Select the Right Hardness Scale for Your Metal

• Start with the scale named in the specification or acceptance document — that is the scale your certificate has to speak.
• If field work forces a portable Leeb method, decide whether a converted value is acceptable, or whether a laboratory HRC/HV must remain the reference.
• Never treat a converted portable value as interchangeable with a direct laboratory measurement unless the procedure explicitly allows it — many specifications disallow it.

The portable instruments report native HL and convert across the common scales — match the material group correctly before trusting the converted number:

• Time 5150 — reads HL and converts to HRC, HRB, HRA, HV, HB and HS, covering most steel and alloy reporting needs from one compact tester.
• Impact (TIME 5100 series) — the same scale coverage with a choice of impact device (D, C or DL), useful when specimen mass varies across the parts you certify.

• Coarse-grained castings and forgings: a large-indent method such as Brinell averages out the microstructure that a small Leeb footprint can misread — note this where the specification allows only a direct scale.
• Cross-family conversions (a steel table applied to brass or a nickel alloy) are invalid — select the correct material group, and flag the value as converted on the report.

If the instrument choice is still open, continue to Choose a Portable Metal Hardness Tester.

• Metal Hardness Scale Conversions — the conversion tables, their limits and how to report a converted value.
• Leeb Rebound Hardness — what the native HL value represents.
• Portable Metal Hardness Testing — the field factors that affect the value before any conversion.