Overview
CEN ISO/TR 20172:2021 - “Welding - Grouping systems for materials - European materials” - is a CEN-endorsed ISO Technical Report that establishes a European material grouping system for welding purposes. It aligns European material designations with the international grouping framework of ISO/TR 15608 and covers standardized materials including steel, aluminium and its alloys, copper and its alloys, cast irons, and nickel and nickel alloys. The report is intended for use in welding, and also supports related activities such as heat treatment, forming and non-destructive testing (NDT).
Key Topics
- Material grouping methodology: Classification of European materials into groups/sub-groups based on the ISO/TR 15608 grouping concept (chemical composition and mechanical properties).
- Comprehensive tables: Tabulated listings (revised Tables 1–5 and a new Table 6 for nickel alloys) that map European designations and EN standard references to grouping categories.
- Cross‑reference to EN standards: Each listed material links to relevant EN specifications (for example EN 10216, EN ISO 683 series), enabling traceability to standard material definitions and supply conditions.
- Guidance on applicability: Notes that materials with delivering conditions outside ISO/TR 15608 limits may behave differently during welding and therefore welding conditions should be specifically adapted.
- Fallback criteria: For materials not listed, the grouping criteria of ISO/TR 15608 apply.
Applications
CEN ISO/TR 20172:2021 is practical for tasks where consistent material grouping is required:
- Selection of welding consumables and filler metals aligned to the parent material group.
- Preparation and qualification of welding procedures (WPQR/WPS) and procedure specifications.
- Planning pre-/post-heat treatment and forming operations by understanding group-related behaviour.
- Non-destructive testing (NDT) strategy development where material grouping influences inspection regimes.
- Materials management and procurement - matching purchased European materials to appropriate welding and fabrication practices.
Who would use this standard
- Welding engineers and procedure writers
- Quality assurance / welding inspectors and NDT technicians
- Fabrication and manufacturing engineers
- Material suppliers and purchasers
- Standards committees and certification bodies
Related Standards
- ISO/TR 15608 - international grouping system for welding purposes (primary classification basis)
- ISO/TR 20173:2018 and ISO/TR 20174:2020 - complementary material grouping guidance for materials not listed
- Relevant EN material standards referenced in the tables (e.g., EN 10216, EN ISO 683 series)
Using CEN ISO/TR 20172:2021 helps ensure consistent, standards‑based material grouping across Europe - improving welding consumable selection, procedure qualification, and downstream processing decisions.
