Overview
EN ISO 16859-1:2015 - "Metallic materials - Leeb hardness test - Part 1: Test method" specifies the standardized procedure for determining the dynamic (Leeb) hardness of metallic materials. The standard covers measurements on seven Leeb scales: HLD, HLS, HLE, HLDL, HLD+15, HLC, HLG, and defines the test principle, instrument requirements, specimen preparation, test procedure, and reporting.
Key topics and technical requirements
- Principle: A moving impact body strikes the surface and rebounds. Leeb hardness HL is calculated from impact (vA) and rebound (vR) velocities:
- HL = 1000 · (vR / vA) - a dimensionless hardness number.
- Leeb scales: Different impact devices/types produce different HL values; the scale (e.g., HLD, HLC) must be reported with results.
- Testing instrument:
- Impact device (spherical indenter) plus electronic unit to measure vA and vR.
- Support ring and indenter materials specified; instrument verification per ISO 16859-2.
- Test piece requirements:
- Shape: local surface must allow impact velocity normal to surface; curved surfaces allowed with minimum radii (documented limits).
- Minimum mass and thickness requirements (by impact device type) to ensure stiffness and valid results - e.g., types D/DL/D+15/S/E: uncoupled minimum mass 5 kg and minimum thickness 25 mm (see Table 2 for other types).
- Surface preparation to avoid heat- or work-induced hardness changes.
- Corrections & uncertainty:
- Corrections for tests not conducted in the direction of gravity (Annex A).
- Procedures for periodic checking/verification by the user (Annex B).
- Guidance on uncertainty of measured Leeb values (Annex C).
- Reporting: Test direction, device type (scale), any corrections, and uncertainty must be recorded. Conversions to other hardness or tensile values are addressed.
Practical applications and users
EN ISO 16859-1:2015 is widely used for rapid, portable hardness screening and quality control where:
- In-service or large components cannot be sectioned (welds, shafts, forgings).
- Production inspection of steel and other metals (incoming material checks, heat treatment verification).
- Field and workshop testing by metallurgists, quality engineers, maintenance technicians, and non-destructive testing (NDT) professionals.
- Calibration and verification activities (in conjunction with ISO 16859-2 and ISO 16859-3 for devices and reference blocks).
Related standards
- ISO 16859-2 - Verification and calibration of Leeb testing devices.
- ISO 16859-3 - Calibration of reference test blocks.
- National adoption: EN ISO 16859-1:2015 (CEN) - implemented as a national standard across CEN member countries.
Keywords: EN ISO 16859-1:2015, Leeb hardness, Leeb scales, metallic materials, dynamic hardness test, impact device, hardness testing method, portable hardness testing.