--- title: "ISO steel grades — 531 designations — Page 5" description: "Steel grades designated under ISO, with chemical composition, mechanical properties and equivalents in other standards. 531 designations across 327…" canonical: https://steelequivalents.com/materials/iso/page/5 language: en robots: index, follow og_type: website type: material-standard language_alternates: en: https://steelequivalents.com/materials/iso/page/5.md cs: https://steelequivalents.com/cs/materiály/iso.md de: https://steelequivalents.com/de/werkstoffe/iso.md es: https://steelequivalents.com/es/materiales/iso.md fr: https://steelequivalents.com/fr/matériaux/iso.md hu: https://steelequivalents.com/hu/anyagok/iso.md it: https://steelequivalents.com/it/materiali/iso.md nl: https://steelequivalents.com/nl/materialen/iso.md pl: https://steelequivalents.com/pl/materiały/iso.md pt: https://steelequivalents.com/pt/materiais/iso.md ru: https://steelequivalents.com/ru/материалы/iso.md tr: https://steelequivalents.com/tr/malzemeler/iso.md zh: https://steelequivalents.com/zh/材料/iso.md ja: https://steelequivalents.com/ja/材料/iso.md ar: https://steelequivalents.com/ar/المواد/iso.md ko: https://steelequivalents.com/ko/재료/iso.md pt-br: https://steelequivalents.com/pt-br/materiais/iso.md hi: https://steelequivalents.com/hi/सामग्री/iso.md content_hash: sha256:579a4e92530edd53a303d69021b2522c72d03675c1d68290de89a65bde4e54b7 generated: 2026-09-25 --- > **Machine-readable Markdown rendering.** This is a Markdown representation of a web page, > served for AI agents and crawlers as a token-efficient alternative to the full HTML. > Full interactive HTML version: https://steelequivalents.com/materials/iso/page/5 > Canonical URL: https://steelequivalents.com/materials/iso/page/5 > Available languages: en, cs, de, es, fr, hu, it, nl, pl, pt, ru, tr, zh, ja, ar, ko, pt-br, hi > Change detection: `content_hash` is the SHA-256 of this document's Markdown body — everything > below this block, whitespace-trimmed, excluding the front-matter. Compare it to detect a real > content change; `generated` moves on every render and is not a change signal. 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 in other standards | |---|---|---|---|---| | [C25](/materials/din-en/c25 "C25") | [1.0406](/materials/material-no/1.0406 "1.0406") | Quenched and tempered steels | 0.22–0.29 | 20 | | [C25 C25E4 C25M2](/materials/iso/c25-c25e4-c25m2 "C25 C25E4 C25M2") | [1.0406](/materials/material-no/1.0406 "1.0406") | Quenched and tempered steels | 0.22–0.29 | 20 | | [C25 C25E4 C25M2](/materials/iso/c25-c25e4-c25m2 "C25 C25E4 C25M2") | [1.0415](/materials/material-no/1.0415 "1.0415") | Quenched and tempered steels | 0.24–0.29 | 6 | | [C25 C25E4 C25M2](/materials/iso/c25-c25e4-c25m2 "C25 C25E4 C25M2") | [1.1139](/materials/material-no/1.1139 "1.1139") | Quenched and tempered steels | 0.24–0.29 | 6 | | [C25 C25E4 C25M2](/materials/iso/c25-c25e4-c25m2 "C25 C25E4 C25M2") | [1.1158](/materials/material-no/1.1158 "1.1158") | Quenched and tempered steels | 0.22–0.29 | 12 | | [C25 C25E4 C25M2](/materials/iso/c25-c25e4-c25m2 "C25 C25E4 C25M2") | [1.1163](/materials/material-no/1.1163 "1.1163") | Quenched and tempered steels | 0.22–0.29 | 6 | | [C25 C25E4 C25M2](/materials/iso/c25-c25e4-c25m2 "C25 C25E4 C25M2") | [1.9415](/materials/material-no/1.9415 "1.9415") | Quenched and tempered steels | 0.22–0.28 | 6 | | [C25E4](/materials/iso/c25e4 "C25E4") | [1.1158](/materials/material-no/1.1158 "1.1158") | Quenched and tempered steels | 0.22–0.29 | 12 | | [C30](/materials/din-en/c30 "C30") | [1.0528](/materials/material-no/1.0528 "1.0528") | Quenched and tempered steels | 0.27–0.34 | 14 | | [C30 C30E4 C30M2](/materials/iso/c30-c30e4-c30m2 "C30 C30E4 C30M2") | [1.0528](/materials/material-no/1.0528 "1.0528") | Quenched and tempered steels | 0.27–0.34 | 14 | | [C30 C30E4 C30M2](/materials/iso/c30-c30e4-c30m2 "C30 C30E4 C30M2") | [1.0530](/materials/material-no/1.0530 "1.0530") | Others | 0.3–0.35 | 7 | | [C30 C30E4 C30M2](/materials/iso/c30-c30e4-c30m2 "C30 C30E4 C30M2") | [1.1143](/materials/material-no/1.1143 "1.1143") | Quenched and tempered steels | 0.3–0.34 | 7 | | [C30 C30E4 C30M2](/materials/iso/c30-c30e4-c30m2 "C30 C30E4 C30M2") | [1.1178](/materials/material-no/1.1178 "1.1178") | Quenched and tempered steels | 0.27–0.34 | 13 | | [C30 C30E4 C30M2](/materials/iso/c30-c30e4-c30m2 "C30 C30E4 C30M2") | [1.1179](/materials/material-no/1.1179 "1.1179") | Quenched and tempered steels | 0.27–0.34 | 8 | | [C30 C30E4 C30M2](/materials/iso/c30-c30e4-c30m2 "C30 C30E4 C30M2") | [1.9416](/materials/material-no/1.9416 "1.9416") | Quenched and tempered steels | 0.28–0.34 | 7 | | [C30E](/materials/din-en/c30e "C30E") | [1.0528](/materials/material-no/1.0528 "1.0528") | Quenched and tempered steels | 0.27–0.34 | 14 | | [C30E4](/materials/iso/c30e4 "C30E4") | [1.0528](/materials/material-no/1.0528 "1.0528") | Quenched and tempered steels | 0.27–0.34 | 14 | | [C30E4](/materials/iso/c30e4 "C30E4") | [1.1178](/materials/material-no/1.1178 "1.1178") | Quenched and tempered steels | 0.27–0.34 | 13 | | [C35](/materials/din-en/c35 "C35") | [1.0501](/materials/material-no/1.0501 "1.0501") | Quenched and tempered steels | 0.32–0.39 | 23 | | [C35E4](/materials/iso/c35e4 "C35E4") | [1.1181](/materials/material-no/1.1181 "1.1181") | Quenched and tempered steels | 0.32–0.39 | 20 | | [C35E4](/materials/iso/c35e4 "C35E4") | [1.0501](/materials/material-no/1.0501 "1.0501") | Quenched and tempered steels | 0.32–0.39 | 23 | | [C35M2](/materials/iso/c35m2 "C35M2") | [1.1180](/materials/material-no/1.1180 "1.1180") | Quenched and tempered steels | 0.32–0.39 | 11 | | [C40](/materials/din-en/c40 "C40") | [1.0511](/materials/material-no/1.0511 "1.0511") | Quenched and tempered steels | 0.37–0.44 | 21 | | [C40 C40E4 C40M2](/materials/iso/c40-c40e4-c40m2 "C40 C40E4 C40M2") | — | — | — | 3 | | [C40E4](/materials/iso/c40e4 "C40E4") | [1.0511](/materials/material-no/1.0511 "1.0511") | Quenched and tempered steels | 0.37–0.44 | 21 | | [C40E4](/materials/iso/c40e4 "C40E4") | [1.1186](/materials/material-no/1.1186 "1.1186") | Quenched and tempered steels | 0.37–0.44 | 16 | | [C40M2](/materials/iso/c40m2 "C40M2") | [1.1189](/materials/material-no/1.1189 "1.1189") | Quenched and tempered steels | 0.37–0.44 | 8 | | [C45](/materials/din-en/c45 "C45") | [1.0503](/materials/material-no/1.0503 "1.0503") | Quenched and tempered steels | 0.42–0.5 | 24 | | [C45 C45E4 C45M2](/materials/iso/c45-c45e4-c45m2 "C45 C45E4 C45M2") | — | — | — | 3 | | [C45E4](/materials/iso/c45e4 "C45E4") | [1.1191](/materials/material-no/1.1191 "1.1191") | Quenched and tempered steels | 0.42–0.5 | 21 | | [C45E4](/materials/iso/c45e4 "C45E4") | [1.1191](/materials/material-no/1.1191 "1.1191") | Others | 0.42–0.5 | 18 | | [C45M2](/materials/iso/c45m2 "C45M2") | [1.1201](/materials/material-no/1.1201 "1.1201") | Quenched and tempered steels | 0.42–0.5 | 11 | | [C50](/materials/din-en/c50 "C50") | [1.0540](/materials/material-no/1.0540 "1.0540") | Quenched and tempered steels | 0.47–0.55 | 13 | | [C50](/materials/din-en/c50 "C50") | [1.0535](/materials/material-no/1.0535 "1.0535") | Quenched and tempered steels | 0.52–0.6 | 21 | | [C50 C50E4 C50M2](/materials/iso/c50-c50e4-c50m2 "C50 C50E4 C50M2") | [1.0540](/materials/material-no/1.0540 "1.0540") | Quenched and tempered steels | 0.47–0.55 | 13 | | [C50 C50E4 C50M2](/materials/iso/c50-c50e4-c50m2 "C50 C50E4 C50M2") | [1.1171](/materials/material-no/1.1171 "1.1171") | Others | 0.48–0.52 | 6 | | [C50 C50E4 C50M2](/materials/iso/c50-c50e4-c50m2 "C50 C50E4 C50M2") | [1.1201](/materials/material-no/1.1201 "1.1201") | Quenched and tempered steels | 0.42–0.5 | 11 | | [C50 C50E4 C50M2](/materials/iso/c50-c50e4-c50m2 "C50 C50E4 C50M2") | [1.1206](/materials/material-no/1.1206 "1.1206") | Quenched and tempered steels | 0.47–0.55 | 17 | | [C50 C50E4 C50M2](/materials/iso/c50-c50e4-c50m2 "C50 C50E4 C50M2") | [1.9505](/materials/material-no/1.9505 "1.9505") | Others | 0.46–0.53 | 6 | | [C50 C50E4 C50M2](/materials/iso/c50-c50e4-c50m2 "C50 C50E4 C50M2") | [1.0586](/materials/material-no/1.0586 "1.0586") | Steels for surface hardening | 0.48–0.53 | 7 | | [C50 C50E4 C50M2](/materials/iso/c50-c50e4-c50m2 "C50 C50E4 C50M2") | [1.1213](/materials/material-no/1.1213 "1.1213") | Steels for surface hardening | 0.5–0.57 | 11 | | [C50 C50E4 C50M2](/materials/iso/c50-c50e4-c50m2 "C50 C50E4 C50M2") | [1.1241](/materials/material-no/1.1241 "1.1241") | Steels for surface hardening | 0.47–0.55 | 8 | | [C50 C50E4 C50M2](/materials/iso/c50-c50e4-c50m2 "C50 C50E4 C50M2") | [1.9505](/materials/material-no/1.9505 "1.9505") | Steels for surface hardening | 0.48–0.55 | 6 | | [C50E4](/materials/iso/c50e4 "C50E4") | [1.0540](/materials/material-no/1.0540 "1.0540") | Quenched and tempered steels | 0.47–0.55 | 13 | | [C50E4](/materials/iso/c50e4 "C50E4") | [1.1206](/materials/material-no/1.1206 "1.1206") | Quenched and tempered steels | 0.47–0.55 | 17 | | [C50M2](/materials/iso/c50m2 "C50M2") | [1.1241](/materials/material-no/1.1241 "1.1241") | Steels for surface hardening | 0.47–0.55 | 8 | | [C55](/materials/din-en/c55 "C55") | [1.0535](/materials/material-no/1.0535 "1.0535") | Quenched and tempered steels | 0.52–0.6 | 21 | | [C55E4](/materials/iso/c55e4 "C55E4") | [1.1203](/materials/material-no/1.1203 "1.1203") | Quenched and tempered steels | 0.52–0.6 | 15 | | [C55E4](/materials/iso/c55e4 "C55E4") | [1.0535](/materials/material-no/1.0535 "1.0535") | Quenched and tempered steels | 0.52–0.6 | 21 | | [C55M2](/materials/iso/c55m2 "C55M2") | [1.1209](/materials/material-no/1.1209 "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. [Previous](/materials/iso/page/4 "Previous") Page 5 of 11[Next](/materials/iso/page/6 "Next")