Incoloy 909 (UNS N19909) is a precipitation-hardenable nickel-iron-cobalt superalloy engineered for a very low and nearly constant coefficient of thermal expansion combined with high strength up to roughly 650°C (1200°F). For parts that demand tight dimensional stability under thermal cycling (gas-turbine components, precision hardware, and rocket/engine parts), Incoloy 909 offers a unique mix of mechanical performance and thermal stability — and when sourced from MWAlloys you can obtain factory prices from China, rapid stock delivery, and custom processing for forgings, bars, or plate to support production timelines and engineering tolerances.

What is Incoloy 909?

Incoloy 909 (UNS N19909) is a nickel-iron-cobalt precipitation-hardened superalloy developed to combine very low coefficient of thermal expansion with high strength after age hardening. It was designed primarily for aerospace and power-generation parts where maintaining tight clearances under thermal cycling yields performance or efficiency benefits (for example, gas-turbine vanes, shrouds and bolts). The alloy achieves its properties through a deliberate balance of Ni, Co, Nb (niobium), Ti (titanium) plus silicon; iron is the balance element. The formulation deliberately avoids chromium to keep thermal expansion low, which trades off oxidation resistance in some environments.

Chemical composition

Below is the standard limiting composition band for Incoloy 909 (reported by the alloy developer). Values are percent by weight.

(Reference: Special Metals technical bulletin — Table 1.)

Metallurgical note: the niobium + titanium additions enable precipitation hardening; silicon improves notch-rupture resistance. Because chromium is intentionally absent or very low, the material emphasizes thermal expansion control over oxidation protection; therefore protective coatings or environmental controls are sometimes required for high-temperature oxidative service.

Physical properties

Practical implication: the density and modulus make Incoloy 909 significantly heavier than aluminium alloys but lighter or similar to other nickel superalloys; designers use its low thermal growth to maintain close running clearances without sacrifice in strength.

Mechanical properties & hardness

Incoloy 909 is usually supplied in solution-treated and age-hardened conditions to achieve peak strength. Because properties vary with exact heat-treatment schedules and product form, the table below reports representative, widely referenced values.

Notes on hardness: published supplier datasheets and cross reference tables show Rockwell C values around the high 30s for typical age-hardened bars or forgings. Hardness will be lower in the annealed/solution-treated condition and increases after the prescribed age schedule (for example: solution 980°C / 1 hr, air cool; age ~720°C / 8 hrs with controlled cool). Always confirm with mill certificates and post-treatment testing for critical parts.

Heat treatment and typical processing

Standard heat treatment (example used for data in developer literature):

• Solution treat: 1800 °F (980 °C) for 1 hour then air cool.

• Age harden: 1325 °F (720 °C) for 8 hours, then furnace cool at ~100 °F (55 °C)/hr to 1150 °F (620 °C) for 8 hours, then air cool.
  These schedules were used for the tables and figures in the Special Metals bulletin; shop processes may be adapted for part geometry and required property balance.

Forming & forging: hot-working window typically lies between 870–1120 °C (1600–2050 °F), with specific forging sequences recommended to optimize recrystallization and grain refinement.

Welding: GTAW (TIG) is commonly used; general recommendations for joint prep and filler choices are available from the producer (Special Metals). Parts often require careful control of heat-input and may need post-weld age cycles to restore properties.

Machining: best done with conventional tooling and reduced feeds for high-strength nickel alloys; rough machining is typically performed in the annealed condition. For production runs, consult tooling guidance for Group D-2 alloys.

Corrosion, oxidation and coatings

Because Incoloy 909 was formulated without chromium to minimize thermal expansion, high-temperature oxidation resistance is lower than chromium-bearing superalloys (for example Inconel 718). In oxidative service at elevated temperatures the alloy often requires protective coatings (MCrAlY or aluminide coatings) or controlled atmospheres to avoid excessive scale. For many turbine internal components, coatings are routine. The alloy does have improved resistance to hydrogen embrittlement relative to many steels and some nickel alloys.

Practical takeaway: when a design requires both low expansion and long life in hot oxidative air, specify appropriate protective surface treatments or consider alternative low-expansion alloys engineered with oxidation resistance tradeoffs in mind (specialist consultation recommended).

Standards, product forms and specifications

Incoloy 909 is available in the usual mill products: billets, bars, forgings, plate, sheet, wire and rod. Common industry specifications and standards encountered for procurement and acceptance include SAE/AMS product specifications for bars/forgings and related AMS numbers for specific forms (e.g., AMS 5892 for bars/forgings has been referenced in supplier catalogs). The alloy is designated UNS N19909. Always request the exact AMS/ASTM/SAE spec number that applies to your form and application when you place a purchase order or request a dry certificate.

How Incoloy 909 compares with Inconel

• Base chemistry: Inconel alloys are typically nickel-chromium based with nickel content often over 50%. Incoloy alloys generally contain substantial iron and typically less nickel. Incoloy 909 is a nickel-iron-cobalt alloy with iron as balance and purposely little or no chromium.

• Thermal expansion: Incoloy 909 was developed for very low and stable thermal expansion; most Inconel alloys have significantly higher coefficients. This makes Incoloy 909 better for stability-critical parts.

• High-temperature oxidation resistance: Inconel alloys with chromium (e.g., 718) resist oxidation better; Incoloy 909 may need coatings in hot-oxidizing atmospheres.

• Mechanical strength: Both families include high strength grades; Incoloy 909 is competitive in strength where thermal expansion control is required.

Design summary: choose Incoloy 909 when dimensional stability over temperature cycles plus high strength are priorities. Choose chromium-bearing Inconel types if oxidation resistance in hot air is primary.

Equivalent materials and substitution notes

Direct "drop-in" equivalents are limited because Incoloy 909’s low CTE is a property set rather than a single mechanical metric. Claimed equivalents sometimes include proprietary alloys or certain grades in other proprietary lines (e.g., Carpenter’s CTX-909 grade), but substitution requires careful comparison of:

• chemical composition (especially Nb/Ti/Ni/Co balance),

• target heat treatment,

• coefficient of thermal expansion over the operating range,

• high-temperature strength and rupture data.

Common substitutes in some designs (only after engineering validation): other low-expansion, precipitation-hardening superalloys such as Incoloy 903 / 907 / certain proprietary grades — but expect differences in oxidation or manufacturability. Consult the original spec sheet and supplier data for qualification testing before substitution.

Size and weight: practical chart and calculation

Use the density (8.19 g/cm³) for weight calculations. Two quick rules:

• Weight (kg) of a round bar = Volume × Density. Volume = π × (D/2)² × L (D in m, L in m).

• Simpler engineering chart (common sizes):

(Compute mass = volume × 8.19 g/cm³ → 8,190 kg/m³.) These quick checks help when preparing quotes or freight planning. Always round up for machining allowance and clamp/fixture material needs.

Indicative global price table — 2025

Important: superalloy prices vary strongly with form (bar, plate, tube), order quantity, market metal surcharges, and regional freight & duty. The table below gives indicative spot price ranges (USD per kilogram) in 2025 for nickel-base superalloys and comparable Incoloy grades; Incoloy 909 is a niche, low-volume specialty alloy so expect premiums relative to more common Incoloy 800/825. Use these figures only for budgeting; request firm quotations for procurement.

Why a range: published online price lists show Inconel/Incoloy family prices widely scattered because of alloying element surcharges and market cycles; Incoloy 909, being produced to specific UNS/AMS standards, often sits in the specialist premium tier. For firm procurement planning ask MWAlloys for a mill quote with lead time, MOQ, and certificate of conformity.

Typical applications and use cases

• Gas-turbine components: vanes, casings, shrouds and bolts where stable clearances improve thermodynamic efficiency.

• Aerospace hardware: springs, high-strength fasteners and thrust-chamber components.

• Precision instrumentation and gauge blocks: where dimensional drift with temperature is unacceptable.

• Rocket/space and ordnance: select parts needing both strength and low thermal expansion.

Procurement & why choose MWAlloys

MWAlloys supplies Incoloy 909 from our Chinese mills and factory partners with the following advantages for global buyers:

• 100% factory pricing — our purchasing relationships in China allow quotes close to mill level for many common forms (bars, billets, forgings).

• Fast stock delivery — we hold limited inventory for high-demand sizes and can arrange priority processing and export documentation.

• Technical support — MWAlloys engineers assist with heat-treatment schedules, qualification testing, and specification checks (AMS/UNS/ASME).

• Traceability — full mill certificates (chemical and mechanical) and NDT/certification packages supplied upon request.

FAQs

1. Is Incoloy 909 weldable?
   Yes; gas-tungsten-arc welding (GTAW) is commonly used. Weld procedures must control heat input and may require post-weld age cycles to restore targeted strength; consult mill guidance.

2. Can Incoloy 909 be used in hot air without coating?
   For short life or low oxidation exposure it can, but in high-temperature oxidizing service protective coatings are usual because chromium is limited in the alloy.

3. What is the typical heat treatment?
   Solution ~980 °C (1800 °F)/1 hr (air cool) then age ~720 °C (1325 °F)/8 hr with controlled cooling; adapt for part size and qualification tests.

4. How does Incoloy 909’s thermal expansion compare to Inconel 718?
   Incoloy 909 has roughly half the linear thermal expansion of alloys with similar strength (e.g., many Inconel grades) over room temperature → Curie region, which is why it is chosen for dimensionally critical components.

5. What certifications are available?
   Typical certifications include UNS designation (N19909), AMS numbers for product forms, and supplier mill-certs (chemical & mechanical). Ensure your P.O. lists the required AMS/ASTM/SAE spec.

6. Are there machining tips?
   Machine in annealed condition for roughing, use carbide tooling and conservative feeds for finishing; follow Group D-2 tooling guidance from tooling suppliers.

7. Is Incoloy 909 magnetic?
   Incoloy 909 is ferromagnetic below its Curie temperature (~400–455 °C) and becomes paramagnetic above that; this change also influences the thermal expansion curve.

8. Typical lead time from stock?
   If MWAlloys holds your size in inventory: days to a couple of weeks; custom forgings or AMS-qualified items often require longer lead times — request firm ETA with quotation. (Contact MWAlloys sales for exact timing.)

9. Can Incoloy 909 be age-overstressed for creep life?
   Age hardening yields high strength up to ~650 °C; beyond that age hardening effectiveness declines and long-term exposure requires verification with rupture/creep tests.

10. Which documents should I request from supplier?
    Mill chemical analysis (raw material), heat-treatment record, mechanical test report (tensile/RT/HT if required), and applicable AMS/ASTM conformity certificates. For aerospace work, request full traceability and non-conformance procedures.