--- title: "4120 — composition, equivalents and standards" description: "4120: 4 equivalent designations across 4 standards, with the recorded chemical composition shown next to the source text." canonical: https://steelequivalents.com/materials/astm/4120 language: en robots: index, follow og_type: website type: material-detail language_alternates: en: https://steelequivalents.com/materials/astm/4120.md cs: https://steelequivalents.com/cs/materiály/astm/4120.md de: https://steelequivalents.com/de/werkstoffe/astm/4120.md es: https://steelequivalents.com/es/materiales/astm/4120.md fr: https://steelequivalents.com/fr/matériaux/astm/4120.md hu: https://steelequivalents.com/hu/anyagok/astm/4120.md it: https://steelequivalents.com/it/materiali/astm/4120.md nl: https://steelequivalents.com/nl/materialen/astm/4120.md pl: https://steelequivalents.com/pl/materiały/astm/4120.md pt: https://steelequivalents.com/pt/materiais/astm/4120.md ru: https://steelequivalents.com/ru/материалы/astm/4120.md tr: https://steelequivalents.com/tr/malzemeler/astm/4120.md zh: https://steelequivalents.com/zh/材料/astm/4120.md ja: https://steelequivalents.com/ja/材料/astm/4120.md ar: https://steelequivalents.com/ar/المواد/astm/4120.md ko: https://steelequivalents.com/ko/재료/astm/4120.md pt-br: https://steelequivalents.com/pt-br/materiais/astm/4120.md hi: https://steelequivalents.com/hi/सामग्री/astm/4120.md content_hash: sha256:be3c5c8e9c1d68ee1fc5b6a76f6bde7d69affa494d77a36c9f33a448d48978b5 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/astm/4120 > Canonical URL: https://steelequivalents.com/materials/astm/4120 > 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. ASTM · United States · 4 designations # 4120 ML20CrMo is a grade designated under GB. Its recorded composition includes C 0.18–0.23%, Si 0.1–0.3%, Cr 0.9–1.2%, Mn 0.6–0.9% and Mo 0.15–0.3%. We list 3 designations recorded for this grade, in the standards ASTM, ISO and JIS. Recorded mechanical properties include Rm ≤ 560 N/mm². - *Designations* **4** [Search](/search "Steel grade search")[Inquiry](/inquiry?material=e72caf8d-ab79-44b1-b6fd-85e5bb2e5173&designation=fe6dbd4c-544e-4542-aeb2-afd5b199c50d "Inquiry")[**Datasheet as PDF** Print-ready A4 document **Generating …** **Download started** **Try again**](/materials/astm/4120.pdf "Datasheet as PDF") ## If you came for one of these The most-used names for this grade. - [GB ML20CrMo This grade’s own name](/materials/gb/ml20crmo "GB ML20CrMo") ## 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. ASTM United States · 1 - **4120 Indicative** ISO International · 1 - [20CrMo4 Indicative](/materials/din-en/20crmo4 "ISO 20CrMo4") JIS Japan · 1 - [SCM420 Indicative](/materials/ks/scm420 "JIS SCM420") GB China · 1 - [ML20CrMo This grade’s own name](/materials/gb/ml20crmo "GB ML20CrMo") Every designation on file is listed — no truncation, no “+ n more”. Each one is itself a route that leads back here. ## Chemical composition 7 elements on file · weight % What this alloy is Fe Cr Mn Mo Iron — the balance, never listed by a standard — 97.5 % Cr — 1.1 % Mn — 0.8 % Mo — 0.2 % Traces & impurities · 0.5 % Logarithmic scale, 0.01 % to 100 % — every value here compares directly, decade by decade. | Element | % by weight | |---|---| | C | 0.18–0.23 | | Si | 0.1–0.3 | | Mn | 0.6–0.9 | | P | ≤ 0.025 | | S | ≤ 0.025 | | Cr | 0.9–1.2 | | Mo | 0.15–0.3 | Carbon Silicon Manganese Phosphorus Sulfur Chromium Molybdenum 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 | 0.18-0.23 | 0.180 | 0.230 | Range | | Si | 0.1-0.3 | 0.100 | 0.300 | Range | | P | ≤0.025 | — | 0.025 | Max | | S | ≤0.025 | — | 0.025 | Max | | Cr | 0.9-1.2 | 0.900 | 1.200 | Range | | Mn | 0.6-0.9 | 0.600 | 0.900 | Range | | Mo | 0.15-0.3 | 0.150 | 0.300 | 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. ## Physical & mechanical properties Rm ≤560 N/mm² Max 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. ## 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=e72caf8d-ab79-44b1-b6fd-85e5bb2e5173&designation=fe6dbd4c-544e-4542-aeb2-afd5b199c50d "Inquiry")[**Datasheet as PDF** Print-ready A4 document **Generating …** **Download started** **Try again**](/materials/astm/4120.pdf "Datasheet as PDF")