The Vickers hardness test (HV) and Rockwell C hardness test (HRC) are the two most widely used hardness measurement methods in engineering. Converting between them is essential for comparing specifications written in different scales — for example, when a material spec calls for HRC 58–62 but your laboratory only has a Vickers tester, or when a weld spec limits HAZ hardness to 350 HV but the drawing specifies the component hardness in HRC. This dedicated HV ↔ HRC converter uses ASTM E140-12b tabulated data with polynomial curve fitting for accurate interpolation.
Vickers ↔ Rockwell C Hardness Converter
Conversion per ASTM E140-12b Standard Hardness Conversion Tables for Metals.
Valid for wrought carbon and alloy steels only. Not applicable to cast iron, non-ferrous alloys, case-hardened surfaces (use microhardness for case depth profiles), or coatings.
Accuracy: ±1–2 HRC or ±10–20 HV for most steel types within the applicable range.
ASTM E140 Hardness Conversion Quick Reference
| HRC | HV | HBW | Approx. UTS (MPa) | Typical Application |
|---|---|---|---|---|
| 68 | 940 | 895 | 3,090 | Maximum for steel; file-hard |
| 62 | 746 | 710 | 2,450 | As-quenched high-carbon steel |
| 58 | 633 | 603 | 2,080 | Case-hardened surface, bearing steel |
| 52 | 512 | 488 | 1,680 | Hardened H13 tool steel (tempered) |
| 45 | 432 | 411 | 1,420 | Austempered ductile iron (ADI) |
| 40 | 381 | 363 | 1,250 | Q&T S690 structural steel |
| 35 | 336 | 320 | 1,100 | Bainitic steels; hardened spring steel |
| 30 | 294 | 280 | 966 | NACE MR0175 max HAZ limit |
| 25 | 260 | 248 | 856 | Normalised 4140; annealed tool steel |
| 20 | 238 | 227 | 783 | Lower limit of HRC; above = use HRB |
Important Conversion Limitations
- Material-specific: ASTM E140 tables apply only to wrought carbon and low-alloy steels. Conversion for cast iron, non-ferrous alloys, stainless steels, and nickel alloys requires alloy-specific tables and will give inaccurate results if the standard tables are used.
- Surface condition: For case-hardened components, HRC measures the through-thickness average of a deep indent (1.5mm penetration) — not the surface case hardness. Use Vickers microhardness (HV0.1–HV1) for case hardness and depth profiling.
- Temperature: Hardness conversions are calibrated at room temperature (23°C ± 5°C). Elevated-temperature hardness testing uses specialised instruments and separate conversion data.
References
- ASTM E140-12b Standard Hardness Conversion Tables for Metals Relationship Among Brinell, Vickers, Rockwell, Superficial, Knoop, Scleroscope, and Leeb Hardness.
- ISO 18265:2013 Metallic materials — Conversion of hardness values.
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