Overview
ISO 16859-2:2015 specifies verification and calibration methods for instruments that perform the Leeb hardness test on metallic materials. It defines both direct verification (checking individual instrument parameters) and indirect verification (checking overall instrument performance using calibrated reference test blocks). The standard sets procedural requirements, environmental conditions and reporting expectations to ensure traceable, repeatable Leeb hardness measurements.
Key topics and requirements
- Verification types
- Direct verification: inspection and measurement of individual components and parameters such as impact-body mass and geometry, indenter ball geometry and hardness, support-ring thickness, and impact velocity (measured in the direction of gravity).
- Indirect verification: overall performance check using reference test blocks (calibrated per ISO 16859-3). The indirect method can be used alone for periodic in-service checks.
- Environmental and procedural conditions
- Recommended temperature: (23 ± 5) °C for verifications (must be reported if outside this range).
- Instruments must be set up per manufacturer instructions before verification.
- Measurement procedure
- Use three reference test blocks covering different hardness ranges and make 10 indentations on each block, uniformly distributed and tested in the direction of gravity (per ISO 16859‑1 test method).
- Calculate the variation coefficient (V) from the 10 readings and the error (E) relative to the certified value of the reference block. Permissible limits are specified in the standard (see Table 3).
- Traceability and uncertainty
- Verifying instruments and blocks must be traceable to national measurement standards. The standard addresses measurement uncertainty considerations and reporting requirements for calibration certificates.
Practical applications and users
- Calibration laboratories and metrology services performing instrument certification and issuing calibration certificates.
- Manufacturers of Leeb hardness testers for quality assurance of impact devices and components.
- Quality control and inspection teams in metalworking, heat treatment, forging, and fabrication who rely on portable hardness testing in the field.
- Maintenance and service technicians who perform periodic in-service verification and troubleshooting of portable Leeb testers.
Related standards
- ISO 16859-1: Leeb hardness test - Test method (required for performing tests)
- ISO 16859-3: Calibration of reference test blocks (used for indirect verification)
- ISO 6507-1: Vickers hardness test - referenced for indenter hardness checks
Keywords: ISO 16859-2:2015, Leeb hardness test, verification, calibration, reference test blocks, impact device, indirect verification, direct verification, measurement uncertainty.