Metal Hardness HRC, HV, HB — Meaning & How to Measure

Hardness is a material’s resistance to indentation. An indenter is pressed into the surface at a set load, then the size or depth of the mark is measured.

It correlates with wear resistance and strength, so it is the key number customers use to accept hardened parts.

• HRC (Rockwell C) — the most common for hardened steel; fast and easy over 20–65 HRC; used on screws, nuts and bolts.
• HV (Vickers) — a diamond pyramid indenter measures from very thin surfaces to very hard parts; ideal for case-depth profiling.
• HB (Brinell) — a hard ball on softer/medium material leaves a large mark; suited to castings and raw steel.

Approximate conversion tables exist (e.g. ASTM E140), but they are estimates and should not replace real measurement on precision work.

Watch out: plated surfaces, decarburized skins or parts that are too thin can skew readings. Prepare the surface and pick the right scale.

Good hardening comes with a test report stating actual hardness, number of points measured and accepted limits.

The V.S. Heat Treatment lab uses a Vickers Hardness Test (HV) — a diamond pyramid indenter read under a microscope for high precision — plus an X-ray coating-thickness gauge resolving down to 0.3 mm per point, and issues a report with every lot under ISO 9001:2015.