--- title: "F.123 — Quenched and tempered steels" description: "F.123 in UNE: material number 1.5755, also listed as 31NiCr14. Category: Quenched and tempered steels. Designations recorded for this grade: 18." canonical: https://steelequivalents.com/materials/une/f-123 language: en robots: index, follow og_type: website type: material-detail language_alternates: en: https://steelequivalents.com/materials/une/f-123.md cs: https://steelequivalents.com/cs/materiály/une/f-123.md de: https://steelequivalents.com/de/werkstoffe/une/f-123.md es: https://steelequivalents.com/es/materiales/une/f-123.md fr: https://steelequivalents.com/fr/matériaux/une/f-123.md hu: https://steelequivalents.com/hu/anyagok/une/f-123.md it: https://steelequivalents.com/it/materiali/une/f-123.md nl: https://steelequivalents.com/nl/materialen/une/f-123.md pl: https://steelequivalents.com/pl/materiały/une/f-123.md pt: https://steelequivalents.com/pt/materiais/une/f-123.md ru: https://steelequivalents.com/ru/материалы/une/f-123.md tr: https://steelequivalents.com/tr/malzemeler/une/f-123.md zh: https://steelequivalents.com/zh/材料/une/f-123.md ja: https://steelequivalents.com/ja/材料/une/f-123.md ar: https://steelequivalents.com/ar/المواد/une/f-123.md ko: https://steelequivalents.com/ko/재료/une/f-123.md pt-br: https://steelequivalents.com/pt-br/materiais/une/f-123.md hi: https://steelequivalents.com/hi/सामग्री/une/f-123.md content_hash: sha256:08117e27758222b5f71160c6f5412267f2c35a5a7897b7a72816cf711f1833e8 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-123 > Canonical URL: https://steelequivalents.com/materials/une/f-123 > 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 · 18 designations # F.123 F.123 is a designation in UNE for the material held under material number 1.5755, also listed as 31NiCr14. It is a material in the category Quenched and tempered steels. We list 18 designations recorded for this grade, in the standards DIN / EN, BS, AFNOR, UNE, JIS, GOST, ČSN, PN, SRPS and BDS. - [*Material no.* **1.5755**](/materials/material-no/1.5755 "Material no.: 1.5755") - [*Category* **Quenched and tempered steels · 133 grades**](/categories/quenched-and-tempered-steels "Category: Quenched and tempered steels · 133 grades") - *Designations* **18** [Search](/search "Steel grade search")[Inquiry](/inquiry?material=df0af93f-b136-4834-9dbd-ec3bb6ed3b1f&designation=782ae6d6-be81-417b-9f1b-65113ccf9def "Inquiry")[**Datasheet as PDF** Print-ready A4 document **Generating …** **Download started** **Try again**](/materials/une/f-123.pdf "Datasheet as PDF") ## About Quenched and tempered steels Quenched and tempered steels are heat-treated steels designed to combine high strength with useful toughness and ductility. They are used for heavily loaded components such as shafts, gears, fasteners and structural machine parts where resistance to mechanical stress is required. This describes the material class as a whole. Always confirm the individual grade against the standard before ordering. ## Also known as 18 designations · 10 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 - [31NiCr14 This grade’s own name Withdrawn](/materials/din-en/31nicr14 "DIN / EN 31NiCr14") BS United Kingdom · 1 - [653M31 Indicative](/materials/bs/653m31 "BS 653M31") AFNOR France · 4 - [18NC13 Indicative](/materials/afnor/18nc13 "AFNOR 18NC13") - [30NC11 Indicative](/materials/afnor/30nc11 "AFNOR 30NC11") - [30NC11FF Indicative](/materials/afnor/30nc11ff "AFNOR 30NC11FF") - [30NC12 Indicative](/materials/afnor/30nc12 "AFNOR 30NC12") UNE Spain · 1 - **F.123 Indicative** JIS Japan · 2 - [SNC631 Indicative](/materials/jis/snc631 "JIS SNC631") - [SNC836 Indicative](/materials/jis/snc836 "JIS SNC836") GOST Russia / CIS · 5 - [30Kh3MA Indicative](/materials/gost/30kh3ma "GOST 30Kh3MA") - [30Kh3VA Indicative](/materials/gost/30kh3va "GOST 30Kh3VA") - [30KHN3А Indicative](/materials/gost/30khn3a "GOST 30KHN3А") - [30Х3ВА-Ш Indicative](/materials/gost/30kh3va-sh "GOST 30Х3ВА-Ш") - [30ХН3А Indicative](/materials/gost/30khn3a "GOST 30ХН3А") ČSN Czechia · 1 - [16440 Indicative](/materials/csn/16440 "ČSN 16440") PN Poland · 1 - [37HN3A Indicative](/materials/pn/37hn3a "PN 37HN3A") SRPS Serbia · 1 - [Č.5438 Indicative](/materials/srps/c-5438 "SRPS Č.5438") BDS Bulgaria · 1 - [30ChN3A Indicative](/materials/bds/30chn3a "BDS 30ChN3A") 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 Ni Cr Mn Iron — the balance, never listed by a standard — 94.5 % Ni — 3.5 % Cr — 0.8 % Mn — 0.6 % Traces & impurities · 0.6 % Logarithmic scale, 0.01 % to 100 % — every value here compares directly, decade by decade. | Element | % by weight | |---|---| | C | 0.27–0.35 | | Si | 0.15–0.35 | | Mn | 0.4–0.8 | | P | 0.035 | | S | 0.035 | | Cr | 0.55–0.95 | | Ni | 3.25–3.75 | Carbon Silicon Manganese Phosphorus Sulfur Chromium Nickel 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 | 0,27-0,35 | 0.270 | 0.350 | Range | | Si | 0,15-0,35 | 0.150 | 0.350 | Range | | P | 0,035 | 0.035 | 0.035 | Exact | | S | 0,035 | 0.035 | 0.035 | Exact | | Cr | 0,55-0,95 | 0.550 | 0.950 | Range | | Mn | 0,40-0,80 | 0.400 | 0.800 | Range | | Ni | 3,25-3,75 | 3.250 | 3.750 | 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: Mo. ## Physical & mechanical properties Density 7,85 g/cm³ Exact Transformation point Ac1 700 °C Exact Transformation point Ac3 800 °C Exact · Ac3(Acm) Transformation point Ar3 680 °C Exact · Ar3(Arcm) Transformation point Ar1 610 °C Exact Weldability weldable with restrictions As published: limited weldability. Flake sensitivity susceptible As published: predisposed Temper brittleness susceptible As published: predisposed 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 4 conditions · 65 values By dimension**Quenching 850°C, oil, Drawing 200°C, air** source `splav` | Dimension mm | Rm N/mm² | Re N/mm² | A5% | Z% | KCU kJ/m² | |---|---|---|---|---|---| | Ø 5 | 1670 | 1420 | 13 | 50 | 660 | | Ø 20 | 1670 | 1370 | 12 | 45 | 490 | By dimension**Quenching 820°C, oil, Drawing 530°C, water** source `splav` | Dimension mm | Rm N/mm² | Re N/mm² | A5% | Z% | KCU kJ/m² | |---|---|---|---|---|---| | Ø 25 | 980 | 785 | 10 | 50 | 780 | By delivery state**no delivery state stated** source `splav` | Delivery state | HB | |---|---| | (annealing) , GOST 4543-71 | 241 | At temperature**no delivery state stated** source `splav` | Temperature °C | Density g/cm³ | Elastic modulus GPa | Thermal expansion coefficient 10^-6/K | Thermal conductivity W/(m·K) | Specific heat capacity J/(kg·K) | Electrical resistivity nΩ·m | |---|---|---|---|---|---|---| | 20 | 7.85 | 215 | — | 34 | — | 268 | | 100 | 7.83 | 207 | 10.8 | 35 | 494 | 317 | | 200 | 7.8 | 195 | 11.5 | 36 | 504 | 387 | | 300 | 7.77 | 187 | 12.2 | 36 | 518 | 469 | | 400 | 7.73 | 175 | 12.8 | 36 | 536 | 567 | | 500 | 7.7 | 171 | 13.2 | 35 | 558 | 681 | | 600 | 7.67 | — | 13.5 | 31 | 587 | 817 | | 700 | 7.69 | — | — | 28 | 657 | 981 | | 800 | 7.65 | — | — | 27 | 703 | — | | 900 | 7.6 | — | — | — | 695 | — | | 1000 | — | — | — | — | 687 | — | 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. ## 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=df0af93f-b136-4834-9dbd-ec3bb6ed3b1f&designation=782ae6d6-be81-417b-9f1b-65113ccf9def "Inquiry")[**Datasheet as PDF** Print-ready A4 document **Generating …** **Download started** **Try again**](/materials/une/f-123.pdf "Datasheet as PDF")