--- title: "C70U — Unalloyed tool steels / carbon steels" description: "C70U: 21 equivalent designations across 12 standards, with the recorded chemical composition shown next to the source text." canonical: https://steelequivalents.com/materials/din-en/c70u language: en robots: index, follow og_type: website type: material-detail language_alternates: en: https://steelequivalents.com/materials/din-en/c70u.md cs: https://steelequivalents.com/cs/materiály/din-en/c70u.md de: https://steelequivalents.com/de/werkstoffe/din-en/c70u.md es: https://steelequivalents.com/es/materiales/din-en/c70u.md fr: https://steelequivalents.com/fr/matériaux/din-en/c70u.md hu: https://steelequivalents.com/hu/anyagok/din-en/c70u.md it: https://steelequivalents.com/it/materiali/din-en/c70u.md nl: https://steelequivalents.com/nl/materialen/din-en/c70u.md pl: https://steelequivalents.com/pl/materiały/din-en/c70u.md pt: https://steelequivalents.com/pt/materiais/din-en/c70u.md ru: https://steelequivalents.com/ru/материалы/din-en/c70u.md tr: https://steelequivalents.com/tr/malzemeler/din-en/c70u.md zh: https://steelequivalents.com/zh/材料/din-en/c70u.md ja: https://steelequivalents.com/ja/材料/din-en/c70u.md ar: https://steelequivalents.com/ar/المواد/din-en/c70u.md ko: https://steelequivalents.com/ko/재료/din-en/c70u.md pt-br: https://steelequivalents.com/pt-br/materiais/din-en/c70u.md hi: https://steelequivalents.com/hi/सामग्री/din-en/c70u.md content_hash: sha256:47cb6dd6a223288d2faf783fb7c0bcb651b705f23e75c4fa00950d500b95a949 generated: 2026-09-22 --- > **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/din-en/c70u > Canonical URL: https://steelequivalents.com/materials/din-en/c70u > 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. DIN / EN · Europe · 21 designations # C70U C70U is a material in the category Unalloyed tool steels / carbon steels, held under material number 1.1520. We list 20 designations recorded for this grade, in the standards DIN / EN, AISI / SAE, AFNOR, ISO, JIS, GB, GOST, UNI, ČSN, PN, STN and ÖNORM. Its recorded composition includes C 0.65–0.75%, Si 0.1–0.3%, P 0.03%, S 0.03% and Mn 0.1–0.4%. Recorded mechanical properties include Rm 650 N/mm², A5 15% and HB 183–187; these figures vary with the delivery condition and dimension. Its recorded density is 7.83–7.85 g/cm³. Further recorded physical values: λ 29–46 W/(m·K), cp 580–970 J/(kg·K) and ρ el. 130 nΩ·m; several of these are temperature-dependent. Recorded transformation points: Ac1 730 °C, Ac3 770 °C and Ar1 700 °C. It is recorded as not intended for welding. - [*Material no.* **1.1520**](/materials/material-no/1.1520 "Material no.: 1.1520") - [*Category* **Unalloyed tool steels / carbon steels · 35 grades**](/categories/unalloyed-tool-steels-carbon-steels "Category: Unalloyed tool steels / carbon steels · 35 grades") - *Designations* **21** [Search](/search "Steel grade search")[Inquiry](/inquiry?material=3561be6c-1e28-4aa0-918b-ae58c82fbffb&designation=73173fb7-d780-4311-881b-ccb1acd3190d "Inquiry")[**Datasheet as PDF** Print-ready A4 document **Generating …** **Download started** **Try again**](/materials/din-en/c70u.pdf "Datasheet as PDF") ## About Unalloyed tool steels / carbon steels Unalloyed tool steels are carbon steels whose working properties are developed primarily through carbon content and heat treatment. They are characterised by high attainable hardness and wear resistance, and are used for cutting tools, punches, dies, gauges and other tooling where edge retention and resistance to deformation are important. This describes the material class as a whole. Always confirm the individual grade against the standard before ordering. ## Also known as 21 designations · 12 standards · nothing hidden 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. DIN / EN Europe · 4 - [1.1620 Indicative](/materials/material-no/1.1620 "DIN / EN 1.1620") - **C70U This grade’s own name** - [C70W1 This grade’s own name Withdrawn](/materials/din-en/c70w1 "DIN / EN C70W1") - [C70W2 Indicative](/materials/din-en/c70w2 "DIN / EN C70W2") AISI / SAE United States · 1 - [W1-7 Indicative](/materials/aisi-sae/w1-7 "AISI / SAE W1-7") AFNOR France · 1 - [C70E2U Indicative](/materials/afnor/c70e2u "AFNOR C70E2U") ISO International · 2 - **C70U Indicative** - [C70W1 Indicative](/materials/din-en/c70w1 "ISO C70W1") JIS Japan · 2 - [SK6 Indicative](/materials/jis/sk6 "JIS SK6") - [SK7 Indicative](/materials/jis/sk7 "JIS SK7") GB China · 1 - [T7 Indicative](/materials/gb/t7 "GB T7") GOST Russia / CIS · 2 - [U7 Indicative](/materials/bds/u7 "GOST U7") - [У7А Indicative](/materials/gost/u7a "GOST У7А") UNI Italy · 1 - [C70KU Indicative](/materials/uni/c70ku "UNI C70KU") ČSN Czechia · 2 - [19132 Indicative](/materials/csn/19132 "ČSN 19132") - [19133 Indicative](/materials/csn/19133 "ČSN 19133") STN Slovakia · 2 - [19 132 Indicative](/materials/csn/19132 "STN 19 132") - [19 133 Indicative](/materials/csn/19133 "STN 19 133") PN Poland · 2 - [N7 Indicative](/materials/pn/n7 "PN N7") - [N7E Indicative](/materials/pn/n7e "PN N7E") ÖNORM Austria · 1 - [K970 Indicative](/materials/onorm/k970 "ÖNORM K970") Every designation on file is listed — no truncation, no “+ n more”. Each one is itself a route that leads back here. ## Chemical composition 5 elements on file · weight % What this alloy is Fe C Mn Si Iron — the balance, never listed by a standard — 98.8 % C — 0.7 % Mn — 0.3 % Si — 0.2 % Traces & impurities · 0.1 % Logarithmic scale, 0.01 % to 100 % — every value here compares directly, decade by decade. | Element | % by weight | |---|---| | C | 0.65–0.75 | | Si | 0.1–0.3 | | Mn | 0.1–0.4 | | P | 0.03 | | S | 0.03 | Carbon Silicon Manganese Phosphorus Sulfur 0.01 % 0.1 % 1 % 10 % 100 % The scale is logarithmic, not the element’s raw share of the alloy — the only honest way to fit 0.01 % and 100 % in one picture, and it means every value here can be compared with every other. | Element | As published source text, verbatim | Min% by weight | Max% by weight | Bound | |---|---|---|---|---| | C | 0,65-0,75 | 0.650 | 0.750 | Range | | Si | 0,10-0,30 | 0.100 | 0.300 | Range | | P | 0,03 | 0.030 | 0.030 | Exact | | S | 0,03 | 0.030 | 0.030 | Exact | | Mn | 0,10-0,40 | 0.100 | 0.400 | Range | The published column is the source string byte-for-byte, decimal comma and all; Min and Max are the parsed bounds. Elements not listed have no value on file — they are omitted, never inferred. ## Predicted transformation temperatures Not enough recorded composition to predict a transformation temperature for this grade — missing: Ni, Cr, Mo. ## Physical & mechanical properties Density 7,85 g/cm³ Exact Transformation point Ac1 730 °C Exact Transformation point Ac3 770 °C Exact · Ac3(Acm) Transformation point Ar1 700 °C Exact Weldability not suitable for welding As published: is not used. Flake sensitivity not susceptible As published: not predisposed Temper brittleness not susceptible As published: not predisposed An absent property means we hold no value for it — it is left out rather than estimated, interpolated from a neighbouring grade, or filled from a handbook. It does not mean the property is undefined for the material. ## Properties by condition 4 conditions · 18 values By delivery state**Soft annealed** source `steelnumber` | Delivery state | HB | |---|---| | Soft annealed | 183 | By dimension**As-delivered state** source `splav` | Dimension mm | Rm N/mm² | A5% | |---|---|---| | to 1 | 650 | 15 | By delivery state**no delivery state stated** source `splav` | Delivery state | HB | |---|---| | (annealing) , GOST 1435-99 | 187 | At temperature**no delivery state stated** source `splav` | Temperature °C | Density g/cm³ | Thermal conductivity W/(m·K) | Specific heat capacity J/(kg·K) | Electrical resistivity nΩ·m | |---|---|---|---|---| | 20 | 7.83 | 46 | — | 130 | | 100 | — | 46 | — | — | | 300 | — | 41 | 580 | — | | 400 | — | — | 664 | — | | 500 | — | — | 819 | — | | 600 | — | 33 | 970 | — | | 700 | — | — | 710 | — | | 800 | — | — | 706 | — | | 900 | — | 29 | 685 | — | Every figure holds only for the condition on its own row. Values are never merged across conditions or across sources, never averaged, and never interpolated between two rows. An em dash means no value on file — never zero. Figures are converted to the unit in the column header; the source’s own wording is kept and shown where the two differ. ## Similar grades — and why Selection rule, stated so you can disagree with it: same number class 1.1, a shared category, and a published range for Mn / Si that overlaps this grade’s. These are neighbours in composition space — they are not equivalents, and none is claimed to be interchangeable with this grade. [C80U 1.1525 Mn 0,10-0,40 · Si 0,10-0,30 - ΔMn 0.00 - ΔSi 0.00 - 44 designations](/materials/din-en/c80u "C80U")[C105W2 1.1535 Mn 0,10-0,40 · Si 0,10-0,30 - ΔMn 0.00 - ΔSi 0.00 - 26 designations](/materials/din-en/c105w2 "C105W2")[1.1545 1.1545 Mn 0,10-0,40 · Si 0,10-0,30 - ΔMn 0.00 - ΔSi 0.00 - 67 designations](/materials/material-no/1.1545 "1.1545")[C110W1 1.1555 Mn 0,10-0,40 · Si 0,10-0,30 - ΔMn 0.00 - ΔSi 0.00 - 31 designations](/materials/din-en/c110w1 "C110W1")[C110U 1.1554 Mn 0,10-0,35 · Si 0,10-0,30 - ΔMn 0.03 - ΔSi 0.00 - 9 designations](/materials/din-en/c110u "C110U")[C125U 1.1563 Mn 0,10-0,35 · Si 0,10-0,30 - ΔMn 0.03 - ΔSi 0.00 - 32 designations](/materials/din-en/c125u "C125U") ## Looking for this grade under another name? Search the catalogue by designation, material number or composition — every name on this page is itself a way in. [Search](/search "Steel grade search")[Inquiry](/inquiry?material=3561be6c-1e28-4aa0-918b-ae58c82fbffb&designation=73173fb7-d780-4311-881b-ccb1acd3190d "Inquiry")[**Datasheet as PDF** Print-ready A4 document **Generating …** **Download started** **Try again**](/materials/din-en/c70u.pdf "Datasheet as PDF")