This Technical Report provides a uniform system for grouping of materials for welding purposes. It can also apply to other purposes, such as heat treatment, forming and non-destructive testing.This Technical Report covers grouping systems for the following standardized materials:— steels;— aluminium and its alloys;— copper and its alloys;— nickel and its alloys;— titanium and its alloys;— zirconium and its alloys;— cast irons.