ISO 4545-2:2017

Overview

ISO 4545-2:2017 - "Metallic materials - Knoop hardness test - Part 2" specifies procedures for the verification and calibration of Knoop hardness testing machines used on metallic materials. It defines both a direct method (calibration of test force, indenter geometry, and diagonal-length measuring system) and an indirect method (overall performance check using calibrated reference blocks). The standard requires traceability to national standards and documents results in a verification report or calibration certificate.

Key topics and requirements

• Scope and conditions
  • Applies to Knoop hardness testing in accordance with ISO 4545-1.
  • Verifications should normally be performed at (23 ± 5) °C and instruments must be traceable.
• Direct verification (Clause 5)
  • Test force calibration: measure each force across the machine’s force range; use an elastic proving device in accordance with ISO 376:2011 (class 1) or balanced calibrated masses (±0.2% accuracy). Specific maximum permissible relative errors are defined by force ranges.
  • Indenter verification: geometric checks (polished faces; angles and alignment). Example tolerances: angle α = 172.5° ± 0.1°, angle β = 130° ± 1.0°, indenter constant c within ±1.0% of 0.07028, axis misalignment ≤ ±0.5°, line-of-junction