286 | 271 | – |
| 25 | 266 | 253 | – |
| 22 | 248 | 237 | – |
| 20 | 238 | 226 | 98 |
| – | 219 | 209 | 95 |
| – | 192 | 185 | 90 |
| – | 171 | 164 | 85 |
| – | 152 | 146 | 80 |
| – | 137 | 131 | 75 |
| – | 125 | 121 | 70 |
| – | 116 | 111 | 65 |
| – | 110 | 107 | 60 |
Approximate values for carbon and alloy steels. Brinell above about 450 HB is measured with a tungsten carbide ball and is not used above about 650 HB.
Questions
- How do you convert HRC to HB?
- Use a conversion table for steel: for example about 30 HRC ≈ 286 HB, 40 HRC ≈ 371 HB and 50 HRC ≈ 481 HB. The converter above interpolates between the table values.
- Are hardness conversions exact?
- No. Each test measures hardness differently, so conversions are approximate and valid only for similar materials (here, carbon and alloy steels). When it matters, test on the scale the drawing asks for.
- Which hardness scale should I use?
- Rockwell C for hardened steel (above about 20 HRC), Brinell or Rockwell B for softer steel, castings and forgings, and Vickers for thin layers, small parts and case depth.
- How is tensile strength estimated from hardness?
- For steels, tensile strength in MPa is roughly 3.3 × the Vickers hardness (or about 3.4 × Brinell). It is a rough guide only, not a replacement for a tensile test.
Hardening a part? See hardening and tempering, case carburising and nitriding.
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Get startedConversions between hardness scales are approximate and depend on the material. Use them for estimating; where a drawing specifies a scale, test on that scale.