--- title: "MT309 — Heat resistant steels" description: "MT309 in AISI / SAE: material number 1.4833, also listed as X12CrNi23-13. Category: Heat resistant steels. Designations recorded for this grade: 69." canonical: https://steelequivalents.com/materials/aisi-sae/mt309 language: en robots: index, follow og_type: website type: material-detail language_alternates: en: https://steelequivalents.com/materials/aisi-sae/mt309.md cs: https://steelequivalents.com/cs/materiály/aisi-sae/mt309.md de: https://steelequivalents.com/de/werkstoffe/aisi-sae/mt309.md es: https://steelequivalents.com/es/materiales/aisi-sae/mt309.md fr: https://steelequivalents.com/fr/matériaux/aisi-sae/mt309.md hu: https://steelequivalents.com/hu/anyagok/aisi-sae/mt309.md it: https://steelequivalents.com/it/materiali/aisi-sae/mt309.md nl: https://steelequivalents.com/nl/materialen/aisi-sae/mt309.md pl: https://steelequivalents.com/pl/materiały/aisi-sae/mt309.md pt: https://steelequivalents.com/pt/materiais/aisi-sae/mt309.md ru: https://steelequivalents.com/ru/материалы/aisi-sae/mt309.md tr: https://steelequivalents.com/tr/malzemeler/aisi-sae/mt309.md zh: https://steelequivalents.com/zh/材料/aisi-sae/mt309.md ja: https://steelequivalents.com/ja/材料/aisi-sae/mt309.md ar: https://steelequivalents.com/ar/المواد/aisi-sae/mt309.md ko: https://steelequivalents.com/ko/재료/aisi-sae/mt309.md pt-br: https://steelequivalents.com/pt-br/materiais/aisi-sae/mt309.md hi: https://steelequivalents.com/hi/सामग्री/aisi-sae/mt309.md content_hash: sha256:920917d580efca7f8dadd540d523565f01802bbbceadeb8e4cf36c5d05ee5b24 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/aisi-sae/mt309 > Canonical URL: https://steelequivalents.com/materials/aisi-sae/mt309 > 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. AISI / SAE · United States · 69 designations # MT309 MT309 is a designation in AISI / SAE for the material held under material number 1.4833, also listed as X12CrNi23-13. It is a material in the category Heat resistant steels. We list 69 designations recorded for this grade, in the standards DIN / EN, UNS, AISI / SAE, ASTM, BS, AFNOR, UNE, ISO, SAE AMS, JIS, GB, GOST, UNI, PN, STAS and KS. - [*Material no.* **1.4833**](/materials/material-no/1.4833 "Material no.: 1.4833") - [*Category* **Heat resistant steels · 64 grades**](/categories/heat-resistant-steels "Category: Heat resistant steels · 64 grades") - *Designations* **69** [Search](/search "Steel grade search")[Inquiry](/inquiry?material=4ad5b983-4150-4491-9e47-83a57bc065d4&designation=d2a3abc1-c930-46e1-a365-ab122a500a61 "Inquiry")[**Datasheet as PDF** Print-ready A4 document **Generating …** **Download started** **Try again**](/materials/aisi-sae/mt309.pdf "Datasheet as PDF") ## If you came for one of these The most-used names for this grade. - [DIN / EN X12CrNi23-13 This grade’s own name](/materials/din-en/x12crni23-13 "DIN / EN X12CrNi23-13") - [UNS S30908 This grade’s own name · 2 grades on that route](/materials/uns/s30908 "UNS S30908") - [AISI / SAE 309S This grade’s own name · 3 grades on that route](/materials/aisi-sae/309s "AISI / SAE 309S") ## 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 69 designations · 16 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 · 3 - [X 7 CrNi 23 14 This grade’s own name Withdrawn](/materials/din-en/x-7-crni-23-14 "DIN / EN X 7 CrNi 23 14") - [X12CrNi23-13 This grade’s own name](/materials/din-en/x12crni23-13 "DIN / EN X12CrNi23-13") - [X18CrNi23-13 This grade’s own name](/materials/din-en/x18crni23-13 "DIN / EN X18CrNi23-13") UNS United States · 2 - [S30900 Indicative](/materials/uns/s30900 "UNS S30900") - [S30908 This grade’s own name](/materials/uns/s30908 "UNS S30908") AISI / SAE United States · 8 - [30309 Indicative](/materials/aisi-sae/30309 "AISI / SAE 30309") - [30309S Indicative](/materials/aisi-sae/30309s "AISI / SAE 30309S") - [309 Indicative](/materials/aisi-sae/309 "AISI / SAE 309") - [309S This grade’s own name](/materials/aisi-sae/309s "AISI / SAE 309S") - **MT309 Indicative** - [MT309S Indicative](/materials/aisi-sae/mt309s "AISI / SAE MT309S") - [S30900 Indicative](/materials/uns/s30900 "AISI / SAE S30900") - [S30908 Indicative](/materials/uns/s30908 "AISI / SAE S30908") ASTM United States · 24 - [A1012 Indicative](/materials/astm/a1012 "ASTM A1012") - [A167 Indicative](/materials/astm/a167 "ASTM A167") - [A213 Indicative](/materials/astm/a213 "ASTM A213") - [A240 Indicative](/materials/astm/a240 "ASTM A240") - [A249 Indicative](/materials/astm/a249 "ASTM A249") - [A264 Indicative](/materials/astm/a264 "ASTM A264") - [A276 Indicative](/materials/astm/a276 "ASTM A276") - [A312 Indicative](/materials/astm/a312 "ASTM A312") - [A314 Indicative](/materials/astm/a314 "ASTM A314") - [A358 Indicative](/materials/astm/a358 "ASTM A358") - [A403 Indicative](/materials/astm/a403 "ASTM A403") - [A409 Indicative](/materials/astm/a409 "ASTM A409") - [A473 Indicative](/materials/astm/a473 "ASTM A473") - [A478 Indicative](/materials/astm/a478 "ASTM A478") - [A479 Indicative](/materials/astm/a479 "ASTM A479") - [A480 Indicative](/materials/astm/a480 "ASTM A480") - [A511 Indicative](/materials/astm/a511 "ASTM A511") - [A554 Indicative](/materials/astm/a554 "ASTM A554") - [A580 Indicative](/materials/astm/a580 "ASTM A580") - [A813 Indicative](/materials/astm/a813 "ASTM A813") - [A814 Indicative](/materials/astm/a814 "ASTM A814") - [A924 Indicative](/materials/astm/a924 "ASTM A924") - [A943 Indicative](/materials/astm/a943 "ASTM A943") - [F2281 Indicative](/materials/astm/f2281 "ASTM F2281") BS United Kingdom · 4 - [309S Indicative](/materials/aisi-sae/309s "BS 309S") - [309S16 Indicative](/materials/bs/309s16 "BS 309S16") - [309S24 Indicative](/materials/bs/309s24 "BS 309S24") - [X12CrNi23-13 Indicative](/materials/din-en/x12crni23-13 "BS X12CrNi23-13") AFNOR France · 4 - [Z10CNS20-12 Indicative](/materials/afnor/z10cns20-12 "AFNOR Z10CNS20-12") - [Z15CN23-13 Indicative](/materials/afnor/z15cn23-13 "AFNOR Z15CN23-13") - [Z15CN24-13 Indicative](/materials/afnor/z15cn24-13 "AFNOR Z15CN24-13") - [Z17CNS20-12 Indicative](/materials/afnor/z17cns20-12 "AFNOR Z17CNS20-12") UNE Spain · 1 - [X12CrNi23-13 Indicative](/materials/din-en/x12crni23-13 "UNE X12CrNi23-13") ISO International · 1 - [X6CrNi23-14 Indicative](/materials/iso/x6crni23-14 "ISO X6CrNi23-14") SAE AMS United States / Aerospace · 4 - [5523 Indicative](/materials/ams/5523 "SAE AMS 5523") - [5574 Indicative](/materials/ams/5574 "SAE AMS 5574") - [5650 Indicative](/materials/ams/5650 "SAE AMS 5650") - [7490 Indicative](/materials/ams/7490 "SAE AMS 7490") JIS Japan · 5 - [SUH 309 Indicative](/materials/jis/suh-309 "JIS SUH 309") - [SUS 309S Indicative](/materials/jis/sus309s "JIS SUS 309S") - [SUS 309STP Indicative](/materials/jis/sus309stp "JIS SUS 309STP") - [SUS309 Indicative](/materials/jis/sus309 "JIS SUS309") - [SUS309STB Indicative](/materials/jis/sus309stb "JIS SUS309STB") GB China · 2 - [0Cr23Ni13 Indicative](/materials/gb/0cr23ni13 "GB 0Cr23Ni13") - [2Cr23Ni13 Indicative](/materials/gb/2cr23ni13 "GB 2Cr23Ni13") GOST Russia / CIS · 4 - [20KH23N13 Indicative](/materials/gost/20kh23n13 "GOST 20KH23N13") - [20Х23Н13 Indicative](/materials/gost/20kh23n13 "GOST 20Х23Н13") - [Х23Н13 Indicative](/materials/gost/kh23n13 "GOST Х23Н13") - [ЭИ319 Indicative](/materials/gost/ei319 "GOST ЭИ319") UNI Italy · 2 - [X16CrNi23-14 Indicative](/materials/uni/x16crni23-14 "UNI X16CrNi23-14") - [X6CrNi2314 Indicative](/materials/iso/x6crni23-14 "UNI X6CrNi2314") PN Poland · 3 - [H18N9S Indicative](/materials/pn/h18n9s "PN H18N9S") - [H20N12S2 Indicative](/materials/pn/h20n12s2 "PN H20N12S2") - [H23N13 Indicative](/materials/pn/h23n13 "PN H23N13") STAS Romania · 1 - [15SiNiCr200 Indicative](/materials/stas/15sinicr200 "STAS 15SiNiCr200") KS South Korea · 1 - [STS309S Indicative](/materials/ks/sts309s "KS STS309S") Every designation on file is listed — no truncation, no “+ n more”. Each one is itself a route that leads back here. ## Chemical composition 8 elements on file · weight % What this alloy is Fe Cr Ni Mn Iron — the balance, never listed by a standard — 60.7 % Cr — 23 % Ni — 13 % Mn — 2 % Traces & impurities · 1.3 % Logarithmic scale, 0.01 % to 100 % — every value here compares directly, decade by decade. | Element | % by weight | |---|---| | C | ≤ 0.15 | | Si | ≤ 1 | | Mn | ≤ 2 | | P | 0.045 | | S | 0.015 | | Cr | 22–24 | | Ni | 12–14 | | N | 0.11 | Carbon Silicon Manganese Phosphorus Sulfur Chromium Nickel 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 | ≤0,15 | — | 0.150 | Max | | N | 0,11 | 0.110 | 0.110 | Exact | | Si | ≤1,00 | — | 1.000 | Max | | P | 0,045 | 0.045 | 0.045 | Exact | | S | 0,015 | 0.015 | 0.015 | Exact | | Cr | 22,0-24,0 | 22.000 | 24.000 | Range | | Mn | ≤2,00 | — | 2.000 | Max | | Ni | 12,0-14,0 | 12.000 | 14.000 | 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 7,9 g/cm³ Exact Weldability weldable with restrictions As published: limited weldability. 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 6 conditions · 36 values By delivery state**no delivery state stated** source `steeljis` | Delivery state | Rm N/mm² | Re N/mm² | A% | HB | HRB | HV | |---|---|---|---|---|---|---| | Plate/Sheet Hot-rolled | 520 | 205 | 40 | — | — | — | | Hot-rolled | — | — | — | 187 | 90 | 200 | By delivery state**Solution annealed** source `steelnumber` | Delivery state | HB | |---|---| | Solution annealed | 192 | By dimension**Quenching 1100 - 1150°C, air** source `splav` | Dimension mm | Rm N/mm² | Re N/mm² | A5% | Z% | |---|---|---|---|---| | Ø 60 | 490 | 295 | 35 | 50 | By heat-treated condition**no delivery state stated** source `splav` | Heat-treated condition | Rm N/mm² | A5% | |---|---|---| | Sheet trick, GOST 7350-77 | 570 | 35 | By heat-treated condition**no delivery state stated** source `splav` | Heat-treated condition | Rm N/mm² | A5% | |---|---|---| | Sheet thin, GOST 5582-75 | 540 | 35 | 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) | |---|---|---|---|---|---| | 20 | 7.82 | 207 | — | — | — | | 100 | 7.79 | — | 14.9 | — | 538 | | 200 | — | — | 15.7 | 17 | — | | 300 | — | — | 16.6 | 19 | — | | 400 | — | — | 17.1 | 21 | — | | 500 | — | — | 17.5 | 23 | — | | 600 | 7.58 | — | 17.8 | 24 | — | | 700 | — | — | 18.2 | 27 | — | | 800 | 7.48 | — | — | 29 | — | | 900 | — | — | — | 31 | — | 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 1.4, a shared category, and a published range for Cr / Ni 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. [X6CrNi23-13 1.4950 Cr 22,0-24,0 · Ni 12,0-15,0 - ΔCr 0.00 - ΔNi 0.50 - 32 designations](/materials/din-en/x6crni23-13 "X6CrNi23-13")[X7CrNiSiNCe21-11 1.4835 Cr 20,0-22,0 · Ni 10,0-12,0 - ΔCr 2.00 - ΔNi 2.00 - 12 designations](/materials/din-en/x7crnisince21-11 "X7CrNiSiNCe21-11")[X12CrNiMoNb20-15 1.4885 Cr 19,0-22,0 · Ni 14,0-16,0 - ΔCr 2.50 - ΔNi 2.00 - 1 designations](/materials/din-en/x12crnimonb20-15 "X12CrNiMoNb20-15") ## 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=4ad5b983-4150-4491-9e47-83a57bc065d4&designation=d2a3abc1-c930-46e1-a365-ab122a500a61 "Inquiry")[**Datasheet as PDF** Print-ready A4 document **Generating …** **Download started** **Try again**](/materials/aisi-sae/mt309.pdf "Datasheet as PDF")