X8NiCrSi38-18 is the EN symbol designation for a heat-resistant austenitic nickel-iron-chromium steel with a silicon addition. This datasheet presents the material within the EN symbol designation system.
A general-purpose heat-resisting material, X8NiCrSi38-18 combines high nickel and chromium contents with about 2% silicon to give good oxidation and scaling resistance up to about 1100 °C, particularly under cyclic conditions of heating and cooling. The high silicon and chromium contents give it excellent resistance to carburisation and good resistance to nitrogen-containing atmospheres with low oxygen content. It has a solid-solution composition with small amounts of precipitated titanium nitride and carbide, is not hardenable by heat treatment, and offers good high-temperature strength with excellent workability and weldability. It is supplied in the annealed and solution-treated condition.
Typical applications include industrial heating-furnace components, muffles, retorts, conveyor systems, carburising boxes and baskets, alloy grids, flare tips, and boiler and furnace fixtures.
| Property | Value | Unit |
|---|---|---|
| Density | 7.94 | g/cm³ |
| Melting range | 1350–1400 | °C |
| Elastic modulus | 196 | GPa |
| Coefficient of thermal expansion (20–100 °C) | 15.5 | µm/m·°C |
| Thermal conductivity (20 °C) | 12.0 | W/m·K |
| Specific heat (20 °C) | 460 | J/kg·K |
| Structure | Austenitic (FCC) | — |
| Element | Symbol | Min % | Max % | Role in Alloy |
|---|---|---|---|---|
| Iron | Fe | Balance | — | Base element |
| Nickel | Ni | 37.0 | 39.0 | Austenite stabiliser; carburisation resistance |
| Chromium | Cr | 17.0 | 19.0 | Oxidation / scaling resistance |
| Silicon | Si | 1.00 | 2.00 | Enhances oxidation / carburisation resistance |
| Manganese | Mn | — | 1.50 | Deoxidiser |
| Titanium | Ti | — | 0.60 | Forms nitride / carbide |
| Carbon | C | — | 0.10 | Carbide formation |
Annealed condition, per EN reference data for W.Nr. 1.4862.
| Condition | Property | Value |
|---|---|---|
| Annealed | Tensile strength (Rm) | ≥550 MPa |
| Annealed | 0.2% proof strength (Rp0.2) | ≥230 MPa |
| Annealed | Elongation (A5) | ≥30 % |
| Elevated temperature | High-temperature strength | Good; creep-resistant |
| — | Elastic modulus | 196 GPa |
Values per EN reference data; properties depend on product form and condition. Confirm against the inspection certificate (EN 10204).
| Environment | Performance | Notes |
|---|---|---|
| High-temperature oxidation | Excellent | To about 1100 °C, incl. cyclic |
| Carburisation | Excellent | High Si + Cr |
| Nitriding (low-oxygen N₂ atmospheres) | Very Good | Good resistance |
| Chloride stress-corrosion cracking | Very Good | High nickel content |
| Sulfidation | Moderate | Better under oxidizing than reducing conditions |
The high nickel, chromium and silicon contents give excellent resistance to oxidation and carburisation at high temperature; resistance to sulfidation is better under oxidizing than reducing conditions, as sulfide scale tends to spall.
A solid-solution austenitic steel; not hardenable by precipitation. Properties are set by annealing.
Anneal Anneal (solution treat) at approximately 1020–1150 °C and cool by water quenching or as fast as possible. Annealing is recommended after hot working. The steel is not strengthened by heat treatment; cold work raises strength.
Good weldability by the conventional processes for austenitic heat-resistant steels; neither pre- nor post-weld heat treatment is required. Matching or compatible filler is used.
| Welding Process | Applicability | Filler / Consumable |
|---|---|---|
| GTAW / TIG | Good | Matching / compatible filler |
| GMAW / MIG | Good | Compatible filler |
| SMAW / stick | Good | For heavier sections |
Weld with conventional austenitic practice and clean surfaces; no pre- or post-weld heat treatment is required.
Machining Guidelines
| Parameter | Recommendation |
|---|---|
| Machinability | Requires higher power than mild steel; work-hardens |
| Tooling | Sharp carbide; rigid setups, positive feeds |
| Coolant | Ample coolant |
Forming Processes
| Process | Notes |
|---|---|
| Cold forming | Good; work-hardens, anneal between heavy operations |
| Hot forming | 1150–950 °C; water quench / fast cool, anneal afterward |
| Industry | Typical Components | Key Requirements |
|---|---|---|
| Industrial furnaces | Muffles, retorts, fixtures | Oxidation + carburisation resistance |
| Heat treatment | Carburising boxes, baskets, grids | Carburisation resistance |
| Process / petrochemical | Conveyor systems, flare tips | High-temperature strength |
| Power / boiler | Furnace and boiler fixtures | Oxidation resistance |
| Product Form | DIN / EN Standard | Notes |
|---|---|---|
| Bar, rod and section | EN 10095 · W.Nr. 1.4862 | X8NiCrSi38-18 |
| Plate, sheet and strip | EN 10095 · W.Nr. 1.4862 | — |
| Seamless pipe and tube | DIN 17470 · W.Nr. 1.4862 | — |
| Inspection documents | EN 10204 | — |
Nickel-iron-chromium heat-resistant steel with silicon. W.Nr. 1.4862 (X8NiCrSi38-18).
| EN Symbol | Ni % | Cr % | Si % | Best Used For |
|---|---|---|---|---|
| X8NiCrSi38-18 | 37–39 | 17–19 | 1.0–2.0 | High-Cr/Si heat-resistant steel; carburisation resistance, furnace parts |
| X12NiCrSi35-16 | 34–37 | 15–17 | 1.0–2.0 | Heat-resistant Ni-Cr-Fe-Si alloy (1.4864) |
| X10NiCrAlTi32-21 | 30–35 | 19–23 | ≤1.0 | Higher-temperature creep service (800H) |
| X15CrNiSi25-21 | 19–22 | 24–26 | ≤1.5 | High-temperature oxidation resistance (310S) |
| X25CrMnNiN25-9-7 | 4–6 | 24–26 | ≤1.0 | Heat-resistant austenitic furnace steel |




