--- title: "45MnB — composition, equivalents and standards" description: "45MnB is a designation in GB for the grade also listed as 50B44. We list 2 designations recorded for this grade, in the standards ASTM and GB." canonical: https://steelequivalents.com/materials/gb/45mnb language: en robots: index, follow og_type: website type: material-detail language_alternates: en: https://steelequivalents.com/materials/gb/45mnb.md cs: https://steelequivalents.com/cs/materiály/gb/45mnb.md de: https://steelequivalents.com/de/werkstoffe/gb/45mnb.md es: https://steelequivalents.com/es/materiales/gb/45mnb.md fr: https://steelequivalents.com/fr/matériaux/gb/45mnb.md hu: https://steelequivalents.com/hu/anyagok/gb/45mnb.md it: https://steelequivalents.com/it/materiali/gb/45mnb.md nl: https://steelequivalents.com/nl/materialen/gb/45mnb.md pl: https://steelequivalents.com/pl/materiały/gb/45mnb.md pt: https://steelequivalents.com/pt/materiais/gb/45mnb.md ru: https://steelequivalents.com/ru/материалы/gb/45mnb.md tr: https://steelequivalents.com/tr/malzemeler/gb/45mnb.md zh: https://steelequivalents.com/zh/材料/gb/45mnb.md ja: https://steelequivalents.com/ja/材料/gb/45mnb.md ar: https://steelequivalents.com/ar/المواد/gb/45mnb.md ko: https://steelequivalents.com/ko/재료/gb/45mnb.md pt-br: https://steelequivalents.com/pt-br/materiais/gb/45mnb.md hi: https://steelequivalents.com/hi/सामग्री/gb/45mnb.md content_hash: sha256:66aba9e88eadf69c104f7aac9652b4bda9cd3d91acf5e1441adf39583ff94e5a 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/45mnb > Canonical URL: https://steelequivalents.com/materials/gb/45mnb > 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 · 2 designations # 45MnB 45MnB is a designation in GB for the grade also listed as 50B44. We list 2 designations recorded for this grade, in the standards ASTM and GB. - *Designations* **2** [Search](/search "Steel grade search")[Inquiry](/inquiry?material=43f7350a-50bd-4a69-a7b8-3d43028863fe&designation=0c3cdf1f-5a66-44e2-b828-9774ebbdcade "Inquiry")[**Datasheet as PDF** Print-ready A4 document **Generating …** **Download started** **Try again**](/materials/gb/45mnb.pdf "Datasheet as PDF") ## Also known as 2 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. ASTM United States · 1 - [50B44 Indicative](/materials/astm/50b44 "ASTM 50B44") GB China · 1 - **45MnB 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. ## Predicted transformation temperatures Not enough recorded composition to predict a transformation temperature for this grade — missing: C, Mn, Si, Ni, Cr, Mo. ## 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 1 conditions · 4 values By dimension**no delivery state stated** source `caishuku` | Diameter mm | Rm N/mm² | Re N/mm² | A% | HB | |---|---|---|---|---| | 25 – 25 | ≥ 1030 | ≥ 835 | ≥ 9 | ≤ 217 | 1 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 - Quenching and Tempering 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/azhlNWIxMTk2OTU_ "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=43f7350a-50bd-4a69-a7b8-3d43028863fe&designation=0c3cdf1f-5a66-44e2-b828-9774ebbdcade "Inquiry")[**Datasheet as PDF** Print-ready A4 document **Generating …** **Download started** **Try again**](/materials/gb/45mnb.pdf "Datasheet as PDF")