--- title: "A666 — 23 equivalent grades, compared" description: "The designation A666 is carried by 23 different grades. Compare them on the elements that actually differ, then open the one your print means." canonical: https://steelequivalents.com/materials/astm/a666 language: en robots: index, follow og_type: website type: material-detail language_alternates: en: https://steelequivalents.com/materials/astm/a666.md cs: https://steelequivalents.com/cs/materiály/astm/a666.md de: https://steelequivalents.com/de/werkstoffe/astm/a666.md es: https://steelequivalents.com/es/materiales/astm/a666.md fr: https://steelequivalents.com/fr/matériaux/astm/a666.md hu: https://steelequivalents.com/hu/anyagok/astm/a666.md it: https://steelequivalents.com/it/materiali/astm/a666.md nl: https://steelequivalents.com/nl/materialen/astm/a666.md pl: https://steelequivalents.com/pl/materiały/astm/a666.md pt: https://steelequivalents.com/pt/materiais/astm/a666.md ru: https://steelequivalents.com/ru/материалы/astm/a666.md tr: https://steelequivalents.com/tr/malzemeler/astm/a666.md zh: https://steelequivalents.com/zh/材料/astm/a666.md ja: https://steelequivalents.com/ja/材料/astm/a666.md ar: https://steelequivalents.com/ar/المواد/astm/a666.md ko: https://steelequivalents.com/ko/재료/astm/a666.md pt-br: https://steelequivalents.com/pt-br/materiais/astm/a666.md hi: https://steelequivalents.com/hi/सामग्री/astm/a666.md content_hash: sha256:343b336da001452aae3011e60b73b2a10602e7b1e830cfea25806e9bbb4509d9 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/astm/a666 > Canonical URL: https://steelequivalents.com/materials/astm/a666 > 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. ASTM · United States · 23 grades # A666 The designation A666 is carried by 23 different grades. Compare them on the elements that actually differ, then open the one your print means. - *Matching grades* **23** - [*Category* **Non-magnetic steels · 31 grades**](/categories/non-magnetic-steels "Category: Non-magnetic steels · 31 grades") - [*Category* **Stainless steels · 468 grades**](/categories/stainless-steels "Category: Stainless steels · 468 grades") - [*Category* **Special steels for aviation and aerospace · 39 grades**](/categories/special-steels-for-aviation-and-aerospace "Category: Special steels for aviation and aerospace · 39 grades") - [*Category* **Others · 1754 grades**](/categories/others "Category: Others · 1754 grades") - [*Category* **Heat resistant steels · 64 grades**](/categories/heat-resistant-steels "Category: Heat resistant steels · 64 grades") - [*Category* **High-temperature steels / aviation variant · 12 grades**](/categories/high-temperature-steels-aviation-variant "Category: High-temperature steels / aviation variant · 12 grades") - [*Category* **Low-temperature steels · 4 grades**](/categories/low-temperature-steels "Category: Low-temperature steels · 4 grades") [Search](/search "Steel grade search")[Inquiry](/inquiry "Inquiry") ## Which of the 23 do you want? This name is carried by several grades. The elements shown are the ones whose values actually differ across the set — the ones that decide the question. Values are the source text verbatim; an em dash means no value on file for that element on that grade, not zero. | Grade | Material no. | Category | Designations | Ni% | C% | Cr% | N% | Mn% | Mo% | |---|---|---|---|---|---|---|---|---|---| | [X8CrMnNi18-8](/materials/din-en/x8crmnni18-8 "X8CrMnNi18-8") | [1.3965](/materials/material-no/1.3965 "1.3965") 1.3 | [Non-magnetic steels](/categories/non-magnetic-steels "Non-magnetic steels") | 24 | 4,50-6,50 | ≤0,10 | 17,0-19,0 | 0,10-0,20 | 7,50-9,50 | — | | [X 12 CrNi 18 8](/materials/din-en/x-12-crni-18-8 "X 12 CrNi 18 8") | [1.4300](/materials/material-no/1.4300 "1.4300") 1.4 | [Stainless steels](/categories/stainless-steels "Stainless steels") | 76 | 8,00-10,0 | ≤0,12 | 17,0-19,0 | — | ≤2,00 | — | | [1.4301](/materials/material-no/1.4301 "1.4301") | [1.4301](/materials/material-no/1.4301 "1.4301") 1.4 | [Stainless steels](/categories/stainless-steels "Stainless steels") | 170 | 8,00-10,5 | ≤0,07 | 17,5-19,5 | 0,11 | ≤2,00 | — | | [1.4306](/materials/material-no/1.4306 "1.4306") | [1.4306](/materials/material-no/1.4306 "1.4306") 1.4 | [Stainless steels](/categories/stainless-steels "Stainless steels") | 137 | 10,0-12,0 | ≤0,030 | 18,0-20,0 | 0,11 | ≤2,00 | — | | [1.4307](/materials/material-no/1.4307 "1.4307") | [1.4307](/materials/material-no/1.4307 "1.4307") 1.4 | [Stainless steels](/categories/stainless-steels "Stainless steels") | 88 | 8,00-10,5 | ≤0,030 | 17,5-19,5 | 0,11 | ≤2,00 | — | | [1.4310](/materials/material-no/1.4310 "1.4310") | [1.4310](/materials/material-no/1.4310 "1.4310") 1.4 | [Stainless steels](/categories/stainless-steels "Stainless steels") | 97 | 6,00-9,50 | 0,05-0,15 | 16,0-19,0 | 0,11 | ≤2,00 | ≤0,80 | | [1.4311](/materials/material-no/1.4311 "1.4311") | [1.4311](/materials/material-no/1.4311 "1.4311") 1.4 | [Stainless steels](/categories/stainless-steels "Stainless steels") | 55 | 8,50-11,50 | ≤0,030 | 17,5-19,5 | 0,12-0,22 | ≤2,00 | — | | [S30400](/materials/uns/s30400 "S30400") | [1.4314](/materials/material-no/1.4314 "1.4314") 1.4 | [Special steels for aviation and aerospace](/categories/special-steels-for-aviation-and-aerospace "Special steels for aviation and aerospace") | 86 | 8,50-10,5 | ≤0,07 | 17,0-19,0 | — | ≤2,00 | — | | [X5CrNiN19-9](/materials/din-en/x5crnin19-9 "X5CrNiN19-9") | [1.4315](/materials/material-no/1.4315 "1.4315") 1.4 | [Stainless steels](/categories/stainless-steels "Stainless steels") | 26 | 8,00-11,0 | ≤0,06 | 18,0-20,0 | 0,12-0,22 | ≤2,00 | — | | [X3CrNiN17-8](/materials/din-en/x3crnin17-8 "X3CrNiN17-8") | [1.4319](/materials/material-no/1.4319 "1.4319") 1.4 | [Stainless steels](/categories/stainless-steels "Stainless steels") | 23 | 6,00-8,00 | ≤0,070 | 16,0-18,0 | 0,11 | ≤2,00 | — | | [S30100](/materials/uns/s30100 "S30100") | [1.4324](/materials/material-no/1.4324 "1.4324") 1.4 | [Special steels for aviation and aerospace](/categories/special-steels-for-aviation-and-aerospace "Special steels for aviation and aerospace") | 52 | 7,00-9,00 | ≤0,12 | 16,0-18,0 | — | ≤2,00 | — | | [X9CrNi18-9](/materials/din-en/x9crni18-9 "X9CrNi18-9") | [1.4325](/materials/material-no/1.4325 "1.4325") 1.4 | [Stainless steels](/categories/stainless-steels "Stainless steels") | 51 | 8,00-10,0 | 0,03-0,15 | 17,0-19,0 | — | ≤2,00 | — | | [X12CrMnNiN17-7-5](/materials/din-en/x12crmnnin17-7-5 "X12CrMnNiN17-7-5") | [1.4372](/materials/material-no/1.4372 "1.4372") 1.4 | [Others](/categories/others "Others") | 27 | 3,50-5,50 | ≤0,15 | 16,0-18,0 | 0,05-0,25 | 5,50-7,50 | — | | [X12CrMnNiN18-9-5](/materials/din-en/x12crmnnin18-9-5 "X12CrMnNiN18-9-5") | [1.4373](/materials/material-no/1.4373 "1.4373") 1.4 | [Non-magnetic steels](/categories/non-magnetic-steels "Non-magnetic steels") | 31 | 4,00-6,00 | ≤0,15 | 17,0-19,0 | 0,05-0,25 | 7,50-10,5 | — | | [1.4401](/materials/material-no/1.4401 "1.4401") | [1.4401](/materials/material-no/1.4401 "1.4401") 1.4 | [Stainless steels](/categories/stainless-steels "Stainless steels") | 134 | 10,0-13,0 | ≤0,07 | 16,5-18,5 | 0,11 | ≤2,00 | 2,00-2,50 | | [1.4404](/materials/material-no/1.4404 "1.4404") | [1.4404](/materials/material-no/1.4404 "1.4404") 1.4 | [Stainless steels](/categories/stainless-steels "Stainless steels") | 147 | 10,0-13,0 | ≤0,030 | 16,5-18,2 | 0,11 | ≤2,00 | 2,00-2,50 | | [X2CrNiMo17-12-3](/materials/din-en/x2crnimo17-12-3 "X2CrNiMo17-12-3") | [1.4432](/materials/material-no/1.4432 "1.4432") 1.4 | [Others](/categories/others "Others") | 66 | 10,5-13,0 | ≤0,030 | 16,5-18,5 | 0,11 | ≤2,00 | 2,50-3,00 | | [1.4435](/materials/material-no/1.4435 "1.4435") | [1.4435](/materials/material-no/1.4435 "1.4435") 1.4 | [Stainless steels](/categories/stainless-steels "Stainless steels") | 99 | 12,5-15,0 | ≤0,030 | 17,0-19,0 | 0,11 | ≤2,00 | 2,50-3,00 | | [1.4436](/materials/material-no/1.4436 "1.4436") | [1.4436](/materials/material-no/1.4436 "1.4436") 1.4 | [Stainless steels](/categories/stainless-steels "Stainless steels") | 118 | 10,5-13,0 | ≤0,05 | 16,5-18,5 | 0,11 | ≤2,00 | 2,50-3,00 | | [X6CrNiMoN17-12-3](/materials/din-en/x6crnimon17-12-3 "X6CrNiMoN17-12-3") | [1.4495](/materials/material-no/1.4495 "1.4495") 1.4 | [Others](/categories/others "Others") | 25 | 10,0-14,0 | ≤0,08 | 16,0-18,0 | 0,10-0,22 | ≤2,00 | 2,00-3,00 | | [1.4828](/materials/material-no/1.4828 "1.4828") | [1.4828](/materials/material-no/1.4828 "1.4828") 1.4 | [Heat resistant steels](/categories/heat-resistant-steels "Heat resistant steels") | 77 | 11,0-13,0 | ≤0,20 | 19,0-21,0 | 0,11 | ≤2,00 | — | | [S31600](/materials/uns/s31600 "S31600") | [1.4984](/materials/material-no/1.4984 "1.4984") 1.4 | [High-temperature steels / aviation variant](/categories/high-temperature-steels-aviation-variant "High-temperature steels / aviation variant") | 64 | 15,5-17,5 | 0,04-0,10 | 15,5-17,5 | — | ≤1,50 | 1,60-2,00 | | [X3CrNiN18-10](/materials/din-en/x3crnin18-10 "X3CrNiN18-10") | [1.6907](/materials/material-no/1.6907 "1.6907") 1.6 | [Low-temperature steels](/categories/low-temperature-steels "Low-temperature steels") | 26 | 9,00-11,5 | ≤0,04 | 17,0-19,0 | 0,10-0,18 | ≤2,00 | — | ## Not sure which one your print means? 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 "Inquiry")