ISO 21224:2025

Evaluation of centreline segregation of continuously cast slabs ISO 21224:2025

Publication date:   Dec 12, 2025

Scope

This document specifies a procedure for the evaluation of centreline segregation of continuously cast slabs, including sampling, sample preparation and evaluation method.
This document is applicable for low carbon steel slabs for pipe production manufactured by continuous casting. These steels have a typical chemical composition as follows (mass percentages):
—     C ≤ 0,12 %
—     Mn ≤ 2,0 %
—     Si ≤ 0,5 %
—     Ti + Nb + V ≤ 0,2 %
The common dimensions of these slabs are in the following ranges:
—     Slab width: 800 mm to 2 600 mm
—     Slab thickness: 150 mm to 450 mm
The evaluation methods covered by this document are based on macroscopic etching of slab samples followed by visual inspection by means of human eye or camera systems.
The procedures for sampling described in 5.1 to 5.3 of this document are applicable to steels slabs in general (e. g. other steel grades or dimensions). However, the etching procedure (see 5.4) in combination with the evaluation methods described in Clause 6 have been developed especially for the application on pipeline steels as given above. Thus, they are not applicable to other steel grades, product types or dimensions without a prior validation. Any extension or modification beyond the scope of this document necessitates a separate agreement between producer and customer.