Incoloy DS is a heat-resistant nickel-iron-chromium alloy with a deliberate silicon addition. This datasheet presents the material within the American (ASTM / ASME / UNS) standard system.
A general-purpose heat-resisting material, Incoloy DS combines high nickel and chromium contents with about 2% silicon to give good oxidation and scaling resistance up to about 1100 °C (2000 °F), particularly under cyclic conditions of heating and cooling. The high silicon and chromium contents give it excellent resistance to carburisation — superior to standard alloy 330 — 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, typical values for Incoloy DS.
| Condition | Property | Value |
|---|---|---|
| Annealed | Tensile strength (UTS) | ≥550 MPa (80 ksi) |
| Annealed | 0.2% yield strength | ≥230 MPa (33 ksi) |
| Annealed | Elongation at break | ≥30 % |
| Elevated temperature | High-temperature strength | Good; creep-resistant |
| — | Elastic modulus | 196 GPa |
Confirm against the mill test report. Properties depend on product form and condition; the alloy is used annealed or solution-treated.
| Environment | Performance | Notes |
|---|---|---|
| High-temperature oxidation | Excellent | To about 1100 °C, incl. cyclic |
| Carburisation | Excellent | High Si + Cr; superior to alloy 330 |
| 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 alloy; not hardenable by precipitation. Properties are set by annealing.
Anneal Anneal (solution treat) at approximately 1020–1150 °C (1870–2100 °F) and cool by water quenching or as fast as possible. Annealing is recommended after hot working. The alloy is not strengthened by heat treatment; cold work raises strength.
Good weldability by the conventional processes for austenitic heat-resistant alloys; 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-alloy 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 | ASTM Standard | ASME |
|---|---|---|
| Bar and rod | ASTM B511 | ASME SB-511 |
| Plate, sheet and strip | ASTM B536 | ASME SB-536 |
| Seamless pipe and tube | ASTM B535 / B546 | ASME SB-535 |
| Wire | ASTM B512 | — |
Nickel-iron-chromium heat-resistant alloy with silicon. Incoloy DS.
| Alloy | Ni % | Cr % | Si % | Best Used For |
|---|---|---|---|---|
| Incoloy DS | 37–39 | 17–19 | 1.0–2.0 | High-Cr/Si heat-resistant; carburisation resistance, furnace parts |
| Incoloy 330 | 34–37 | 17–20 | 0.75–1.5 | Standard general-purpose heat-resistant alloy |
| Incoloy 800H | 30–35 | 19–23 | ≤1.0 | Higher-temperature creep service |
| RA330 | 34–37 | 17–20 | 1.0–1.5 | Heat-resistant furnace alloy (330 type) |
| Type 310S | 19–22 | 24–26 | ≤1.5 | High-temperature oxidation resistance |




