--- title: "18MnMo4-5 — Heat-resistant structural steels" description: "18MnMo4-5: 4 equivalent designations across 2 standards, with the recorded chemical composition shown next to the source text." canonical: https://steelequivalents.com/materials/din-en/18mnmo4-5 language: en robots: index, follow og_type: website type: material-detail language_alternates: en: https://steelequivalents.com/materials/din-en/18mnmo4-5.md cs: https://steelequivalents.com/cs/materiály/din-en/18mnmo4-5.md de: https://steelequivalents.com/de/werkstoffe/din-en/18mnmo4-5.md es: https://steelequivalents.com/es/materiales/din-en/18mnmo4-5.md fr: https://steelequivalents.com/fr/matériaux/din-en/18mnmo4-5.md hu: https://steelequivalents.com/hu/anyagok/din-en/18mnmo4-5.md it: https://steelequivalents.com/it/materiali/din-en/18mnmo4-5.md nl: https://steelequivalents.com/nl/materialen/din-en/18mnmo4-5.md pl: https://steelequivalents.com/pl/materiały/din-en/18mnmo4-5.md pt: https://steelequivalents.com/pt/materiais/din-en/18mnmo4-5.md ru: https://steelequivalents.com/ru/материалы/din-en/18mnmo4-5.md tr: https://steelequivalents.com/tr/malzemeler/din-en/18mnmo4-5.md zh: https://steelequivalents.com/zh/材料/din-en/18mnmo4-5.md ja: https://steelequivalents.com/ja/材料/din-en/18mnmo4-5.md ar: https://steelequivalents.com/ar/المواد/din-en/18mnmo4-5.md ko: https://steelequivalents.com/ko/재료/din-en/18mnmo4-5.md pt-br: https://steelequivalents.com/pt-br/materiais/din-en/18mnmo4-5.md hi: https://steelequivalents.com/hi/सामग्री/din-en/18mnmo4-5.md content_hash: sha256:73599e36a9c346f6409a3135365a98ddaaaf049d5a5ef0f42ca9ed03dff3f564 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/18mnmo4-5 > Canonical URL: https://steelequivalents.com/materials/din-en/18mnmo4-5 > 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. DIN / EN · Europe · 4 designations # 18MnMo4-5 18MnMo4-5 is a material in the category [Heat-resistant structural steels](/categories/heat-resistant-structural-steels "Heat-resistant structural steels"), held under material number 1.5414. Its recorded composition includes C ≤ 0.2%, Si ≤ 0.4%, Cr ≤ 0.3%, Mn 0.9–1.5% and Mo 0.45–0.6%. We list 3 designations recorded for this grade, in the standards UNS. Recorded mechanical properties include Rm 480–650 N/mm² and ReH 310–345 N/mm²; these figures vary with the delivery condition and dimension. Its recorded density is 7.85 g/cm³. - [*Material no.* **1.5414**](/materials/material-no/1.5414 "Material no.: 1.5414") - [*Category* **Heat-resistant structural steels · 62 grades**](/categories/heat-resistant-structural-steels "Category: Heat-resistant structural steels · 62 grades") - *Designations* **4** [Search](/search "Steel grade search")[Inquiry](/inquiry?material=5e72e31b-a58e-4f73-8cad-9493ea9972a2&designation=ab005a3e-c2c5-448a-bdf3-15226a8764a2 "Inquiry")[**Datasheet as PDF** Print-ready A4 document **Generating …** **Download started** **Try again**](/materials/din-en/18mnmo4-5.pdf "Datasheet as PDF") ## If you came for one of these The most-used names for this grade. - [UNS K12021 This grade’s own name · 3 grades on that route](/materials/uns/k12021 "UNS K12021") ## About Heat-resistant structural steels Heat-resistant structural steels are structural steels designed to retain useful strength and dimensional stability at elevated temperatures. They are used for load-bearing components in hot-service equipment where mechanical performance must be maintained during heating. This describes the material class as a whole. Always confirm the individual grade against the standard before ordering. ## Also known as 4 designations · 2 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 - **18MnMo4-5 This grade’s own name** UNS United States · 3 - [K12021 This grade’s own name](/materials/uns/k12021 "UNS K12021") - [K12022 Indicative](/materials/uns/k12022 "UNS K12022") - [K12039 Indicative](/materials/uns/k12039 "UNS K12039") Every designation on file is listed — no truncation, no “+ n more”. Each one is itself a route that leads back here. ## Chemical composition 10 elements on file · weight % What this alloy is Fe Mn Mo Si Iron — the balance, never listed by a standard — 96.7 % Mn — 1.2 % Mo — 0.5 % Si — 0.4 % Traces & impurities · 1.1 % Logarithmic scale, 0.01 % to 100 % — every value here compares directly, decade by decade. | Element | % by weight | |---|---| | C | ≤ 0.2 | | Si | ≤ 0.4 | | Mn | 0.9–1.5 | | P | 0.015 | | S | 0.005 | | Cr | ≤ 0.3 | | Mo | 0.45–0.6 | | Ni | 0.3 | | Cu | ≤ 0.3 | | N | 0.012 | Carbon Silicon Manganese Phosphorus Sulfur Chromium Molybdenum Nickel Copper Nitrogen 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 | ≤0,20 | — | 0.200 | Max | | N | 0,012 | 0.012 | 0.012 | Exact | | Si | ≤0,40 | — | 0.400 | Max | | P | 0,015 | 0.015 | 0.015 | Exact | | S | 0,005 | 0.005 | 0.005 | Exact | | Cr | ≤0,30 | — | 0.300 | Max | | Mn | 0,90-1,50 | 0.900 | 1.500 | Range | | Ni | 0,3 | 0.300 | 0.300 | Exact | | Cu | ≤0,30 | — | 0.300 | Max | | Mo | 0,45-0,60 | 0.450 | 0.600 | 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 computed from composition · °C Predicted Ae3 810 °C Predicted Ae1 714 °C Predicted Acm 440 °C Predicted Bs 534 °C These four temperatures are a CALCULATION from this grade's own composition, using the published Li, Niebuhr, Meekisho & Atteridge (1998) model — never a measurement, and computed from the UPPER BOUND of each element's specified range, not a mid-range figure. Where this grade also has a measured transformation point (Ac1, Ac3, Ar1, Ar3) on file, it is shown separately, in Physical & mechanical properties, and is never replaced by the predicted figures here — Ae (predicted, equilibrium) and Ac/Ar (measured, on heating or cooling) are different physical quantities and can differ by tens of degrees; a mismatch between the two is not an error in either. ## Physical & mechanical properties Density 7,85 g/cm³ Exact 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 · 5 values By thickness**no delivery state stated** source `steelnumber` | Thickness mm | ReH N/mm² | Rm N/mm² | |---|---|---| | ≤ 60 | 345 | — | | 60 – 150 | 325 | — | | ≤ 150 | — | 510 – 650 | | 150 – 250 | 310 | 480 – 620 | 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 1.5, a shared category, and a published range for Mn / Mo 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. [15MnMoV4-5 1.5402 Mn 0,90-1,40 · Mo 0,40-0,60 - ΔMn 0.05 - ΔMo 0.03 - 1 designations](/materials/din-en/15mnmov4-5 "15MnMoV4-5")[10MnMo4-5 1.5424 Mn 0,95-1,25 · Mo 0,48-0,62 - ΔMn 0.10 - ΔMo 0.03 - 1 designations](/materials/din-en/10mnmo4-5 "10MnMo4-5")[G18Mo5 1.5422 Mn 0,80-1,20 · Mo 0,45-0,65 - ΔMn 0.20 - ΔMo 0.03 - 1 designations](/materials/din-en/g18mo5 "G18Mo5")[11MnMo4-5 1.5425 Mn 0,85-1,15 · Mo 0,48-0,62 - ΔMn 0.20 - ΔMo 0.03 - 5 designations](/materials/din-en/11mnmo4-5 "11MnMo4-5")[13MnMo6-5 1.5426 Mn 1,35-1,65 · Mo 0,48-0,62 - ΔMn 0.30 - ΔMo 0.03 - 2 designations](/materials/din-en/13mnmo6-5 "13MnMo6-5")[26MnMoB6-4 1.5465 Mn 1,25-1,50 · Mo 0,30-0,45 - ΔMn 0.18 - ΔMo 0.15 - 1 designations](/materials/din-en/26mnmob6-4 "26MnMoB6-4") ## 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=5e72e31b-a58e-4f73-8cad-9493ea9972a2&designation=ab005a3e-c2c5-448a-bdf3-15226a8764a2 "Inquiry")[**Datasheet as PDF** Print-ready A4 document **Generating …** **Download started** **Try again**](/materials/din-en/18mnmo4-5.pdf "Datasheet as PDF")