Alloy 925,Incoloy 925 Wire,UNS N09925

Alloy 925,Incoloy 925 Wire,UNS N09925

Alloy 925 (Incoloy 925 Wire, UNS N09925) - Introduction with Composition, Properties, Applications and Product Forms

Alloy 925, commercially known as Incoloy 925 and designated by UNS N09925, is a precipitation-hardening nickel-iron-chromium superalloy renowned for its exceptional combination of corrosion resistance, high mechanical strength, and fabricability. Engineered to thrive in harsh environments—including sour gas, seawater, and acidic media—this alloy bridges the gap between high-strength steels and corrosion-resistant nickel alloys, making it a critical material in oil & gas, aerospace, and marine industries. It is available in a comprehensive range of forms to meet diverse industrial needs, including Bar (Round bar, Flat bar), Ribbon, Wire, Rods, Tube, Pipe, Foil, Plate, Sheet, Strip, and Forging Stock. Incoloy 925 Wire, in particular, stands out for its uniform strength and corrosion resistance, making it ideal for welding, spring manufacturing, and precision components in offshore and chemical applications. Below is a detailed overview of its chemical composition, key properties, practical applications, and available product forms.

Chemical Composition

The precisely balanced chemical composition of Alloy 925 (Incoloy 925, UNS N09925) is the foundation of its dual 优势: corrosion resistance and precipitation-hardened strength. The typical composition (by weight) is as follows:

Nickel (Ni): 42-46% (the primary matrix element, providing corrosion resistance against chloride and sour gas environments; also enables precipitation of strengthening phases)

Iron (Fe): 22-26% (balances the alloy’s cost and density while maintaining corrosion resistance; enhances fabricability for forming into wire, tube, and sheet)

Chromium (Cr): 19-21% (forms a dense, protective chromium oxide layer, ensuring resistance to oxidation, sulfidation, and general corrosion in acidic media)

Molybdenum (Mo): 2.5-3.5% (boosts resistance to pitting and crevice corrosion in chloride-rich environments—e.g., seawater, brines—and enhances high-temperature strength)

Copper (Cu): 1.5-2.5% (improves resistance to reducing acids like sulfuric acid and aids in precipitation hardening to enhance strength)

Titanium (Ti): 1.9-2.4% (the key precipitation-hardening element—forms gamma-prime (γ’) intermetallic precipitates during aging, significantly increasing strength)

Aluminum (Al): 0.1-0.5% (works with titanium to refine gamma-prime precipitates, further enhancing strength without compromising ductility)

Carbon (C): ≤ 0.03% (minimized to prevent carbide precipitation at grain boundaries, which could reduce corrosion resistance and cause embrittlement)

Silicon (Si): ≤ 0.5% (aids in deoxidation during manufacturing and supports oxide layer formation for oxidation resistance)

Manganese (Mn): ≤ 0.5% (enhances hot workability, enabling fabrication into thin forms like wire and foil)

Phosphorus (P): ≤ 0.015% (strictly limited to avoid grain boundary embrittlement and reduce stress corrosion cracking risk)

Sulfur (S): ≤ 0.01% (minimized to ensure good ductility and resistance to stress corrosion cracking in harsh environments)

This engineered blend—combining nickel-chromium-molybdenum for corrosion resistance and titanium-aluminum for strength—delivers Alloy 925’s unique balance of performance.

Key Properties

Alloy 925 (Incoloy 925 Wire, UNS N09925) and its various forms exhibit exceptional properties that make them indispensable in corrosive, high-stress environments:

Mechanical Properties (Aged Condition, 720°C/1328°F for 8 hours)

Tensile Strength: 1034-1241 MPa (150,000-180,000 psi) at room temperature; retains ~758 MPa (110,000 psi) at 315°C (600°F)

Yield Strength (0.2% offset): 896-1034 MPa (130,000-150,000 psi) at room temperature; retains ~689 MPa (100,000 psi) at 315°C (600°F)

Elongation (in 50 mm): 15-25% (excellent ductility for cold forming—e.g., bending wire into springs, shaping tube into complex bends)

Reduction of Area: 30-40% (superior toughness, resisting fracture under mechanical stress and thermal cycling)

Hardness: 32-38 HRC (Rockwell hardness) at room temperature; maintains ~28 HRC at 315°C (600°F)

Corrosion Resistance

General Corrosion: Excellent resistance to sour gas (H₂S-rich) environments, seawater, brines, and acids (sulfuric, phosphoric, acetic). Outperforms 316 stainless steel and even some nickel alloys in chloride and sour conditions.

Pitting & Crevice Corrosion: Resists pitting in 3.5% NaCl solution (seawater simulant) at temperatures up to 60°C (140°F) and crevice corrosion in harsh brines—critical for offshore and marine applications.

Stress Corrosion Cracking (SCC): Highly resistant to SCC in sour gas (H₂S) and chloride environments, meeting NACE MR0175/ISO 15156 standards for oilfield applications.

Oxidation Resistance: Forms a stable chromium oxide layer, resisting scaling in air at temperatures up to 815°C (1500°F) for extended periods.

Physical Properties

Density: 7.8 g/cm³ (0.282 lb/in³) (lower than pure nickel alloys, reducing weight in structural applications)

Thermal Conductivity: 13.8 W/(m·K) at 20°C (68°F); increases to 20.9 W/(m·K) at 500°C (932°F) (efficient heat transfer for heat exchanger components)

Coefficient of Thermal Expansion: 12.8 μm/(m·K) (20-100°C/68-212°F); 15.1 μm/(m·K) (20-500°C/68-932°F) (controlled expansion to minimize thermal stress in assembled systems like wellhead equipment)

Modulus of Elasticity: 200 GPa (29,000 ksi) at room temperature; decreases to ~180 GPa (26,100 ksi) at 500°C (932°F)

Melting Point: 1350-1400°C (2462-2552°F)

High-Temperature Properties

Continuous Service Temperature: Up to 540°C (1000°F) (maintains strength and corrosion resistance; for short-term exposure, can withstand up to 760°C/1400°F)

Creep Resistance: Good creep performance at moderate temperatures—1000-hour creep rupture strength of ~241 MPa (35,000 psi) at 427°C (800°F)

Product Forms

Alloy 925 (Incoloy 925, UNS N09925) is manufactured in a diverse range of forms to accommodate specialized corrosive and high-stress applications:

Bar: Round bar (diameters 6-200 mm) and Flat bar (thickness 5-100 mm, width 20-500 mm) — ideal for machining into wellhead components, valve stems, and high-strength fasteners for offshore oil & gas.

Ribbon: Thin, flat strips (thickness 0.07-0.8 mm, width 3-80 mm) — used in thermal spray coatings for corrosion protection on steel substrates and flexible seals for chemical reactors.

Wire: Incoloy 925 Wire (diameters 0.3-6 mm) — serves as welding filler metal (TIG/MIG) for joining 925 components, as precision springs in marine environments, and as sensor wires in sour gas wells.

Rods: Solid cylindrical rods (diameters 2-50 mm) — used for GTAW filler metal and manufacturing small components like pump shafts and instrument probes.

Tube and Pipe: Seamless tube (outer diameter 4-150 mm, wall thickness 0.5-10 mm) and pipe (NPS ½-12) — critical for downhole tubing, offshore brine transport, and chemical process lines.

Foil: Ultra-thin sheets (thickness 0.012-0.1 mm) — used as corrosion-resistant liners for electronic components and thin gaskets in precision instruments.

Plate and Sheet: Plate (thickness 3-50 mm) and Sheet (thickness 0.2-3 mm) — fabricated into offshore platform structural parts, heat exchanger plates, and chemical storage tank liners.

Strip: Narrow, flat strips (thickness 0.07-2 mm, width 2-50 mm) — used for precision components like heat exchanger fins, electrical contacts, and seal rings in corrosive environments.

Forging Stock: Billets and ingots (sizes up to 500×500 mm) — hot-forged into complex shapes (e.g., pump casings, turbine disks) requiring high strength and corrosion resistance.

Applications

The exceptional strength-corrosion balance of Alloy 925 (Incoloy 925 Wire, UNS N09925) makes it a staple in industries requiring both durability and resistance to harsh environments:

Oil & Gas (Offshore & Onshore)

Downhole Equipment: Tubing, casing, and wellhead components (bar/tube/forging stock) — resists sour gas (H₂S) and brine corrosion in high-pressure wells, meeting NACE MR0175 standards.

Offshore Platforms: Structural parts (plate/sheet), fasteners (bar), and fluid transport pipes (tube) — withstands seawater corrosion and cyclic stress from waves and wind.

Subsea Systems: Manifolds and connectors (forging stock/tube) — maintains integrity in deep-sea, high-chloride environments.

Aerospace & Defense

Aircraft Components: High-strength fasteners (bar/wire) and engine parts (forging stock) — resists corrosion from jet fuel and atmospheric moisture while withstanding mechanical stress.

Missile & Space Systems: Precision springs (wire) and structural components (sheet) — balances strength and corrosion resistance for harsh operational conditions.

Marine & Shipbuilding

Ship Propulsion Systems: Shafts and bearings (bar/forging stock) — resists seawater corrosion and wear.

Desalination Plants: Brine handling pipes (tube) and heat exchanger plates (sheet) — withstands concentrated chloride solutions.

Chemical Processing

Acid Handling Equipment: Pumps, valves, and tanks (bar/plate/tube) — resists sulfuric and phosphoric acid corrosion.

Pharmaceutical Manufacturing: Stainless steel-lined vessels (foil/sheet) — prevents product contamination from metal leaching.

Power Generation

Waste-to-Energy Plants: Flue gas treatment components (plate) — resists corrosive byproducts like sulfuric acid.

Geothermal Power: Wellhead tubing (tube) — withstands high-temperature, high-salinity geothermal fluids.

Specialized Applications by Form

Wire: Welding filler metal for oilfield components; precision springs for marine instruments.

Tube/Pipe: Downhole tubing for sour gas wells; brine transport lines in desalination plants.

Bar/Forging Stock: Wellhead valves and pump casings for offshore oil & gas.

Plate/Sheet: Offshore platform structural parts and chemical storage tank liners.

In summary, Alloy 925 (Incoloy 925 Wire, UNS N09925) — available in forms from Bar and Wire to Plate and Forging Stock — delivers an unmatched balance of high strength and corrosion resistance. Its diverse product forms enable tailored solutions across oil & gas, aerospace, marine, and chemical sectors, establishing it as a critical material in applications where both durability and environmental resistance are essential.

Packing of Standard Packing: 

Typical bulk packaging includes palletized plastic 5 gallon/25 kg. pails, fiber and steel drums to 1 ton super sacks in full container (FCL) or truck load (T/L) quantities. Research and sample quantities and hygroscopic, oxidizing or other air sensitive materials may be packaged under argon or vacuum. Solutions are packaged in polypropylene, plastic or glass jars up to palletized 1034 gallon liquid totes Special package is available on request.