1.4857 is an iron–nickel–chromium alloy designed for petrochemical, chemical and thermal-processing applications. This datasheet presents the material within the European (EN cast / Werkstoff-Nummer) standard system.
Its nickel and chromium contents are higher than those of the high-temperature / 800HT grades, and the ratios of nickel, iron and chromium are balanced to give optimum properties in the 840–1150 °C (1550–2100 °F) range. It is a cost-effective material providing an exceptional level of high-temperature corrosion resistance in oxidation, sulfidation and carburisation environments, together with excellent stress-rupture strength at elevated temperatures.
These characteristics — high resistance to carburisation and cyclic oxidation combined with high creep-rupture strength — make it the material of choice for many severe applications, notably ID-finned pyrolysis tubing in high-severity ethylene furnaces. Like the other 800-series alloys it shows good resistance to chloride stress-corrosion cracking, but can be sensitised by exposure to 540–760 °C; solution annealing restores ductility after long high-temperature exposure.
Values per Special Metals official datasheet, annealed condition.
| Property | Value | Unit |
|---|---|---|
| Density | 7.86 | g/cm³ |
| Melting range | 1365–1400 | °C |
| Young's modulus (20 °C) | 195 | GPa |
| Shear modulus (20 °C) | 73.8 | GPa |
| Poisson's ratio (20 °C) | 0.32 | — |
| Specific heat capacity | 479 | J/kg·K |
| Coefficient of thermal expansion (25–100 °C) | 14.0 | µm/m·°C |
| Magnetic permeability (200 Oe) | 1.001 | Essentially non-magnetic |
| Optimum service range | 840–1150 | °C |
Composition per EN 10295 (W.Nr. 1.4857, GX40NiCrSi35-26).
| Element | Symbol | Min % | Max % | Role in Alloy |
|---|---|---|---|---|
| Iron | Fe | Balance | — | Base element |
| Nickel | Ni | 33.0 | 36.0 | Austenite stability |
| Chromium | Cr | 24.0 | 27.0 | Oxidation resistance |
| Carbon | C | 0.30 | 0.50 | Carbide strengthening (creep) |
| Silicon | Si | 1.0 | 2.5 | Oxidation / carburization resistance |
| Manganese | Mn | — | 2.0 | Deoxidiser |
| Phosphorus | P | — | 0.04 | Residual impurity |
| Sulphur | S | — | 0.03 | Residual impurity |
Nominal: cast Fe-35Ni-25Cr-Si, high carbon (0.30-0.50%). A cast heat-resistant steel (HK/HT family) for furnace and high-temperature components to ~1100 °C; high carbon gives creep strength.
As-cast condition, per EN 10295 for W.Nr. 1.4857 (cast heat-resistant steel).
| Property | Value | Unit |
|---|---|---|
| Tensile strength (Rm) | ≥440 | MPa |
| 0.2% proof strength (Rp0.2) | ≥220 | MPa |
| Elongation at fracture (A) | ≥6 | % |
Values per EN; confirm against the inspection certificate (EN 10204).
| Environment | Performance | Notes |
|---|---|---|
| Carburisation | Outstanding | Key strength; superior to 1.4958 across a range of oxygen potentials |
| Cyclic oxidation | Outstanding | Excellent for thermal-cycling processing service |
| Static oxidation | Excellent | Protective scale to ~1100 °C |
| Sulfidation | Excellent | Outperforms 1.4958 |
| Creep / stress-rupture | Outstanding | Higher than high-temperature / 800HT |
| Chloride stress-corrosion cracking | Good | Like other 800-series alloys |
| Intergranular (sensitised) | Caution | Can sensitise at 540–760 °C; solution anneal to restore |
An austenitic solid-solution alloy; not age-hardenable. Solution annealing is used to develop properties and to restore ductility after high-temperature exposure.
Solution Anneal Temperature: ~1177 °C (2150 °F), e.g. 15 min, water quench Purpose: dissolves precipitates, restores ductility and corrosion resistance, develops grain structure for creep-rupture strength.
Caution — intermediate-temperature exposure: solid-state precipitation between 590–815 °C on long exposure reduces ductility; re-solution-anneal before repair or deformation after such service.
Good weldability, the same as 1.4958 grade. It should be joined using welding products with comparably high creep-rupture strength and high-temperature corrosion resistance.
| Welding Process | Applicability | Filler / Consumable |
|---|---|---|
| GTAW / GMAW | Excellent | Matching cast/Ni-Cr-Fe filler per EN 10295 practice |
| SMAW / stick | Good | Matching electrode |
| Sulfidation-environment service | — | Sulfidation-resistant matching filler |
For cast tube fabrication, use fillers matched to the cast grade and service environment.
Machining: readily machined by standard methods (similar to other 800-series alloys); the alloy work-hardens during machining.
Forming Processes
| Process | Notes |
|---|---|
| Hot forming | 870–1200 °C; heavy forging 1010–1200 °C; avoid 650–870 °C (cracking risk) |
| Cold forming | Readily cold-formed; moderate-to-high work-hardening rate |
| Solution anneal | ~1177 °C to restore structure after heavy cold work |
| Industry | Typical Components | Key Requirements |
|---|---|---|
| Ethylene production | ID-finned pyrolysis (cracker) tubing for high-severity furnaces | Carburisation resistance + creep-rupture strength |
| Petrochemical | Furnace tubing, pigtails, headers, process piping | High-temperature corrosion resistance |
| Chemical processing | Heat exchangers, thermal-processing hardware | Oxidation + sulfidation resistance |
| Thermal processing | Furnace components, radiant tubes | Cyclic-oxidation + carburisation resistance |
| Power / energy | High-temperature structural components | Stress-rupture strength to ~900 °C |
| Product Form | EN Standard | Notes |
|---|---|---|
| Castings (centrifugal / static) | EN 10295 | Heat-resistant steel and nickel-alloy castings |
| Designation | W.Nr. 1.4857 · GX40NiCrSi35-26 | Cast Ni-Cr-Si heat-resistant grade ("35-26" = ~35Ni/26Cr) |
| Cast tube (centrifugal) | EN 10295 | Reformer / pyrolysis furnace tubes |
EN 10295 is the governing European standard for heat-resistant steel castings. Note: this cast grade (1.4857) is the casting counterpart to wrought heat-resistant Fe-Ni-Cr tube alloys; see verification report for the wrought-vs-cast distinction.
| W.Nr. | Ni % | Cr % | Other | Best Used For |
|---|---|---|---|---|
| 1.4857 | 32–37 | 25–29 | C 0.06–0.10 | Ethylene cracker tubing; carburisation + creep to 1150°C |
| 1.4958 | 30–35 | 19–23 | C 0.05–0.10 | High creep 593–980°C |
| 1.4959 | 30–35 | 19–23 | Al+Ti 0.85–1.20 | Highest 800-series creep |
| 2.4816 | ≥72 | 14–17 | Ni-base | Higher Ni; carburisation to 1095°C |
| 1.4886 | 34–37 | 18–20 | Si 1.0–1.5 | Carburisation + thermal shock to 1148°C |




