--- title: "SNi6601 — Heat resistant steels" description: "SNi6601 in ISO: material number 2.4851, also listed as NiCr23Fe. Category: Heat resistant steels. Designations recorded for this grade: 21." canonical: https://steelequivalents.com/materials/iso/sni6601 language: en robots: index, follow og_type: website type: material-detail language_alternates: en: https://steelequivalents.com/materials/iso/sni6601.md cs: https://steelequivalents.com/cs/materiály/iso/sni6601.md de: https://steelequivalents.com/de/werkstoffe/iso/sni6601.md es: https://steelequivalents.com/es/materiales/iso/sni6601.md fr: https://steelequivalents.com/fr/matériaux/iso/sni6601.md hu: https://steelequivalents.com/hu/anyagok/iso/sni6601.md it: https://steelequivalents.com/it/materiali/iso/sni6601.md nl: https://steelequivalents.com/nl/materialen/iso/sni6601.md pl: https://steelequivalents.com/pl/materiały/iso/sni6601.md pt: https://steelequivalents.com/pt/materiais/iso/sni6601.md ru: https://steelequivalents.com/ru/материалы/iso/sni6601.md tr: https://steelequivalents.com/tr/malzemeler/iso/sni6601.md zh: https://steelequivalents.com/zh/材料/iso/sni6601.md ja: https://steelequivalents.com/ja/材料/iso/sni6601.md ar: https://steelequivalents.com/ar/المواد/iso/sni6601.md ko: https://steelequivalents.com/ko/재료/iso/sni6601.md pt-br: https://steelequivalents.com/pt-br/materiais/iso/sni6601.md hi: https://steelequivalents.com/hi/सामग्री/iso/sni6601.md content_hash: sha256:32da6348811a793862fed99c0ff6456437e9b0be4910bae91eaf07ba3d8da017 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/iso/sni6601 > Canonical URL: https://steelequivalents.com/materials/iso/sni6601 > 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. ISO · International · 21 designations # SNi6601 SNi6601 is a designation in ISO for the material held under material number 2.4851, also listed as NiCr23Fe. It is a material in the category Heat resistant steels. We list 21 designations recorded for this grade, in the standards DIN / EN, UNS, ASTM, BS, ISO, SAE AMS, JIS and GB. - [*Material no.* **2.4851**](/materials/material-no/2.4851 "Material no.: 2.4851") - [*Category* **Heat resistant steels · 64 grades**](/categories/heat-resistant-steels "Category: Heat resistant steels · 64 grades") - *Designations* **21** [Search](/search "Steel grade search")[Inquiry](/inquiry?material=a0c1a348-47e5-4a72-862f-01785208a2e1&designation=5ebd509b-2c10-4f4a-a76f-281fe1e8fd24 "Inquiry")[**Datasheet as PDF** Print-ready A4 document **Generating …** **Download started** **Try again**](/materials/iso/sni6601.pdf "Datasheet as PDF") ## If you came for one of these The most-used names for this grade. - [DIN / EN NiCr23Fe This grade’s own name](/materials/din-en/nicr23fe "DIN / EN NiCr23Fe") - [UNS N06601 This grade’s own name · 3 grades on that route](/materials/uns/n06601 "UNS N06601") ## About Heat resistant steels Heat resistant steels are alloyed materials designed to retain useful mechanical properties and resist oxidation or scaling during service at elevated temperatures. They are used for components in furnaces, boilers, heat exchangers and power-generation equipment exposed to hot gases or sustained heat. This describes the material class as a whole. Always confirm the individual grade against the standard before ordering. ## Also known as 21 designations · 8 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 - [NiCr23Fe This grade’s own name](/materials/din-en/nicr23fe "DIN / EN NiCr23Fe") UNS United States · 1 - [N06601 This grade’s own name](/materials/uns/n06601 "UNS N06601") ASTM United States · 8 - [B163 Indicative](/materials/astm/b163 "ASTM B163") - [B166 Indicative](/materials/astm/b166 "ASTM B166") - [B167 Indicative](/materials/astm/b167 "ASTM B167") - [B168 Indicative](/materials/astm/b168 "ASTM B168") - [B564 Indicative](/materials/astm/b564 "ASTM B564") - [B751 Indicative](/materials/astm/b751 "ASTM B751") - [B775 Indicative](/materials/astm/b775 "ASTM B775") - [B829 Indicative](/materials/astm/b829 "ASTM B829") BS United Kingdom · 1 - [BS2901 NA49 Indicative](/materials/bs/bs2901-na49 "BS BS2901 NA49") ISO International · 4 - [Ni6601 Indicative](/materials/iso/ni6601 "ISO Ni6601") - [NiCr23Fe15Al Indicative](/materials/din-en/nicr23fe15al "ISO NiCr23Fe15Al") - [NW6601 Indicative](/materials/iso/nw6601 "ISO NW6601") - **SNi6601 Indicative** SAE AMS United States / Aerospace · 2 - [5715 Indicative bar forging ring](/materials/ams/5715 "SAE AMS 5715") - [5870 Indicative plate sheet strip](/materials/ams/5870 "SAE AMS 5870") JIS Japan · 1 - [NCF601 Indicative](/materials/jis/ncf601 "JIS NCF601") GB China · 3 - [H06601 Indicative](/materials/gb/h06601 "GB H06601") - [HNS3103 Indicative](/materials/gb/hns3103 "GB HNS3103") - [NS3103 Indicative](/materials/gb/ns3103 "GB NS3103") Every designation on file is listed — no truncation, no “+ n more”. Each one is itself a route that leads back here. ## Chemical composition 13 elements on file · weight % What this alloy is Fe Ni Cr Co Iron — the balance, never listed by a standard — 11 % Ni — 60.5 % Cr — 23 % Co — 1.5 % Traces & impurities · 4 % Logarithmic scale, 0.01 % to 100 % — every value here compares directly, decade by decade. | Element | % by weight | |---|---| | C | 0.03–0.1 | | Si | ≤ 0.5 | | Mn | ≤ 1 | | P | 0.02 | | S | 0.015 | | Cr | 21–25 | | Ni | 58–63 — Unusual | | Co | ≤ 1.5 | | Cu | ≤ 0.5 | | Al | 1–1.7 | | Ti | ≤ 0.5 | | B | ≤ 0.006 | | Fe | ≤ 18 | Carbon Silicon Manganese Phosphorus Sulfur Chromium Nickel Cobalt Copper Aluminium Titanium Boron Iron 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 | |---|---|---|---|---| | B | ≤0,006 | — | 0.006 | Max | | C | 0,03-0,10 | 0.030 | 0.100 | Range | | Al | 1,00-1,70 | 1.000 | 1.700 | Range | | Si | ≤0,50 | — | 0.500 | Max | | P | 0,02 | 0.020 | 0.020 | Exact | | S | 0,015 | 0.015 | 0.015 | Exact | | Ti | ≤0,50 | — | 0.500 | Max | | Cr | 21,0-25,0 | 21.000 | 25.000 | Range | | Mn | ≤1,00 | — | 1.000 | Max | | Fe | ≤18,0 | — | 18.000 | Max | | Co | ≤1,50 | — | 1.500 | Max | | Ni | 58,0-63,0 | 58.000 | 63.000 | Range | | Cu | ≤0,50 | — | 0.500 | Max | 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 8,2 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 1 conditions · 1 values By delivery state**Solution annealed** source `steelnumber` | Delivery state | HB | |---|---| | Solution annealed | 220 | 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 2.4, a shared category, and a published range for Ni / Cr 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. [NiCr22Mo9Nb 2.4856 Ni ≥58,0 · Cr 20,0-23,0 - ΔNi 2.50 - ΔCr 1.50 - 24 designations](/materials/din-en/nicr22mo9nb "NiCr22Mo9Nb") ## 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=a0c1a348-47e5-4a72-862f-01785208a2e1&designation=5ebd509b-2c10-4f4a-a76f-281fe1e8fd24 "Inquiry")[**Datasheet as PDF** Print-ready A4 document **Generating …** **Download started** **Try again**](/materials/iso/sni6601.pdf "Datasheet as PDF")