Overview
ISO/TR 23602:2005 - Toughness of chain steels is an ISO Technical Report that investigates and quantifies the material toughness required for the operational safety of round steel chains. The report is informative (not normative) and focuses on damaged (pre-cracked) chains tested under unfavourable conditions, including the lowest permissible operating temperature (notably −40 °C in the investigation). The work links tensile tests, notch-impact energy, fracture mechanics and practical acceptance criteria to provide a simple test-based approach for assessing chain material safety against brittle fracture.
Key topics and technical requirements
- Scope and objective: Define minimum material toughness needed to avoid brittle fracture in round steel chains under worst‑case service conditions.
- Materials and chain types: Study centered on 16 × 48 round link chains manufactured to ISO chain grades (Type T, TH, VH) with typical heat treatments and specified chemical compositions.
- Test methods used:
- Tensile tests on chain link specimens at room temperature and −40 °C.
- Notch impact (Charpy/C) tests and Crack Opening Displacement (COD) measurements.
- Fracture mechanics tests on notched three‑point bend (TPB) specimens, pre‑cracked specimens and notched chain links with slits.
- Finite element analysis to correlate stress intensity and nominal fracture stress.
- Fracture concepts:
- Development of load‑bearing vs brittle‑fracture transition concept.
- Correlation of chain fracture stress with fracture‑mechanics properties (K, J, R‑curves) and notch impact energy.
- Positioning of allowable operating temperature relative to the nil‑ductility temperature (NDT).
- Outcome: Derivation of minimum notch‑impact energy values and a straightforward test/acceptance procedure for chain materials and types based on combined fracture mechanics and impact test data.
Applications and who uses it
ISO/TR 23602:2005 is practical for:
- Chain manufacturers and heat‑treaters validating material toughness and production processes.
- Design and safety engineers specifying lifting and hoisting chains for low‑temperature service.
- Testing laboratories performing Charpy, COD and fracture‑mechanics qualification tests.
- Procurement and inspection authorities setting acceptance criteria to avoid brittle failure in service.
- Standards developers and technical committees harmonizing chain safety requirements.
Related standards (normative references)
Key referenced documents include:
- ISO 3077, ISO 16872, ISO 16877 (chain product standards)
- EN 10083‑3 (quenched & tempered steels)
- EN 10002 (tensile testing), EN 10045 (Charpy impact)
- BS 5762 (COD testing), ASTM E813, ASTM E399 (fracture toughness methods)
- DIN 17155 (steel for welded round links)
Keywords: ISO/TR 23602:2005, toughness of chain steels, round steel chains, fracture mechanics, notch impact energy, brittle fracture transition, nil‑ductility temperature, chain safety.