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Incoloy 825/UNS N08825/W.Nr. 2.4858/Alloy 825 bar

Incoloy 825 bar, designated as UNS N08825, material number W.Nr. 2.4858, and commonly referred to as Alloy 825, is a nickel-iron-chromium alloy with a…

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Incoloy 825 bar, designated as UNS N08825, material number W.Nr. 2.4858, and commonly referred to as Alloy 825, is a nickel-iron-chromium alloy with additions of molybdenum and copper, specifically engineered for excellent corrosion resistance in a wide range of aggressive environments, including sulfuric and phosphoric acids, and seawater. This bar stock form is a versatile and widely used material for machining components such as pump shafts, valve stems, fasteners, and heat exchanger parts in chemical processing, oil and gas, marine, and pollution control industries.

Table of Contents Hide

1 Introduction to Incoloy 825 (Alloy 825)

2 Chemical Composition of Incoloy 825 Bar

3 Mechanical Properties of Incoloy 825 Bar

4 Physical Properties of Incoloy 825 Bar

5 Standard Specifications, Bar Forms, and Available Sizes

6 Primary Applications of Incoloy 825 Bar Stock

7 Corrosion Resistance Overview

8 Machining and Fabrication of Incoloy 825 Bar

9 Welding of Incoloy 825 Bar

10 Reference Pricing and Key Purchasing Factors

Incoloy 825

Introduction to Incoloy 825 (Alloy 825)

Incoloy 825 is a titanium-stabilized austenitic alloy that combines the corrosion resistance of nickel with the strength and cost-effectiveness of iron. Its balanced composition provides strong resistance to reducing acids, pitting and crevice corrosion in chloride solutions, and stress corrosion cracking. The alloy is also known for its good fabricability and weldability. The bar stock is an industry standard for components exposed to corrosive process streams, sour gas, and seawater.

Chemical Composition of Incoloy 825 Bar

The corrosion resistance of Incoloy 825 bar stems from its well-balanced chemistry with stabilizing elements. Supplied by Shanghai NC Metal Materials Co., Ltd., the bar stock conforms to international standards ensuring reliable performance.

Element	Percentage (%) – Typical Range	Primary Function in the Alloy
Nickel (Ni)	38.0 – 46.0	Base element for corrosion resistance; stabilizes the austenitic structure and provides resistance to stress corrosion cracking and reducing environments.
Chromium (Cr)	19.5 – 23.5	Provides resistance to oxidizing media (e.g., nitric acid, oxidizing salts) and high-temperature oxidation/sulfidation.
Iron (Fe)	Balance (≥ 22.0)	Provides the fundamental matrix, contributing to strength and cost structure.
Molybdenum (Mo)	2.5 – 3.5	Enhances resistance to reducing acids (sulfuric, phosphoric) and provides resistance to pitting and crevice corrosion in chloride solutions.
Copper (Cu)	1.5 – 3.0	Improves resistance to sulfuric acid and other reducing acids.
Titanium (Ti)	0.6 – 1.2	Added as a stabilizer to prevent sensitization (chromium carbide precipitation) during welding, preserving corrosion resistance.
Manganese (Mn)	1.0 max	Residual element, deoxidizer.
Silicon (Si)	0.5 max	Residual element.
Carbon (C)	0.05 max	Kept low to minimize carbide precipitation and ensure good weldability and corrosion resistance.
Sulfur (S)	0.03 max	Impurity control.

Mechanical Properties of Incoloy 825 Bar

Incoloy 825 bar offers a good combination of strength and ductility, suitable for structural components in corrosive environments. It is supplied in the solution-annealed condition.

Mechanical Property	Typical Value at Room Temperature (Annealed)	ASTM B425 (UNS N08825) Minimum Requirement	Key Characteristic
Tensile Strength	586 – 689 MPa (85 – 100 ksi)	≥ 586 MPa (85 ksi)	Adequate strength for pressure-containing parts.
Yield Strength (0.2% Offset)	241 – 345 MPa (35 – 50 ksi)	≥ 241 MPa (35 ksi)	–
Elongation in 2 inches (50mm)	≥ 30%	≥ 30%	Good ductility for forming and fabrication.
Hardness (Rockwell B)	≤ 100 HRB	–	–

Physical Properties of Incoloy 825 Bar

The physical properties of Alloy 825 bar are standard for nickel-iron-chromium alloys and are used in equipment design.

Physical Property	Value at Room Temperature (20°C / 68°F)	Notes / Condition
Density	8.14 g/cm³ (0.294 lb/in³)	–
Melting Range	1370 – 1400°C (2500 – 2550°F)	–
Specific Heat	440 J/kg·°C (0.105 BTU/lb·°F)	At 100°C
Thermal Conductivity	11.1 W/m·K (77.0 BTU·in/hr·ft²·°F)	At 100°C
Mean Coefficient of Thermal Expansion	14.0 μm/m·°C (7.8 μin/in·°F)	20-100°C (68-212°F)
Electrical Resistivity	1.12 μΩ·m (44.1 μΩ·in)	At 20°C
Modulus of Elasticity (Tensile)	196 GPa (28.4 x 10^6 psi)	At 20°C

Standard Specifications, Bar Forms, and Available Sizes

Shanghai NC Metal Materials Co., Ltd. supplies Incoloy 825 bar in a comprehensive range of forms for various industrial applications.

Product Form	Standard Size Range	Key Standard Specifications	Common Supply Conditions
Round Bar (Hot Rolled/Forged)	10mm (0.4″) to 300mm (12″) Diameter	ASTM B425 (UNS N08825), ASME SB-425, NACE MR0175/ISO 15156, DIN 17742 (W.Nr. 2.4858)	Solution Annealed (typically 930-980°C water quench)
Hexagonal Bar	10mm to 80mm Across Flats	ASTM B425, DIN 17742	Solution Annealed
Square Bar	10mm to 80mm Width	ASTM B425	Solution Annealed
Cold Finished Bar (Drawn/Ground)	5mm to 150mm Diameter	ASTM B425 (cold drawn)	Solution Annealed, Cold Drawn & Stress-Relieved
Forging Billet	150mm to 400mm Diameter	ASTM B564 (Forgings), Customer specs	As-Forged, Solution Annealed

Primary Applications of Incoloy 825 Bar Stock

Machined components from Incoloy 825 bar are used in a wide array of corrosive services: Chemical Processing: Reactor vessels, heat exchangers, pump shafts, and valves for sulfuric and phosphoric acid production, pickling operations, and handling of acid chlorides. Oil and Gas: Downhole tubing, piping, and components for sour service (H2S/CO2/chlorides) when qualified to NACE standards. Marine and Offshore: Seawater cooling system components, propeller shafts, and fasteners. Pollution Control: Scrubbers, ducting, and stack liners in flue gas desulfurization (FGD) systems. Nuclear Fuel Reprocessing: Equipment for handling spent nuclear fuel in nitric acid solutions.

Corrosion Resistance Overview

Incoloy 825 offers versatile corrosion resistance. It provides excellent resistance to sulfuric acid over a broad concentration and temperature range, especially with its copper content. It is highly resistant to phosphoric acid and many organic acids. The alloy shows good resistance to pitting and crevice corrosion in chloride solutions, though not as high as the 6% molybdenum super-austenitics. Its titanium stabilization makes it highly resistant to intergranular attack after welding or high-temperature exposure. It also resists stress corrosion cracking in chloride and caustic environments.

Machining and Fabrication of Incoloy 825 Bar

Incoloy 825 bar is readily machinable using techniques for austenitic stainless steels and nickel alloys. It work-hardens, so recommended practices include: using rigid setups and sharp carbide tools; moderate cutting speeds; consistent, positive feed rates; and ample coolant. Its machinability rating is better than that of many high-nickel alloys, making it a preferred choice for complex machined components in corrosive service.

Welding of Incoloy 825 Bar

Alloy 825 is considered highly weldable. It can be welded using common processes such as Gas Tungsten Arc Welding (GTAW/TIG), Shielded Metal Arc Welding (SMAW/Stick), and Gas Metal Arc Welding (GMAW/MIG). Matching filler metals (e.g., ERNiCrMo-3) or over-alloyed fillers are recommended. Due to its titanium stabilization, it is resistant to sensitization in the weld heat-affected zone. Post-weld heat treatment is not typically required for corrosion resistance in most applications.

Reference Pricing and Key Purchasing Factors

The price of Incoloy 825 bar from Shanghai NC Metal Materials Co., Ltd. is influenced by its nickel content and its status as a widely used, versatile corrosion-resistant alloy.

Pricing Factor	Impact on Reference Price	Procurement Guidance
Nickel Content	The primary cost driver is the nickel content (~42%). Fluctuations in the nickel market directly affect the price of Alloy 825 bar.	As a well-established, versatile alloy, its pricing is relatively stable and transparent. It offers a cost-effective solution for many applications where higher nickel alloys are not necessary.
Volume and Demand	High production volumes for this commonly specified alloy can lead to competitive pricing, especially for standard forms and sizes.	Consolidating orders or using standard stock sizes from Shanghai NC Metal Materials Co., Ltd. can yield favorable pricing.
Form, Size, and Condition	Cold-finished bars and large forging stock are more expensive than standard hot-rolled round bar. Material supplied in the annealed condition is standard.	For most applications, hot-rolled annealed round bar provides the best value. Specify cold-finished only if tight tolerances or superior surface finish are required.
Certification and Testing	Requirements for NACE MR0175 certification for sour service, or special corrosion testing, add to the base cost.	For oil & gas applications, NACE certification is often mandatory. For general chemical plant use, standard ASTM B425 certification is typically adequate.

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