Hardness Conversion Table: HRC, HB and HV for Steel
Drawings call out one hardness scale and the available tester measures another. This reference gives approximate equivalents between Rockwell C, Vickers and Brinell for steel so you can plan testing, review certificates and read supplier documents.
| Rockwell C (HRC) | Vickers (HV) | Brinell (HBW 10/3000) | Typical steel condition |
|---|---|---|---|
68 | 940 | n/a | Extreme hardness, hard-wearing tool steels, carbide range |
65 | 832 | 739 | Cold work tool steels at full hardness |
62 | 746 | n/a | High-speed steel cutters, bearing races |
60 | 697 | 654 | Bearing steel 52100 hardened, files |
55 | 595 | 560 | Hardened gears, die components |
50 | 513 | 481 | Hardened and tempered alloy steel shafts |
45 | 446 | 421 | Quenched and tempered 4140 high strength bolts |
40 | 392 | 371 | Quenched and tempered alloy steel, pre-hardened mold steel |
35 | 345 | 327 | Tempered alloy steel, crankshaft range |
30 | 302 | 286 | Tempered medium carbon steel, machinable high strength |
25 | 266 | 253 | Normalized or lightly tempered medium carbon steel |
20 | 238 | 226 | Annealed to normalized alloy steel, lower end of HRC scale |
Values follow the style of ASTM E140 conversion tables for non-austenitic steels and are approximate. Conversions between scales are empirical and carry scatter. Do not use them to accept or reject material when a contract specifies a particular scale. Convert only when a direct test is impractical, and state the method on the report.
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How to use the table
Find the hardness value you have in the HRC column, or search by an HV or HBW number. Read across for the other scales and a typical condition so you can sense-check the result. If a certificate lists 286 HBW and the drawing wants HRC, the table points to roughly HRC 30. Always keep the original reading and scale on the report; the converted value is a courtesy figure, not a measurement.
- Search by number to find the nearest row
- Interpolate linearly between rows for rough estimates
- Brinell is not defined above about HRC 60 in common practice
- Keep the originally specified scale on inspection records
The method and its limits
ASTM E140 publishes conversion tables built from comparative testing, and ASTM A370 references them for steel products. Rockwell measures indent depth under a major load, Vickers measures indent diagonal under a diamond pyramid, and Brinell measures a ball indent diameter. The scales respond differently to work hardening, microstructure and surface finish, so conversions are only valid for the material class tested. Austenitic stainless, copper alloys and aluminum each need their own tables.
Reading results in practice
Case-hardened parts require a micro-hardness scale such as HV 0.5 across the case depth, and a surface HRC test can be misleading because the thin case may not support the major load. For thin sections use superficial Rockwell scales. As a rough guide, tensile strength in MPa is often estimated at about 3.3 times HV for medium carbon steel, but that is a shop rule of thumb and not a certified value.
- Use HV for thin sections and case depth profiles
- Use HBW for castings and coarse-grained structures
- Use HRC for finished hardened parts on the shop floor
- Do not convert hardness on nitrided or plated surfaces
Common mistakes
Common errors include converting hardness values from stainless or aluminum using a steel table, treating converted numbers as measured acceptance data, and mixing HBS (steel ball) with HBW (tungsten carbide ball) readings. In an ERP quality module, store the measured value and its scale as separate fields, then keep any converted value in a comment rather than in the inspection result.
Frequently Asked Questions
How accurate is a hardness conversion?
Conversions are approximate and can differ by a point or more on the HRC scale depending on steel type and heat treatment. They are fine for estimation and cross-checking but not for contractual acceptance.
What is HRC 40 in Brinell?
Roughly 371 HBW on a 10 mm ball with a 3000 kgf load for non-austenitic steel, and about 392 HV. Treat it as an estimate and confirm with a direct test if the part is critical.
Why does the Brinell column stop around HRC 65?
At very high hardness a steel or even carbide ball can deform or fail to leave a measurable indent, so Brinell is not a practical method there. Rockwell or Vickers is preferred for hard parts.
Can I use this table for stainless steel?
Not reliably. Austenitic stainless work hardens strongly and has a different response across scales. Use the table in ASTM E140 for the right material group, or measure directly in the specified scale.
If you want hardness results from lab certificates captured into your ERP quality records, Netray can help automate that extraction on-prem. Ask for a short review.
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