Key takeaways
- What it is: 1.4864 (X12NiCrSi35-16) is a high-nickel (~35%), silicon-bearing austenitic heat-resistant steel — the same alloy family as AISI 330 / UNS N08330 / SUH330.
- What it does best: resists both oxidation and carburization in hot, carbon-bearing atmospheres up to about 1,150°C (2,100°F).
- Why the nickel matters: ~33–37% nickel stabilises the austenite, slows carbon pickup, and resists sigma-phase embrittlement and chloride stress-corrosion cracking.
- Where it is used: furnace internals, retorts, radiant tubes, carburizing-line hardware, kiln and petrochemical high-temperature parts.
- How it is supplied: open-die forgings and seamless rolled rings — bars, discs, blocks, hollow bars and rings — solution annealed, with EN 10204 3.1/3.2 certification.
The short answer
1.4864 — chemical name X12NiCrSi35-16 — is an austenitic heat-resistant material with roughly 35% nickel, 16% chromium and a deliberate slug of silicon. That recipe is unusual: most stainless grades lean on chromium alone, while 1.4864 adds a large nickel reserve and a silicon-rich surface layer. The payoff is resistance to both oxidation and the far more destructive carburization in hot, carbon-bearing atmospheres, up to about 1,150°C. It is the alloy engineers reach for when a part has to live inside a furnace, a retort or a heat-treatment line for years.
Ordinary 304 or 316 stainless will scale and lose its protective film long before 1.4864 is even warmed up. What sets 1.4864 apart is metallurgical stability at temperature: high nickel keeps the structure austenitic and resists carbon pickup, while silicon builds a tenacious oxide barrier that slows further attack.
Why one alloy has seven names
If you have searched for this material you have probably met it under several labels and wondered whether they are the same thing. Broadly, yes. The naming simply reflects the standard doing the talking.
1.4864 and X12NiCrSi35-16 are the European (EN) numeric and chemical names for the wrought heat-resisting steel. The chemical name reads like a formula: X for high-alloy, 12 for ~0.12% carbon, then the leading elements Ni-Cr-Si with their approximate percentages 35-16.
AISI 330 / UNS N08330 is the North American designation, where the grade is usually treated as a nickel-iron-chromium alloy rather than a steel. SUH330 is the Japanese (JIS) equivalent and W.Nr. 1.4886 a closely related number. This alloy family is also sold commercially under proprietary trademarks owned by their respective holders; where such a name appears anywhere on this site it is used only to identify the grade, and never to imply that the trademark owner produced the part. We identify material by its EN, ASTM, UNS or JIS designation and certify to the actual standard.
Composition ranges shift slightly between EN, ASTM and JIS — chromium is often quoted a little higher in the N08330 window. Always state the governing standard on your enquiry and read the mill certificate against it, rather than assuming the grades are numerically identical.
Chemical composition, and what each element buys you
Representative EN-basis composition for X12NiCrSi35-16. Treat these as typical ranges for orientation; the values that govern your order are the ones on the material certificate for the applicable specification.
| Element | Symbol | Typical % | What it does here |
|---|---|---|---|
| Nickel | Ni | 33.0–37.0 | The backbone. Stabilises the austenite phase and slows carbon diffusion, giving the grade its carburization resistance. |
| Chromium | Cr | 15.0–17.0 | Forms the chromium-oxide scale that provides baseline oxidation and corrosion protection. |
| Silicon | Si | 1.0–2.0 | The quiet hero. Builds a silica-rich subscale beneath the chromia layer that sharply improves high-temperature oxidation resistance. |
| Carbon | C | ≤ 0.15 | Contributes to creep strength; kept moderate to limit sensitization. |
| Manganese | Mn | ≤ 2.0 | Deoxidiser and austenite former during melting. |
| Nitrogen | N | ≤ 0.11 | Minor austenite stabiliser and strengthener. |
| Phosphorus | P | ≤ 0.045 | Residual, held low. |
| Sulphur | S | ≤ 0.015 | Residual, held low for cleanliness and forgeability. |
| Iron | Fe | Balance | The remainder of the matrix. |
Ranges are indicative and rounded for readability. Confirm exact limits against EN 10095, ASTM B511/B536 or the standard specified on your drawing.
The takeaway is that 1.4864 spends its alloy budget differently from a grade like 310S. Instead of piling on chromium, it invests in nickel plus silicon — a combination tuned for atmospheres that would carburize a high-chromium steel from the inside out.
The temperature story
Everything about 1.4864 points upward on the thermometer. The scale below places its capabilities against the temperatures where common failures happen.
Oxidation resistance
In hot air, the chromium and silicon build a layered, adherent oxide that resists spalling even under thermal cycling. That adherence matters: a scale that flakes off exposes fresh metal and accelerates loss, so a stable, self-healing film is worth more than a slightly thicker one.
Carburization resistance
This is where 1.4864 separates from the pack. In carbon-rich atmospheres — carburizing furnaces, some petrochemical streams and reformer environments — carbon diffuses into the metal, forms brittle carbides and destroys ductility. The alloy's very high nickel content slashes the rate of carbon uptake, giving parts a far longer working life in exactly the atmospheres that eat ordinary heat-resistant steels.
Physical & mechanical properties at a glance
Typical values in the solution-annealed condition, at room temperature unless noted. Use them for orientation; design must rely on certified data for the exact product form.
| Property | Typical value | Notes |
|---|---|---|
| Density | ~8.0 g/cm³ | Consistent with a high-nickel austenitic matrix. |
| Crystal structure | Austenitic (FCC) | Non-magnetic in the annealed state. |
| Tensile strength (RT) | ~550–620 MPa | Representative; falls with rising temperature. |
| 0.2% proof stress (RT) | ~240–290 MPa | Moderate — chosen for stability, not peak yield. |
| Elongation (RT) | ~30–40% | Good ductility when properly annealed. |
| Max air service temp. | ~1,150°C | Continuous; depends on atmosphere & load. |
| Delivery condition | Solution annealed | Restores ductility and dissolves carbides after forging. |
Values are representative and vary with product form, section size and heat treatment. Always confirm against the mill test certificate.
Corrosion behaviour and long-term stability
High-temperature service is not only about oxidation. Two slower failure modes quietly destroy parts over months, and 1.4864 is designed to resist both.
Sigma-phase embrittlement
Many chromium-rich stainless steels form brittle sigma phase after prolonged mid-temperature exposure, turning a tough part glassy and prone to cracking. The high nickel and moderated chromium of 1.4864 make it markedly more resistant to sigma formation, so components keep their toughness through long service intervals.
Chloride stress-corrosion cracking
Austenitic stainless steels with lower nickel are vulnerable to chloride stress-corrosion cracking. Because susceptibility drops as nickel rises, the ~35% nickel in 1.4864 gives it useful resistance where chlorides and stress meet.
1.4864 is a high-temperature specialist, not a general corrosion alloy. For aggressive acids or sour service, dedicated grades — duplex, super-austenitic or dedicated nickel-base alloys — are the right call. Match the alloy to the dominant threat.
1.4864 vs 310S vs 1.4841
These three heat-resistant grades are often shortlisted together. The difference comes down to how each buys its high-temperature performance.
| Feature | 1.4864 / N08330 | 310S / 1.4845 | 1.4841 / 314 |
|---|---|---|---|
| Nickel | ~33–37% | ~19–22% | ~19–22% |
| Chromium | ~15–17% | ~24–26% | ~24–26% |
| Silicon | ~1–2% | ≤ 1.5% | ~1.5–2.5% |
| Strategy | High Ni + Si | High Cr | High Cr + Si |
| Carburization | Excellent | Good | Good |
| Best when... | Carbon-bearing / cyclic hot atmospheres | Clean oxidising air, cost-sensitive | Oxidising air needing scale adherence |
In plain terms: if your atmosphere is clean and oxidising, high-chromium 310S is often the economical choice. If carbon pickup, thermal cycling or sigma-phase stability is the risk, the extra nickel in 1.4864 usually pays for itself in service life.
Forged forms & typical applications
As open-die forgings and seamless rolled rings, 1.4864 is supplied as bars, discs, blocks, hollow bars, flanges and contoured rings — then machined into the parts below.
Furnace internals
Hearth parts, muffles, baskets, trays and fixtures that live continuously inside heat-treatment furnaces.
Retorts & radiant tubes
Enclosures and tubes exposed to hot, often carbon-bearing atmospheres where carburization would kill lesser grades.
Carburizing equipment
Rollers, rails and support structures inside carburizing and carbonitriding lines.
Petrochemical high-temp
Components in reformers and process furnaces where thermal stability matters more than raw strength.
Kiln & cement hardware
Forged rings and wear parts for rotary kilns and high-temperature material handling.
Thermowells & burner parts
Small precision components that must resist scaling and keep dimensional integrity when hot.
Forging & heat treatment notes
High-nickel austenitic grades reward disciplined hot working. A few points that separate a sound forging from a problem part:
Forging
1.4864 is forged hot, within a controlled temperature window, with enough reduction to close porosity and refine grain flow — a forging ratio comfortably above 3:1 is typical for demanding rotating or pressure parts. The material work-hardens, so tooling and press capacity must account for its resistance to deformation.
Solution annealing
After forging, parts are solution annealed and rapidly cooled to dissolve carbides, homogenise the structure and restore ductility. Skipping or under-doing this step leaves a part that looks right but embrittles early in service.
Verification
For critical duty, forgings are checked by ultrasonic testing for internal soundness, positive material identification to confirm the grade, and mechanical testing — issued with EN 10204 3.1 or third-party co-signed 3.2 certification for full traceability.
How to specify and buy 1.4864 forgings
To get an accurate quote and the right part the first time, put these on your enquiry: state the grade & standard clearly (for example "X12NiCrSi35-16 / 1.4864 to EN 10095" or "N08330 to ASTM B511"); the form & dimensions (bar, disc, block, hollow or rolled ring, with tolerances); the condition (solution annealed unless specified otherwise); the testing & certification you need (UT class, PMI, mechanicals, EN 10204 level); and the service conditions (temperature, atmosphere, loading) so the supplier can confirm 1.4864 is genuinely the best fit.
This guide is the reference material; for available sizes, forms, stock and pricing, use the dedicated product page. You can review specifications and send a drawing there: 1.4864 / X12NiCrSi35-16 forged parts.
Need 1.4864 forgings cut to your drawing?
Jiangsu Liangyi Co., Limited supplies X12NiCrSi35-16 / N08330 open-die forgings and seamless rolled rings — with forging, heat treatment, machining and EN 10204 3.1/3.2 documentation. Send your specification for a free review and quote.
Standards & references
1.4864 / X12NiCrSi35-16 and its equivalents are covered by internationally recognised material and inspection standards. Specify the ones relevant to your order so the mill certificate is measured against the correct requirements.
- EN 10095 Heat-resisting steels and nickel alloys — the European standard defining X12NiCrSi35-16 (1.4864) as an austenitic heat-resistant steel.
- ASTM B511 / B512 / B536 Specifications for the corresponding nickel-iron-chromium alloy N08330 (AISI 330) in bar, billet and plate/sheet forms.
- JIS G4311 (SUH330) Japanese standard for the equivalent heat-resisting steel grade.
- EN 10204 Inspection documents (Type 3.1 and 3.2) governing the material certificates issued with each forging.
- ASTM A388 / ASTM E709 Reference procedures for ultrasonic and magnetic-particle examination of forgings.
These are material and inspection standards that a forging can be produced and tested to — they are not company accreditations. Jiangsu Liangyi Co., Limited holds an ISO 9001:2015 quality-management-system certificate; no other certification is claimed. Material is supplied to the standard named on your order, and each item is accompanied by the corresponding EN 10204 mill test certificate. Always work to the current, in-force revision of the applicable specification.
Frequently asked questions
Is 1.4864 a stainless steel or a nickel alloy?
What is the maximum service temperature?
What grades are equivalent to 1.4864 / X12NiCrSi35-16?
Why is silicon so important in this grade?
Can 1.4864 be welded and machined?
This guide is provided for general engineering orientation. Composition and property figures are representative and rounded; they do not replace the governing standard or the mill test certificate for a specific order. Any third-party grade names or trademarks mentioned belong to their respective owners and are used only to identify the material grade, not to imply any affiliation or endorsement. Verify all values against the applicable specification before design or purchase.