--- title: "~BCMo 1 — Case hardening steels" description: "~BCMo 1 in MSZ: material number 1.7243, also listed as 18CrMo4. Category: Case hardening steels. Designations recorded for this grade: 23." canonical: https://steelequivalents.com/materials/msz/bcmo-1 language: en robots: index, follow og_type: website type: material-detail language_alternates: en: https://steelequivalents.com/materials/msz/bcmo-1.md cs: https://steelequivalents.com/cs/materiály/msz/bcmo-1.md de: https://steelequivalents.com/de/werkstoffe/msz/bcmo-1.md es: https://steelequivalents.com/es/materiales/msz/bcmo-1.md fr: https://steelequivalents.com/fr/matériaux/msz/bcmo-1.md hu: https://steelequivalents.com/hu/anyagok/msz/bcmo-1.md it: https://steelequivalents.com/it/materiali/msz/bcmo-1.md nl: https://steelequivalents.com/nl/materialen/msz/bcmo-1.md pl: https://steelequivalents.com/pl/materiały/msz/bcmo-1.md pt: https://steelequivalents.com/pt/materiais/msz/bcmo-1.md ru: https://steelequivalents.com/ru/материалы/msz/bcmo-1.md tr: https://steelequivalents.com/tr/malzemeler/msz/bcmo-1.md zh: https://steelequivalents.com/zh/材料/msz/bcmo-1.md ja: https://steelequivalents.com/ja/材料/msz/bcmo-1.md ar: https://steelequivalents.com/ar/المواد/msz/bcmo-1.md ko: https://steelequivalents.com/ko/재료/msz/bcmo-1.md pt-br: https://steelequivalents.com/pt-br/materiais/msz/bcmo-1.md hi: https://steelequivalents.com/hi/सामग्री/msz/bcmo-1.md content_hash: sha256:fb4feef4cc7095380d1b967cbf5332e6e6cb29482ee37e4332156a7a0dafc16e 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/msz/bcmo-1 > Canonical URL: https://steelequivalents.com/materials/msz/bcmo-1 > 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. MSZ · Hungary · 23 designations # ~BCMo 1 ~BCMo 1 is a designation in MSZ for the material held under material number 1.7243, also listed as 18CrMo4. It is a material in the category Case hardening steels. We list 23 designations recorded for this grade, in the standards DIN / EN, BS, AFNOR, UNE, ISO, JIS, GOST, UNI, ČSN, STN, PN, MSZ and STAS. - [*Material no.* **1.7243**](/materials/material-no/1.7243 "Material no.: 1.7243") - [*Category* **Case hardening steels · 60 grades**](/categories/case-hardening-steels "Category: Case hardening steels · 60 grades") - *Designations* **23** [Search](/search "Steel grade search")[Inquiry](/inquiry?material=8860e2c5-ae93-48e4-a267-54b9cb1f7a8b&designation=e99a4381-b9bf-4319-b536-8970f3ecd18e "Inquiry")[**Datasheet as PDF** Print-ready A4 document **Generating …** **Download started** **Try again**](/materials/msz/bcmo-1.pdf "Datasheet as PDF") ## If you came for one of these The most-used names for this grade. - [DIN / EN 18CrMo4 This grade’s own name](/materials/din-en/18crmo4 "DIN / EN 18CrMo4") ## About Case hardening steels Case hardening steels are steels designed to develop a hard, wear-resistant surface while retaining a tough and ductile core. They are used for components such as gears, shafts and other machine parts exposed to contact wear and cyclic loading. This describes the material class as a whole. Always confirm the individual grade against the standard before ordering. ## Also known as 23 designations · 13 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 - [18CrMo4 This grade’s own name](/materials/din-en/18crmo4 "DIN / EN 18CrMo4") BS United Kingdom · 2 - [708H20 Indicative](/materials/bs/708h20 "BS 708H20") - [708M20 Indicative](/materials/bs/708m20 "BS 708M20") AFNOR France · 2 - [18CD4 Indicative](/materials/afnor/18cd4 "AFNOR 18CD4") - [18CrMo4 Indicative](/materials/din-en/18crmo4 "AFNOR 18CrMo4") UNE Spain · 4 - [18CrMo4 Indicative](/materials/din-en/18crmo4 "UNE 18CrMo4") - [A-1550 Indicative](/materials/une/a-1550 "UNE A-1550") - [CMO Indicative](/materials/une/cmo "UNE CMO") - [F-1550 Indicative](/materials/une/f-1550 "UNE F-1550") ISO International · 3 - [15CrMo4 Indicative](/materials/din-en/15crmo4 "ISO 15CrMo4") - [18CrMo4 Indicative](/materials/din-en/18crmo4 "ISO 18CrMo4") - [18CrMoS4 Indicative](/materials/din-en/18crmos4 "ISO 18CrMoS4") JIS Japan · 2 - [SCM418 Indicative](/materials/jis/scm418 "JIS SCM418") - [SCM418H Indicative](/materials/jis/scm418h "JIS SCM418H") GOST Russia / CIS · 1 - [20KHM Indicative](/materials/gost/20khm "GOST 20KHM") UNI Italy · 1 - [18CrMo4 Indicative](/materials/din-en/18crmo4 "UNI 18CrMo4") ČSN Czechia · 1 - [15124 Indicative](/materials/csn/15124 "ČSN 15124") STN Slovakia · 1 - [15 124 Indicative](/materials/csn/15124 "STN 15 124") PN Poland · 2 - [15HGM Indicative](/materials/pn/15hgm "PN 15HGM") - [18HGM Indicative](/materials/pn/18hgm "PN 18HGM") MSZ Hungary · 2 - **~BCMo 1 Indicative** - [BCMo 2 Indicative](/materials/msz/bcmo-2 "MSZ BCMo 2") STAS Romania · 1 - [21MoMnCr12 Indicative](/materials/stas/21momncr12 "STAS 21MoMnCr12") 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 Si Iron — the balance, never listed by a standard — 97.4 % Cr — 1.1 % Mn — 0.8 % Si — 0.4 % Traces & impurities · 0.4 % Logarithmic scale, 0.01 % to 100 % — every value here compares directly, decade by decade. | Element | % by weight | |---|---| | C | 0.15–0.21 | | Si | ≤ 0.4 | | Mn | 0.6–0.9 | | P | 0.025 | | S | 0.035 | | Cr | 0.9–1.2 | | Mo | 0.15–0.25 | 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 | 0,15-0,21 | 0.150 | 0.210 | Range | | Si | ≤0,40 | — | 0.400 | Max | | P | 0,025 | 0.025 | 0.025 | Exact | | S | 0,035 | 0.035 | 0.035 | Exact | | Cr | 0,90-1,20 | 0.900 | 1.200 | Range | | Mn | 0,60-0,90 | 0.600 | 0.900 | Range | | 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 Not enough recorded composition to predict a transformation temperature for this grade — missing: Ni. ## 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 7 conditions · 12 values By dimension**Quenching and drawing** source `splav` | Dimension mm | Rm N/mm² | Re N/mm² | A5% | Z% | KCU kJ/m² | |---|---|---|---|---|---| | Ø 15 | 780 | 590 | 12 | 50 | 880 | By thickness**Quenched and tempered** source `steelnumber` | Thickness mm | Rm N/mm² | A% | |---|---|---| | ≤ 160 | 485 – 660 | 20 | By delivery state**no delivery state stated** source `splav` | Delivery state | HB | |---|---| | (annealing) , GOST 4543-71 | 179 | By delivery state**Soft annealed** source `steelnumber` | Delivery state | HB | |---|---| | Soft annealed | 207 | By delivery state**Treated to hardness range** source `steelnumber` | Delivery state | HB | |---|---| | Treated to hardness range | 156 – 207 | By delivery state**Treated to ferrite-pearlite structure and hardness range** source `steelnumber` | Delivery state | HB | |---|---| | Treated to ferrite-pearlite structure and hardness range | 140 – 187 | At temperature**no delivery state stated** source `steelnumber` | Temperature °C | Rm N/mm² | |---|---| | 200 | 1100 | 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. ## Similar grades — and why Selection rule, stated so you can disagree with it: same number class 1.7, a shared category, and a published range for Cr / Mn 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. [20Cr4 1.7027 Cr 0,90-1,20 · Mn 0,60-0,90 - ΔCr 0.00 - ΔMn 0.00 - 25 designations](/materials/din-en/20cr4 "20Cr4")[20CrS4 1.7028 Cr 0,90-1,20 · Mn 0,60-0,90 - ΔCr 0.00 - ΔMn 0.00 - 1 designations](/materials/din-en/20crs4 "20CrS4")[28CrS4 1.7036 Cr 0,90-1,20 · Mn 0,60-0,90 - ΔCr 0.00 - ΔMn 0.00 - 7 designations](/materials/din-en/28crs4 "28CrS4")[18CrMoS4 1.7244 Cr 0,90-1,20 · Mn 0,60-0,90 - ΔCr 0.00 - ΔMn 0.00 - 3 designations](/materials/din-en/18crmos4 "18CrMoS4")[17CrS3 1.7014 Cr 0,70-1,00 · Mn 0,60-0,90 - ΔCr 0.20 - ΔMn 0.00 - 2 designations](/materials/din-en/17crs3 "17CrS3")[17Cr3 1.7016 Cr 0,70-1,00 · Mn 0,60-0,90 - ΔCr 0.20 - ΔMn 0.00 - 36 designations](/materials/din-en/17cr3 "17Cr3") ## 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=8860e2c5-ae93-48e4-a267-54b9cb1f7a8b&designation=e99a4381-b9bf-4319-b536-8970f3ecd18e "Inquiry")[**Datasheet as PDF** Print-ready A4 document **Generating …** **Download started** **Try again**](/materials/msz/bcmo-1.pdf "Datasheet as PDF")