Incoloy DS is a high-temperature nickel-iron-chromium alloy known for its excellent resistance to oxidation, carburization, and sulfidation at elevated temperatures. The “DS” designation indicates a grade with controlled silicon content (typically 1.5–2.5 percent) to enhance resistance to high-temperature corrosion, particularly in carbon-rich atmospheres. The alloy is solid-solution strengthened and is not precipitation hardenable.

The nominal chemical composition is: nickel 34.0–37.0 percent, chromium 17.0–19.0 percent, silicon 1.5–2.5 percent, carbon up to 0.15 percent, manganese up to 1.0 percent, and the balance iron.

Key mechanical properties (typical, annealed condition):

● Tensile strength: 550–700 MPa

● Yield strength (0.2% offset): 240–310 MPa

● Elongation: 30–40 percent

● Density: 7.9 g/cm³

Incoloy DS offers outstanding resistance to carburization (carbon absorption) and metal dusting at temperatures up to about 1,100°C (2,000°F). The high silicon content promotes the formation of a protective, adherent oxide layer that resists spalling under thermal cycling. The alloy also provides good oxidation resistance and moderate creep strength. It is readily weldable and has good formability.

Common standards: This alloy is often supplied to proprietary specifications or to ASTM B511 (rod, bar), B536 (plate, sheet, strip). It is similar to UNS N08330 (RA330) but with a higher silicon range. Incoloy DS is sometimes referred to as a variant of Incoloy 330.

Typical applications include:

● Heat treatment equipment: furnace muffles, radiant tubes, retorts, and baskets for carburizing and carbonitriding processes.

● Petrochemical industry: components exposed to carburizing atmospheres, such as cracking furnace tubes and pyrolysis coils.

● Glass manufacturing: lehr rolls and other high-temperature hardware.

● Power generation: superheater supports and hangers.

Comparison with other alloys: Incoloy DS has superior carburization resistance compared to standard Incoloy 800 or 800H due to its higher silicon content. For maximum oxidation resistance without carburization concern, Inconel 601 is a better choice. For higher creep strength at temperature, Incoloy 800HT or Inconel 617 may be selected.

Selection guidance: Choose Incoloy DS for furnace components and other high-temperature equipment operating in strongly carburizing or carbon-rich atmospheres where resistance to carbon penetration and metal dusting is critical. For less severe conditions, standard stainless steel 310 or Incoloy 800 may be sufficient and more economical.