Overview
ISO 23598:2021 defines specimen geometry and a standardized procedure for mechanized peel testing of single mechanical joints in sheet materials (including extrusions and castings) up to a single sheet thickness of 4.5 mm. The standard is intended to determine the mechanical characteristics and failure modes of single-lap mechanical joints produced by different joining methods. It excludes civil engineering structural applications and points users to ISO 14270 for resistance spot, seam and embossed projection weld testing.
Key topics and technical requirements
- Specimen geometry and tolerances: Specifies test coupon and single-lap specimen shapes, flange lengths, bend radii and clamping distances so results are reproducible for sheets ≤ 4.5 mm.
- Bending / preparation sequence: Recommends a “joining-after-bending” sequence (Bending → Mechanical joining → Mechanized peel testing). Notes exceptions (e.g., bending-after-welding for some resistance-spot welds).
- Bend radius guidance: Inner bend radius should avoid visible cracking; an inner radius of approximately 2 × thickness (2t) is recommended and must be recorded. If cracking occurs, radius must be increased and retested.
- Testing equipment and measurement: Requires a calibrated tensile testing machine meeting ISO 7500-1. Force and crosshead displacement must be measured simultaneously (force accuracy ±1 %). Crosshead speed should be ≤ 10 mm/min and recorded. Displacement may be corrected for machine stiffness or measured directly at the specimen.
- Recorded metrics: Mechanized peel strength (MPS / Fmax), specimen deformation at key points, slippage force (if present), and dissipated energy up to defined points on the load–displacement curve. Slippage is reported and affects energy calculations.
- Failure classification and retest rules: Failure modes are classified per the annex; if fracture originates from the bent corner, results are invalid and specimens must be remade with larger radii.
Applications and who uses this standard
ISO 23598:2021 is practical for:
- Materials/Joining engineers developing and validating mechanical joining methods and fasteners.
- Quality assurance and test laboratories performing destructive testing for supplier validation and production control.
- R&D teams assessing joint strength, failure modes and energy absorption.
- Manufacturers in automotive, aerospace and light engineering where sheet joining is critical for performance and safety.
Use cases include process development, comparison of joining technologies, supplier specifications and contract testing.
Related standards
- ISO 14270 - mechanized peel testing for resistance spot, seam and embossed projection welds.
- ISO 7500-1 - calibration and verification of force-measuring systems on uniaxial testing machines.
Keywords: ISO 23598, mechanized peel testing, mechanical joining, sheet materials, specimen dimensions, peel force, bend radius, tensile testing machine, failure modes.