--- title: "51Si7 — Spring steels" description: "51Si7: 9 equivalent designations across 6 standards, with the recorded chemical composition shown next to the source text." canonical: https://steelequivalents.com/materials/din-en/51si7 language: en robots: index, follow og_type: website type: material-detail language_alternates: en: https://steelequivalents.com/materials/din-en/51si7.md cs: https://steelequivalents.com/cs/materiály/din-en/51si7.md de: https://steelequivalents.com/de/werkstoffe/din-en/51si7.md es: https://steelequivalents.com/es/materiales/din-en/51si7.md fr: https://steelequivalents.com/fr/matériaux/din-en/51si7.md hu: https://steelequivalents.com/hu/anyagok/din-en/51si7.md it: https://steelequivalents.com/it/materiali/din-en/51si7.md nl: https://steelequivalents.com/nl/materialen/din-en/51si7.md pl: https://steelequivalents.com/pl/materiały/din-en/51si7.md pt: https://steelequivalents.com/pt/materiais/din-en/51si7.md ru: https://steelequivalents.com/ru/материалы/din-en/51si7.md tr: https://steelequivalents.com/tr/malzemeler/din-en/51si7.md zh: https://steelequivalents.com/zh/材料/din-en/51si7.md ja: https://steelequivalents.com/ja/材料/din-en/51si7.md ar: https://steelequivalents.com/ar/المواد/din-en/51si7.md ko: https://steelequivalents.com/ko/재료/din-en/51si7.md pt-br: https://steelequivalents.com/pt-br/materiais/din-en/51si7.md hi: https://steelequivalents.com/hi/सामग्री/din-en/51si7.md content_hash: sha256:8734f8a6c708e2cae4906d711c5eda6a72c21f2565ac5e3383a5f6a6380c7327 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/din-en/51si7 > Canonical URL: https://steelequivalents.com/materials/din-en/51si7 > 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. DIN / EN · Europe · 9 designations # 51Si7 51Si7 is a material in the category [Spring steels](/categories/spring-steels "Spring steels"), held under material number 1.5025. We list 8 designations recorded for this grade, in the standards UNS, AISI / SAE, GOST, PN and SRPS. Its recorded composition includes C 0.47–0.55%, Si 1.5–1.8%, P 0.045%, S 0.045% and Mn 0.5–0.8%. Its recorded density is 7.85 g/cm³. - [*Material no.* **1.5025**](/materials/material-no/1.5025 "Material no.: 1.5025") - [*Category* **Spring steels · 52 grades**](/categories/spring-steels "Category: Spring steels · 52 grades") - *Designations* **9** [Search](/search "Steel grade search")[Inquiry](/inquiry?material=15f01fc7-6712-4e93-8894-978c88aef7f8&designation=34bc218d-9d07-43e7-b8c0-c74c96696293 "Inquiry")[**Datasheet as PDF** Print-ready A4 document **Generating …** **Download started** **Try again**](/materials/din-en/51si7.pdf "Datasheet as PDF") ## If you came for one of these The most-used names for this grade. - [UNS G92550 This grade’s own name · 2 grades on that route](/materials/uns/g92550 "UNS G92550") - [AISI / SAE 9255 This grade’s own name · 2 grades on that route](/materials/aisi-sae/9255 "AISI / SAE 9255") ## About Spring steels Spring steels are alloy steels designed to store and release elastic energy repeatedly without permanent deformation. They are characterised by a combination of strength, hardness and resilience, making them suitable for springs, clips, washers and other components subjected to repeated flexing or shock. This describes the material class as a whole. Always confirm the individual grade against the standard before ordering. ## Also known as 9 designations · 6 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 - **51Si7 This grade’s own name** UNS United States · 1 - [G92550 This grade’s own name](/materials/uns/g92550 "UNS G92550") AISI / SAE United States · 1 - [9255 This grade’s own name](/materials/aisi-sae/9255 "AISI / SAE 9255") GOST Russia / CIS · 2 - [40С2 Indicative](/materials/gost/40s2 "GOST 40С2") - [55С2 Indicative](/materials/gost/55s2 "GOST 55С2") PN Poland · 3 - [40S2 Indicative](/materials/gost/40s2 "PN 40S2") - [50S2 Indicative](/materials/gost/50s2 "PN 50S2") - [55S2 Indicative](/materials/gost/55s2 "PN 55S2") SRPS Serbia · 1 - [Č.2132 Indicative](/materials/srps/c-2132 "SRPS Č.2132") Every designation on file is listed — no truncation, no “+ n more”. Each one is itself a route that leads back here. ## Chemical composition 6 elements on file · weight % What this alloy is Fe Si Mn C Iron — the balance, never listed by a standard — 97.1 % Si — 1.7 % Mn — 0.7 % C — 0.5 % Traces & impurities · 0.1 % Logarithmic scale, 0.01 % to 100 % — every value here compares directly, decade by decade. | Element | % by weight | |---|---| | C | 0.47–0.55 | | Si | 1.5–1.8 | | Mn | 0.5–0.8 | | P | 0.045 | | S | 0.045 | | N | 0.007 | Carbon Silicon Manganese Phosphorus Sulfur Nitrogen 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 | 0,47-0,55 | 0.470 | 0.550 | Range | | N | 0,007 | 0.007 | 0.007 | Exact | | Si | 1,50-1,80 | 1.500 | 1.800 | Range | | P | 0,045 | 0.045 | 0.045 | Exact | | S | 0,045 | 0.045 | 0.045 | Exact | | Mn | 0,50-0,80 | 0.500 | 0.800 | 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, Cr, Mo. ## 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. ## Similar grades — and why Selection rule, stated so you can disagree with it: same number class 1.5, a shared category, and a published range for Si / 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. [38Si7 1.5023 Si 1,50-1,80 · Mn 0,50-0,80 - ΔSi 0.00 - ΔMn 0.00 - 7 designations](/materials/din-en/38si7 "38Si7")[46Si7 1.5024 Si 1,50-1,80 · Mn 0,50-0,80 - ΔSi 0.00 - ΔMn 0.00 - 11 designations](/materials/din-en/46si7 "46Si7")[71Si7 1.5029 Si 1,50-1,80 · Mn 0,60-0,80 - ΔSi 0.00 - ΔMn 0.05 - 1 designations](/materials/din-en/71si7 "71Si7")[38Si6 1.5022 Si 1,40-1,60 · Mn 0,50-0,80 - ΔSi 0.15 - ΔMn 0.00 - 1 designations](/materials/din-en/38si6 "38Si6")[60Si7 1.5027 Si 1,50-1,80 · Mn 0,70-1,00 - ΔSi 0.00 - ΔMn 0.20 - 18 designations](/materials/din-en/60si7 "60Si7")[65Si7 1.5028 Si 1,50-1,80 · Mn 0,70-1,00 - ΔSi 0.00 - ΔMn 0.20 - 17 designations](/materials/din-en/65si7 "65Si7") ## 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=15f01fc7-6712-4e93-8894-978c88aef7f8&designation=34bc218d-9d07-43e7-b8c0-c74c96696293 "Inquiry")[**Datasheet as PDF** Print-ready A4 document **Generating …** **Download started** **Try again**](/materials/din-en/51si7.pdf "Datasheet as PDF")