--- title: "20Mn — composition, equivalents and standards" description: "20Mn is a designation in GB for the grade also listed as P245GH. Designations recorded for this grade: 4." canonical: https://steelequivalents.com/materials/gb/20mn language: en robots: index, follow og_type: website type: material-detail language_alternates: en: https://steelequivalents.com/materials/gb/20mn.md cs: https://steelequivalents.com/cs/materiály/gb/20mn.md de: https://steelequivalents.com/de/werkstoffe/gb/20mn.md es: https://steelequivalents.com/es/materiales/gb/20mn.md fr: https://steelequivalents.com/fr/matériaux/gb/20mn.md hu: https://steelequivalents.com/hu/anyagok/gb/20mn.md it: https://steelequivalents.com/it/materiali/gb/20mn.md nl: https://steelequivalents.com/nl/materialen/gb/20mn.md pl: https://steelequivalents.com/pl/materiały/gb/20mn.md pt: https://steelequivalents.com/pt/materiais/gb/20mn.md ru: https://steelequivalents.com/ru/материалы/gb/20mn.md tr: https://steelequivalents.com/tr/malzemeler/gb/20mn.md zh: https://steelequivalents.com/zh/材料/gb/20mn.md ja: https://steelequivalents.com/ja/材料/gb/20mn.md ar: https://steelequivalents.com/ar/المواد/gb/20mn.md ko: https://steelequivalents.com/ko/재료/gb/20mn.md pt-br: https://steelequivalents.com/pt-br/materiais/gb/20mn.md hi: https://steelequivalents.com/hi/सामग्री/gb/20mn.md content_hash: sha256:14f2e4574933004ce7811d7d7b03c75b0a42e47000eeee927424767ab10f4b9a generated: 2026-09-23 --- > **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/gb/20mn > Canonical URL: https://steelequivalents.com/materials/gb/20mn > 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. GB · China · 4 designations # 20Mn 20Mn is a designation in GB for the grade also listed as P245GH. We list 4 designations recorded for this grade, in the standards DIN / EN, ASTM, AFNOR and GB. - *Designations* **4** [Search](/search "Steel grade search")[Inquiry](/inquiry?material=49a992a5-c6fc-4709-8304-922b72c32607&designation=341896e1-fe6f-46d2-9859-bd33d688afad "Inquiry")[**Datasheet as PDF** Print-ready A4 document **Generating …** **Download started** **Try again**](/materials/gb/20mn.pdf "Datasheet as PDF") ## Also known as 4 designations · 4 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 · 1 - [P245GH Indicative](/materials/din-en/p245gh "DIN / EN P245GH") ASTM United States · 1 - [A105 Indicative](/materials/din-en/a105 "ASTM A105") AFNOR France · 1 - [A42AP Indicative](/materials/afnor/a42ap "AFNOR A42AP") GB China · 1 - **20Mn This grade’s own name** Every designation on file is listed — no truncation, no “+ n more”. Each one is itself a route that leads back here. ## Chemical composition 8 elements on file · weight % What this alloy is Fe Mn Ni Si Iron — the balance, never listed by a standard — 97.9 % Mn — 0.9 % Ni — 0.3 % Si — 0.3 % Traces & impurities · 0.7 % Logarithmic scale, 0.01 % to 100 % — every value here compares directly, decade by decade. | Element | % by weight | |---|---| | C | 0.17–0.23 | | Si | 0.17–0.37 | | Mn | 0.7–1 | | P | ≤ 0.035 | | S | ≤ 0.03 | | Cr | ≤ 0.2 | | Ni | ≤ 0.3 | | Cu | ≤ 0.25 | Carbon Silicon Manganese Phosphorus Sulfur Chromium Nickel Copper 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 | 0.17-0.23 | 0.170 | 0.230 | Range | | Si | 0.17-0.37 | 0.170 | 0.370 | Range | | P | ≤0.035 | — | 0.035 | Max | | S | ≤0.03 | — | 0.030 | Max | | Cr | ≤0.2 | — | 0.200 | Max | | Mn | 0.7-1 | 0.700 | 1.000 | Range | | Ni | ≤0.3 | — | 0.300 | Max | | Cu | ≤0.25 | — | 0.250 | Max | 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: Mo. ## Physical & mechanical properties Rm ≥450 N/mm² Min A ≥24% Min 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 1 conditions · 11 values At temperature**no delivery state stated** source `caishuku` | Temperature °C | Elastic modulus GPa | Thermal expansion coefficient 10^-6/K | Thermal conductivity W/(m·K) | Specific heat capacity J/(kg·K) | |---|---|---|---|---| | 20 | 210 | — | 53.59 | 469 | | 100 | — | 12.3 | 51.08 | — | | 200 | — | — | 43.96 | — | | 300 | 185 | 13.2 | — | — | | 400 | 175 | — | — | — | | 500 | — | — | 34.75 | — | | 600 | — | 14.9 | — | — | 2 further values are held for this grade under a condition the source did not name — a bound with no quantity attached. They are withheld rather than shown against a guessed condition. 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. ## Heat treatment Supply condition - Annealing and Tempering and Normalizing Supply condition - Normalizing Test specimen size d=25 Conditions the standard permits on delivery. No temperature or medium is published for these, so no order and no alternation is implied. Source: [www.caishuku.com](https://www.caishuku.com/detail/azhlNWIxMzM2OA__ "Source: www.caishuku.com") ## 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=49a992a5-c6fc-4709-8304-922b72c32607&designation=341896e1-fe6f-46d2-9859-bd33d688afad "Inquiry")[**Datasheet as PDF** Print-ready A4 document **Generating …** **Download started** **Try again**](/materials/gb/20mn.pdf "Datasheet as PDF")