Alloy 825,Incoloy 825 Strip,UNS N08825

Alloy 825,Incoloy 825 Wire,UNS N08825

Alloy 825 (Incoloy 825 Wire, UNS N08825) - Introduction with Composition, Properties, Applications and Product Form

Alloy 825, commercially known as Incoloy 825 and designated by UNS N08825, is a nickel-iron-chromium superalloy engineered for exceptional all-around corrosion resistance—combining resistance to oxidizing acids, reducing acids, and chloride-induced pitting/crevice corrosion. Unlike specialized corrosion alloys, it balances robust chemical resistance with good mechanical strength and fabricability, making it a versatile choice for chemical processing, oil & gas, marine, and nuclear 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 825 Wire, in particular, stands out for its uniform corrosion resistance and weldability, making it ideal for welding filler metal, spring manufacturing, and precision components in harsh chemical environments. 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 825 (Incoloy 825, UNS N08825) is the foundation of its broad-spectrum corrosion resistance and mechanical performance. The typical composition (by weight) is as follows:

Nickel (Ni): 38-46% (the primary matrix element, providing resistance to chloride-induced stress corrosion cracking (SCC) and serving as a base for alloying elements; enhances low-temperature toughness)

Iron (Fe): 22-30% (balances the alloy’s density and cost; improves fabricability for rolling, forging, and wire drawing—critical for producing thin forms like foil and strip)

Chromium (Cr): 19-23% (forms a dense, protective chromium oxide layer, ensuring resistance to oxidation, sulfidation, and oxidizing acids (e.g., nitric acid, chromic acid))

Molybdenum (Mo): 2.5-3.5% (boosts resistance to reducing acids (e.g., hydrochloric acid, sulfuric acid) and chloride-induced pitting/crevice corrosion by inhibiting localized attack)

Copper (Cu): 1.5-3.0% (enhances resistance to reducing acids—especially sulfuric and phosphoric acid—and improves performance in acidic mine drainage and chemical leaching environments)

Titanium (Ti): 0.6-1.2% (stabilizes the alloy by forming carbides, preventing chromium depletion at grain boundaries (a common cause of intergranular corrosion); also contributes minor precipitation strengthening)

Carbon (C): ≤ 0.05% (minimized to reduce carbide formation, which could compromise corrosion resistance in sensitive environments)

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

Manganese (Mn): ≤ 1.0% (enhances hot workability, reducing cracking during forging and rolling of thick plates and bars)

Phosphorus (P): ≤ 0.03% (strictly limited to avoid grain boundary embrittlement and reduce the risk of SCC)

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

Aluminum (Al): ≤ 0.2% (trace amounts aid in deoxidation without compromising corrosion resistance or fabricability)

This engineered blend—combining nickel-chromium for oxidation resistance, molybdenum for reducing acid resistance, and copper for acid-specific protection—delivers Alloy 825’s signature "one-alloy-fits-many" corrosion performance.

Key Properties

Alloy 825 (Incoloy 825 Wire, UNS N08825) and its various forms exhibit exceptional properties tailored for corrosive, moderate-temperature environments:

Mechanical Properties (Annealed Condition)

Tensile Strength: 550-700 MPa (79,800-101,500 psi) at room temperature; retains ~400 MPa (58,000 psi) at 400°C (752°F)

Yield Strength (0.2% offset): 240-345 MPa (34,800-50,000 psi) at room temperature; retains ~200 MPa (29,000 psi) at 400°C (752°F)

Elongation (in 50 mm): 30-45% (excellent ductility for cold forming—e.g., bending wire into springs, shaping tube into chemical process lines, deep drawing sheet into tanks)

Reduction of Area: 50-65% (superior toughness, resisting fracture under mechanical stress and thermal cycling)

Hardness: 150-200 HB (Brinell hardness) at room temperature; maintains ~130 HB at 400°C (752°F)

Corrosion Resistance (Core Advantage)

Oxidizing Environments: Resists nitric acid (up to 65% concentration at room temperature), chromic acid, and high-temperature air (oxidation resistance up to 815°C/1500°F) — suitable for chemical reactors and furnace components.

Reducing Environments: Withstands hydrochloric acid (dilute concentrations up to 40°C/104°F), sulfuric acid (dilute to moderate concentrations), and phosphoric acid — ideal for acid processing plants.

Chloride Resistance: Exceptional resistance to pitting and crevice corrosion in seawater, brines, and chloride-rich process streams (passes 6% ferric chloride pitting test at 40°C/104°F) — critical for marine and offshore applications.

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

Other Environments: Resists acidic mine drainage, chemical leaching solutions, and industrial steam — versatile for mining and power generation.

Physical Properties

Density: 8.14 g/cm³ (0.294 lb/in³) (lower than pure nickel alloys, reducing weight in structural applications like offshore platforms)

Thermal Conductivity: 15.1 W/(m·K) at 20°C (68°F); increases to 23.0 W/(m·K) at 400°C (752°F) (efficient heat transfer for heat exchanger components)

Coefficient of Thermal Expansion: 13.7 μm/(m·K) (20-300°C/68-572°F); 15.5 μm/(m·K) (20-600°C/68-1112°F) (controlled expansion to minimize thermal stress in assembled systems like chemical process piping)

Modulus of Elasticity: 206 GPa (29,900 ksi) at room temperature; decreases to ~180 GPa (26,100 ksi) at 600°C (1112°F)

Melting Point: 1370-1400°C (2498-2552°F)

High-Temperature Properties

Continuous Service Temperature: Up to 540°C (1000°F) (optimal for corrosion resistance; short-term exposure up to 815°C/1500°F for oxidation-only environments)

Creep Resistance: Moderate creep performance—1000-hour creep rupture strength of ~80 MPa (11,600 psi) at 500°C (932°F) (suitable for moderate-temperature process equipment)

Product Forms

Alloy 825 (Incoloy 825, UNS N08825) is manufactured in a diverse range of forms to accommodate specialized corrosive applications:

Bar: Round bar (diameters 6-200 mm) and Flat bar (thickness 5-100 mm, width 20-500 mm) — ideal for machining into chemical pump shafts, valve bodies, and high-strength fasteners for offshore equipment.

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 825 Wire (diameters 0.3-6 mm) — serves as welding filler metal (TIG/MIG) for joining 825 components, as precision springs in marine instruments, and as sensor wires in chemical process lines.

Rods: Solid cylindrical rods (diameters 2-50 mm) — used for GTAW filler metal and manufacturing small components like instrument probes and valve stems in acid plants.

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

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

Plate and Sheet: Plate (thickness 3-50 mm) and Sheet (thickness 0.2-3 mm) — fabricated into chemical storage tanks, reactor vessels, and offshore platform structural panels.

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 machinery.

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

Applications

The exceptional corrosion resistance and balanced mechanical properties of Alloy 825 (Incoloy 825 Wire, UNS N08825) make it a staple in industries facing aggressive chemical environments:

Chemical Processing

Acid Production & Handling: Storage tanks (plate/sheet), transfer pipes (tube/pipe), and pump impellers (bar/forging stock) for sulfuric, hydrochloric, and phosphoric acid plants — resists acid degradation and product contamination.

Pharmaceutical & Food Processing: Mixers, reactors, and packaging foil (foil/sheet) — corrosion resistance prevents metal leaching into sensitive products.

Chemical Leaching: Equipment for metal extraction (e.g., copper leaching with sulfuric acid) — withstands acidic leach solutions and abrasive slurries.

Oil & Gas (Offshore & Onshore)

Offshore Platforms: Wellhead components (bar/forging stock), subsea pipelines (tube/pipe), and structural panels (plate) — resists seawater corrosion and sour gas (H₂S) attack.

Downhole Equipment: Tubing and casing for high-salinity, high-H₂S wells (tube) — meets NACE MR0175 standards for sour service.

Refineries: Crude oil distillation units and sour water strippers (plate/tube) — resists corrosion from sulfur-containing hydrocarbons.

Marine & Shipbuilding

Ship Systems: Seawater cooling lines (tube), propeller shafts (bar), and hull components (plate) — withstands seawater corrosion and biofouling.

Desalination Plants: Reverse osmosis (RO) system membranes and brine handling pipes (tube/pipe) — resists concentrated chloride solutions.

Power Generation

Nuclear Power: Secondary coolant system components (tube/plate) — resists radiation-induced corrosion and high-temperature water.

Waste-to-Energy Plants: Flue gas desulfurization (FGD) systems (plate/tube) — resists sulfuric acid byproducts from flue gas treatment.

Mining & Metallurgy

Acidic Mine Drainage: Collection tanks and transport pipes (plate/tube) — resists low-pH mine runoff and heavy metal contaminants.

Metal Processing: Heat treatment fixtures (forging stock/bar) and molten metal handling parts — resists corrosive fluxes and high-temperature air.

Specialized Applications by Form

Wire: Welding filler metal for chemical plant components; precision springs in marine instruments.

Tube/Pipe: Chemical process lines and offshore brine transport pipes.

Plate/Sheet: Acid storage tanks and pharmaceutical reactor vessels.

Forging Stock: Large pump casings and wellhead valves for oil & gas.

In summary, Alloy 825 (Incoloy 825 Wire, UNS N08825) — available in forms from Bar and Wire to Plate and Forging Stock — sets a benchmark for versatile corrosion resistance. Its ability to withstand oxidizing, reducing, and chloride environments, combined with diverse product forms, makes it an irreplaceable material in chemical processing, oil & gas, marine, and beyond—where reliability in harsh chemical conditions is non-negotiable.

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 959 gallon liquid totes Special package is available on request.