Overview
ISO 23718:2007 - Metallic materials - Mechanical testing - Vocabulary defines the standardized terminology used in mechanical testing of metals. Published in 2007 by ISO/TC 164, this International Standard provides a common basis for laboratory procedures, test standards and technical communication by offering clear, unambiguous definitions of terms used across uniaxial testing, ductility, hardness, toughness (including Charpy and fracture toughness) and fatigue testing.
Key topics
The standard organizes terms into focused sections and key technical topics:
- General terms: crack growth, crack length/size, ductility, elastic limit, force, mechanical properties.
- Uniaxial testing vocabulary: engineering vs true stress and strain, modulus of elasticity (Young’s modulus), Poisson’s ratio, axial/transverse strain.
- Ductility and hardness terms: definitions used to describe plastic deformation and hardness test concepts.
- Toughness testing: vocabulary for Charpy impact tests and fracture toughness (CT, MT specimens and crack tip terminology are referenced).
- Fatigue testing terms: crack propagation, Δa (change in crack length), stress/strain range and related fatigue vocabulary.
- Practical notes: units (e.g., crack length expressed in millimetres), alphabetical index and bilingual presentation (English/French).
The document does not prescribe test procedures or numerical acceptance criteria; its role is to harmonize language so different standards and technical documents are consistent.
Applications and users
ISO 23718:2007 is useful for:
- Materials and metallurgical engineers ensuring consistent interpretation of test reports and literature.
- Test laboratories and quality assurance teams that perform tensile, hardness, impact, fracture toughness and fatigue tests.
- Standards developers and technical committees who reference consistent terminology across new or revised test standards.
- Researchers and educators preparing teaching materials and technical publications (terms and definitions may be reproduced for educational or implementation use with citation).
- Procurement and regulatory professionals who specify mechanical testing requirements in contracts and certifications.
Using ISO 23718 helps reduce ambiguity in test reports, improves communication between labs and clients, and supports reliable comparison of mechanical property data.
Related standards
- ISO 23718:2007 supersedes ISO/TR 12735-1:1996 (technical revision).
- Prepared by ISO/TC 164 (Mechanical testing of metals); consult other ISO standards on specific test methods (tensile, Charpy, fracture toughness, hardness and fatigue) for procedural and acceptance criteria.
Keywords: ISO 23718, mechanical testing vocabulary, metallic materials, fracture toughness, Charpy impact, fatigue testing, modulus of elasticity, engineering stress strain.
