ISO/TR 945-3:2016 gives the designations, descriptions and reference micrographs of the matrix structures of cast irons. It applies to the following types of cast irons: - grey cast irons (Table 4.1); - spheroidal graphite cast irons (Table 4.2); - austenitic cast irons (Table 4.3); - malleable cast irons (Table 4.4); - compacted (vermicular) graphite cast irons (Table 4.5); - ausferritic spheroidal graphite cast irons (Table 4.6); - abrasion-resistant cast irons (Table 4.7). Each matrix structure is defined with explanations and micrographs. Unless otherwise stated in Clause 4, the micrographs shown correspond to samples etched with a solution of 2 % nitric acid in ethanol (Nital).