--- title: "ML42CrMo — composition, equivalents and standards" description: "ML42CrMo is a designation in GB for the grade also listed as 42CrMo4. Designations recorded for this grade: 5." canonical: https://steelequivalents.com/materials/gb/ml42crmo language: en robots: index, follow og_type: website type: material-detail language_alternates: en: https://steelequivalents.com/materials/gb/ml42crmo.md cs: https://steelequivalents.com/cs/materiály/gb/ml42crmo.md de: https://steelequivalents.com/de/werkstoffe/gb/ml42crmo.md es: https://steelequivalents.com/es/materiales/gb/ml42crmo.md fr: https://steelequivalents.com/fr/matériaux/gb/ml42crmo.md hu: https://steelequivalents.com/hu/anyagok/gb/ml42crmo.md it: https://steelequivalents.com/it/materiali/gb/ml42crmo.md nl: https://steelequivalents.com/nl/materialen/gb/ml42crmo.md pl: https://steelequivalents.com/pl/materiały/gb/ml42crmo.md pt: https://steelequivalents.com/pt/materiais/gb/ml42crmo.md ru: https://steelequivalents.com/ru/материалы/gb/ml42crmo.md tr: https://steelequivalents.com/tr/malzemeler/gb/ml42crmo.md zh: https://steelequivalents.com/zh/材料/gb/ml42crmo.md ja: https://steelequivalents.com/ja/材料/gb/ml42crmo.md ar: https://steelequivalents.com/ar/المواد/gb/ml42crmo.md ko: https://steelequivalents.com/ko/재료/gb/ml42crmo.md pt-br: https://steelequivalents.com/pt-br/materiais/gb/ml42crmo.md hi: https://steelequivalents.com/hi/सामग्री/gb/ml42crmo.md content_hash: sha256:d7c8361a442c8866c9e9054d3604dedd394f693a3056d86861ec076a55b29757 generated: 2026-09-24 --- > **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/ml42crmo > Canonical URL: https://steelequivalents.com/materials/gb/ml42crmo > 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 · 5 designations # ML42CrMo ML42CrMo is a designation in GB for the grade also listed as 42CrMo4. We list 5 designations recorded for this grade, in the standards DIN / EN, AISI / SAE, ISO, JIS and GB. - *Designations* **5** [Search](/search "Steel grade search")[Inquiry](/inquiry?material=f7a00035-175b-4df8-8789-4c2cc2bb1479&designation=44af56b9-ea44-4127-8840-7cbfa42668ee "Inquiry")[**Datasheet as PDF** Print-ready A4 document **Generating …** **Download started** **Try again**](/materials/gb/ml42crmo.pdf "Datasheet as PDF") ## Also known as 5 designations · 5 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 - [42CrMo4 Indicative](/materials/din-en/42crmo4 "DIN / EN 42CrMo4") AISI / SAE United States · 1 - [4140 Indicative](/materials/aisi-sae/4140 "AISI / SAE 4140") ISO International · 1 - [42CrMo4E Indicative](/materials/iso/42crmo4e "ISO 42CrMo4E") JIS Japan · 1 - [SCM440 Indicative](/materials/jis/scm440 "JIS SCM440") GB China · 1 - **ML42CrMo 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 9 elements on file · weight % What this alloy is Fe Cr Mn C Iron — the balance, never listed by a standard — 96.8 % Cr — 1.1 % Mn — 0.8 % C — 0.4 % Traces & impurities · 1 % Logarithmic scale, 0.01 % to 100 % — every value here compares directly, decade by decade. | Element | % by weight | |---|---| | C | 0.38–0.45 | | Si | ≤ 0.3 | | Mn | 0.6–0.9 | | P | ≤ 0.035 | | S | ≤ 0.035 | | Cr | 0.9–1.2 | | Mo | 0.15–0.25 | | Ni | ≤ 0.2 | | Cu | ≤ 0.2 | Carbon Silicon Manganese Phosphorus Sulfur Chromium Molybdenum 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 | 0.38-0.45 | 0.380 | 0.450 | Range | | Si | ≤0.3 | — | 0.300 | Max | | P | ≤0.035 | — | 0.035 | Max | | S | ≤0.035 | — | 0.035 | Max | | Cr | 0.9-1.2 | 0.900 | 1.200 | Range | | Mn | 0.6-0.9 | 0.600 | 0.900 | Range | | Ni | ≤0.2 | — | 0.200 | Max | | Cu | ≤0.2 | — | 0.200 | Max | | Mo | 0.15-0.25 | 0.150 | 0.250 | 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 769 °C Predicted Ae1 742 °C Predicted Acm 645 °C Predicted Bs 525 °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 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 0 conditions · 0 values 3 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. ## Heat treatment **GB T 6478-2001** In this order 1. Quenching 830–870 °C Cooling Oil 2. Tempering 500–600 °C Source: [www.caishuku.com](https://www.caishuku.com/detail/azhlNWIxMzQz "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=f7a00035-175b-4df8-8789-4c2cc2bb1479&designation=44af56b9-ea44-4127-8840-7cbfa42668ee "Inquiry")[**Datasheet as PDF** Print-ready A4 document **Generating …** **Download started** **Try again**](/materials/gb/ml42crmo.pdf "Datasheet as PDF")