ISO · 531 grades

ISO steel grades — 531 designations — Page 5

Every grade designated under ISO, with the material number it maps to, what kind of steel it is, its carbon window and how many other standards carry it. Open a grade for its full composition, properties and its designations in other standards. Every name on this page is an indicative cross-reference, not an asserted identity: the grades are close, not interchangeable. Check the composition before you substitute.

Also known as

531 designations

Grade	Material no.	Category	C% by weight	Also inother standards
C25	1.0406	Quenched and tempered steels	0.22–0.29	20
C25 C25E4 C25M2	1.0406	Quenched and tempered steels	0.22–0.29	20
C25 C25E4 C25M2	1.0415	Quenched and tempered steels	0.24–0.29	6
C25 C25E4 C25M2	1.1139	Quenched and tempered steels	0.24–0.29	6
C25 C25E4 C25M2	1.1158	Quenched and tempered steels	0.22–0.29	12
C25 C25E4 C25M2	1.1163	Quenched and tempered steels	0.22–0.29	6
C25 C25E4 C25M2	1.9415	Quenched and tempered steels	0.22–0.28	6
C25E4	1.1158	Quenched and tempered steels	0.22–0.29	12
C30	1.0528	Quenched and tempered steels	0.27–0.34	14
C30 C30E4 C30M2	1.0528	Quenched and tempered steels	0.27–0.34	14
C30 C30E4 C30M2	1.0530	Others	0.3–0.35	7
C30 C30E4 C30M2	1.1143	Quenched and tempered steels	0.3–0.34	7
C30 C30E4 C30M2	1.1178	Quenched and tempered steels	0.27–0.34	13
C30 C30E4 C30M2	1.1179	Quenched and tempered steels	0.27–0.34	8
C30 C30E4 C30M2	1.9416	Quenched and tempered steels	0.28–0.34	7
C30E	1.0528	Quenched and tempered steels	0.27–0.34	14
C30E4	1.0528	Quenched and tempered steels	0.27–0.34	14
C30E4	1.1178	Quenched and tempered steels	0.27–0.34	13
C35	1.0501	Quenched and tempered steels	0.32–0.39	23
C35E4	1.1181	Quenched and tempered steels	0.32–0.39	20
C35E4	1.0501	Quenched and tempered steels	0.32–0.39	23
C35M2	1.1180	Quenched and tempered steels	0.32–0.39	11
C40	1.0511	Quenched and tempered steels	0.37–0.44	21
C40 C40E4 C40M2	—	—	—	3
C40E4	1.0511	Quenched and tempered steels	0.37–0.44	21
C40E4	1.1186	Quenched and tempered steels	0.37–0.44	16
C40M2	1.1189	Quenched and tempered steels	0.37–0.44	8
C45	1.0503	Quenched and tempered steels	0.42–0.5	24
C45 C45E4 C45M2	—	—	—	3
C45E4	1.1191	Quenched and tempered steels	0.42–0.5	21
C45E4	1.1191	Others	0.42–0.5	18
C45M2	1.1201	Quenched and tempered steels	0.42–0.5	11
C50	1.0540	Quenched and tempered steels	0.47–0.55	13
C50	1.0535	Quenched and tempered steels	0.52–0.6	21
C50 C50E4 C50M2	1.0540	Quenched and tempered steels	0.47–0.55	13
C50 C50E4 C50M2	1.1171	Others	0.48–0.52	6
C50 C50E4 C50M2	1.1201	Quenched and tempered steels	0.42–0.5	11
C50 C50E4 C50M2	1.1206	Quenched and tempered steels	0.47–0.55	17
C50 C50E4 C50M2	1.9505	Others	0.46–0.53	6
C50 C50E4 C50M2	1.0586	Steels for surface hardening	0.48–0.53	7
C50 C50E4 C50M2	1.1213	Steels for surface hardening	0.5–0.57	11
C50 C50E4 C50M2	1.1241	Steels for surface hardening	0.47–0.55	8
C50 C50E4 C50M2	1.9505	Steels for surface hardening	0.48–0.55	6
C50E4	1.0540	Quenched and tempered steels	0.47–0.55	13
C50E4	1.1206	Quenched and tempered steels	0.47–0.55	17
C50M2	1.1241	Steels for surface hardening	0.47–0.55	8
C55	1.0535	Quenched and tempered steels	0.52–0.6	21
C55E4	1.1203	Quenched and tempered steels	0.52–0.6	15
C55E4	1.0535	Quenched and tempered steels	0.52–0.6	21
C55M2	1.1209	Others	0.52–0.6	8

This grade’s own name — recorded in our sources as this grade’s own designation under that standard.
Indicative — taken from a published cross-reference table; a close match, not a guarantee of interchangeability. Verify against the mill certificate before ordering.
Withdrawn — designation no longer current — a separate column from the two above, so a name can be same grade and withdrawn at once.