This Technical Report establishes a European grouping system for materials for welding purposes, classified in accordance with the grouping system of ISO/TR 15608. It is also applicable for other purposes such as heat treatment, forming and non-destructive testing. This Technical Report covers grouping systems for the following standardized materials: a) steel; b) aluminium and its alloys; c) copper and its alloys; d) cast irons. In case of dispute, for example where variations in properties such as thickness and yield strength occur, ISO/TR 15608 applies.