--- title: "F.1712-31 — Nitriding steels" description: "F.1712-31 in UNE: material number 1.8515, also listed as 31CrMo12. Category: Nitriding steels. Designations recorded for this grade: 15." canonical: https://steelequivalents.com/materials/une/f-1712-31 language: en robots: index, follow og_type: website type: material-detail language_alternates: en: https://steelequivalents.com/materials/une/f-1712-31.md cs: https://steelequivalents.com/cs/materiály/une/f-1712-31.md de: https://steelequivalents.com/de/werkstoffe/une/f-1712-31.md es: https://steelequivalents.com/es/materiales/une/f-1712-31.md fr: https://steelequivalents.com/fr/matériaux/une/f-1712-31.md hu: https://steelequivalents.com/hu/anyagok/une/f-1712-31.md it: https://steelequivalents.com/it/materiali/une/f-1712-31.md nl: https://steelequivalents.com/nl/materialen/une/f-1712-31.md pl: https://steelequivalents.com/pl/materiały/une/f-1712-31.md pt: https://steelequivalents.com/pt/materiais/une/f-1712-31.md ru: https://steelequivalents.com/ru/материалы/une/f-1712-31.md tr: https://steelequivalents.com/tr/malzemeler/une/f-1712-31.md zh: https://steelequivalents.com/zh/材料/une/f-1712-31.md ja: https://steelequivalents.com/ja/材料/une/f-1712-31.md ar: https://steelequivalents.com/ar/المواد/une/f-1712-31.md ko: https://steelequivalents.com/ko/재료/une/f-1712-31.md pt-br: https://steelequivalents.com/pt-br/materiais/une/f-1712-31.md hi: https://steelequivalents.com/hi/सामग्री/une/f-1712-31.md content_hash: sha256:9b395c0df628957e1cff16f14605fbf6c2ddbc61c66717c4f52a1d4d1013c417 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/une/f-1712-31 > Canonical URL: https://steelequivalents.com/materials/une/f-1712-31 > 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. UNE · Spain · 15 designations # F.1712-31 F.1712-31 is a designation in UNE for the material held under material number 1.8515, also listed as 31CrMo12. It is a material in the category Nitriding steels. We list 15 designations recorded for this grade, in the standards DIN / EN, BS, AFNOR, UNE, UNI, SS, ČSN, PN and SRPS. - [*Material no.* **1.8515**](/materials/material-no/1.8515 "Material no.: 1.8515") - [*Category* **Nitriding steels · 11 grades**](/categories/nitriding-steels "Category: Nitriding steels · 11 grades") - *Designations* **15** [Search](/search "Steel grade search")[Inquiry](/inquiry?material=e8591922-942b-46ab-b6b6-a551b6514a6c&designation=41f74899-b754-4fc5-b4f0-34d5656b4417 "Inquiry")[**Datasheet as PDF** Print-ready A4 document **Generating …** **Download started** **Try again**](/materials/une/f-1712-31.pdf "Datasheet as PDF") ## If you came for one of these The most-used names for this grade. - [DIN / EN 31CrMo12 This grade’s own name](/materials/din-en/31crmo12 "DIN / EN 31CrMo12") - [UNE F.1172 This grade’s own name](/materials/une/f-1172 "UNE F.1172") - [SS 2240 This grade’s own name · 2 grades on that route](/materials/ss/2240 "SS 2240") ## About Nitriding steels Nitriding steels are alloy steels designed for nitriding, a surface-hardening treatment that produces a hard, wear-resistant surface while retaining a tough supporting core. They are used for gears, shafts, dies and other components requiring resistance to wear, repeated loading and dimensional change in service. This describes the material class as a whole. Always confirm the individual grade against the standard before ordering. ## Also known as 15 designations · 9 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 - [31CrMo12 This grade’s own name](/materials/din-en/31crmo12 "DIN / EN 31CrMo12") BS United Kingdom · 4 - [40B Indicative](/materials/gb/40b "BS 40B") - [722M24 Indicative](/materials/bs/722m24 "BS 722M24") - [EN40B Indicative](/materials/bs/en40b "BS EN40B") - [HCM5 Indicative](/materials/bs/hcm5 "BS HCM5") AFNOR France · 1 - [30CD12 Indicative](/materials/afnor/30cd12 "AFNOR 30CD12") UNE Spain · 4 - [CrMo12 Indicative](/materials/une/crmo12 "UNE CrMo12") - [F.1172 This grade’s own name](/materials/une/f-1172 "UNE F.1172") - [F.1712 Indicative](/materials/une/f-1712 "UNE F.1712") - **F.1712-31 Indicative** UNI Italy · 1 - [31CrMo12 Indicative](/materials/din-en/31crmo12 "UNI 31CrMo12") SS Sweden · 1 - [2240 This grade’s own name](/materials/ss/2240 "SS 2240") ČSN Czechia · 1 - [15432ŠN Indicative](/materials/csn/15432sn "ČSN 15432ŠN") PN Poland · 1 - [25H3M Indicative](/materials/pn/25h3m "PN 25H3M") SRPS Serbia · 1 - [Č.4738 Indicative](/materials/srps/c-4738 "SRPS Č.4738") 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 — 95.2 % Cr — 3.1 % Mn — 0.6 % Si — 0.4 % Traces & impurities · 0.8 % Logarithmic scale, 0.01 % to 100 % — every value here compares directly, decade by decade. | Element | % by weight | |---|---| | C | 0.28–0.35 | | Si | ≤ 0.4 | | Mn | 0.4–0.7 | | P | 0.025 | | S | 0.035 | | Cr | 2.8–3.3 | | Mo | 0.3–0.5 | 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 | 0,28-0,35 | 0.280 | 0.350 | Range | | Si | ≤0,40 | — | 0.400 | Max | | P | 0,025 | 0.025 | 0.025 | Exact | | S | 0,035 | 0.035 | 0.035 | Exact | | Cr | 2,80-3,30 | 2.800 | 3.300 | Range | | Mn | 0,40-0,70 | 0.400 | 0.700 | Range | | Mo | 0,30-0,50 | 0.300 | 0.500 | 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 7,73 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 2 conditions · 9 values By thickness**Quenched and tempered** source `steelnumber` | Thickness mm | Rm N/mm² | A% | |---|---|---| | 16 – 40 | 1030 – 1230 | 10 | | 40 – 100 | 980 – 1180 | 11 | | 100 – 160 | 930 – 1130 | 12 | | 160 – 250 | 880 – 1080 | 12 | By delivery state**Soft annealed** source `steelnumber` | Delivery state | HB | |---|---| | Soft annealed | 248 | 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 1.8, 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. [1.8523 1.8523 Cr 3,00-3,50 · Mn 0,40-0,70 - ΔCr 0.20 - ΔMn 0.00 - 14 designations](/materials/material-no/1.8523 "1.8523") ## 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=e8591922-942b-46ab-b6b6-a551b6514a6c&designation=41f74899-b754-4fc5-b4f0-34d5656b4417 "Inquiry")[**Datasheet as PDF** Print-ready A4 document **Generating …** **Download started** **Try again**](/materials/une/f-1712-31.pdf "Datasheet as PDF")