Overview
ISO 6507-2:2018 - "Metallic materials - Vickers hardness test - Part 2: Verification and calibration of testing machines" specifies methods to verify and calibrate Vickers hardness testing machines and the diagonal measuring system used to determine Vickers hardness values (as defined in ISO 6507-1). The standard defines both a direct calibration route (test force, indenter geometry, diagonal measuring system, testing cycle) and an indirect route using reference blocks for overall machine checking. It applies to bench and portable hardness testing machines, but not to systems using different measurement principles (e.g., ultrasonic impedance).
Key Topics and Requirements
- Direct verification: calibration of the test force, indenter verification, calibration/verification of the diagonal measuring system, and testing cycle timing.
- Test force calibration: each force in the machine working range must be measured (at multiple plunger positions if force varies); acceptable methods include elastic proving devices per ISO 376 (class 1) or calibrated masses. Readings must meet specified maximum permissible relative errors.
- Indenter requirements: diamond pyramid faces must be polished and within geometric tolerances (face angle 136° ± 0.5°; opposite-edge angle 148.11° ± 0.76°). Length of the line of junction at the tip and angular misalignment limits are defined; a valid calibration certificate for the indenter is required.
- Diagonal measuring system: calibration for each magnification and scale orientation using a stage micrometer; uncertainties and maximum permissible measurement errors are specified (e.g., stage micrometer expanded uncertainty ≥ greater of 0.0004 mm or 0.2%).
- Testing cycle and environment: timing tolerances for load application/removal per ISO 6507-1; recommended verification temperature (23 ± 5) °C and traceability of instruments to national standards.
- Uncertainty and reporting: uncertainty of calibration/verification must be determined (Annex A provides guidance); verification reports / calibration certificates shall document results and reference-block hardness values.
Applications - Who Uses ISO 6507-2:2018
- Metallurgical and materials testing laboratories that perform Vickers hardness testing and require traceable, accredited calibration.
- Quality assurance and manufacturing teams using hardness testing for incoming inspection, heat-treatment verification, or process control.
- Calibration service providers and national metrology institutes performing machine and indenter calibrations.
- Users of portable Vickers hardness testers who need guideline conformity for on-site verification.
Related Standards
- ISO 6507-1 - Vickers hardness test - Test method (use in conjunction)
- ISO 6507-3 - Calibration of reference blocks (used for indirect verification)
- ISO 376 - Calibration of force‑proving instruments
Keywords: ISO 6507-2:2018, Vickers hardness test, verification and calibration, testing machines, diagonal measuring system, indenter verification, reference blocks, ISO 6507-1, ISO 6507-3, ISO 376, measurement uncertainty.
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