Overview
EN ISO 22826:2021 (identical to ISO 22826:2005) defines requirements for destructive hardness testing of transverse sections of narrow laser- and electron-beam welded joints in metallic materials. The standard covers microhardness measurement using Vickers (HV) and Knoop (HK) methods with specified test-force ranges, specimen preparation rules, test locations and reporting requirements. It is intended for welded joints made with or without filler wire and is not generally applicable to wider hybrid laser/arc welds.
Key topics and technical requirements
- Scope of tests
- Hardness testing of weld metal, heat-affected zone (HAZ) and parent metal on transverse sections of narrow laser/electron-beam welds.
- Preferable ambient testing temperature: (23 ± 5) °C; report if outside this range.
- Tests must be performed in a vibration-free location.
- Hardness methods and force ranges
- Vickers (ISO 6507-1): test forces from 0.098 N to just under 98 N (HV 0.01 to just under HV 10).
- Knoop (ISO 4545): test forces up to and including 9.8 N (just under HK 1).
- Test types and locations
- Two principal test types: Type E (individual indentations) and Type R (rows of indentations); operator selects the type unless specified otherwise.
- For plate thickness or penetration depth t/h ≤ 4 mm: indentations placed at the mid-thickness (t/2 or h/2).
- For t or h > 4 mm: indentations located within 2 mm of top and bottom surfaces (or penetration boundaries).
- Specimen preparation
- Cross-section taken by mechanical cutting transverse to the joint; avoid heating that alters hardness.
- Surface preparation and optional etching per ISO/TR 16060 to permit accurate diagonal measurements.
- Reporting
- Record test type (E or R), hardness values for weld, HAZ and parent metal, test force, specimen orientation and environmental conditions.
Applications and users
- Practical use in weld quality control, metallurgical characterization and failure analysis for narrow laser and electron-beam welds.
- Typical users: welding inspectors, metallurgists, laboratory technicians, quality/assurance engineers and OEMs that specify microhardness criteria for precision welded components.
- Useful where evaluation of microhardness gradients across weld, HAZ and parent material is required (e.g., high-precision assemblies).
Related standards
Keywords: EN ISO 22826:2021, Vickers hardness, Knoop hardness, laser welded joints, electron beam welding, microhardness testing, weld HAZ testing, weld hardness standard.