ASTM B424 covers rolled nickel-iron-chromium-molybdenum-copper alloy (UNS N08825, UNS N08221, and UNS N06845) plate, sheet, and strip. These materials, commonly known as Incoloy 825 and related alloys, offer exceptional corrosion resistance in aggressive environments including sulfuric acid, phosphoric acid, and seawater.

Quick Specifications

Materials: UNS N08825 (Alloy 825), UNS N08221, UNS N06845
Product Forms: Plate, Sheet, Strip
Manufacturing: Hot-rolled or cold-rolled, annealed
Applications: Chemical processing, marine, oil & gas, pollution control

Chemical Composition (ASTM B424)

Element	UNS N08825 (Alloy 825) %	UNS N08221 %	UNS N06845 %
Nickel (Ni)	38.0 - 46.0	38.0 - 46.0	38.0 - 46.0
Chromium (Cr)	19.5 - 23.5	19.5 - 23.5	19.5 - 23.5
Iron (Fe)	22.0 min	22.0 min	22.0 min
Molybdenum (Mo)	2.5 - 3.5	2.5 - 3.5	2.5 - 3.5
Copper (Cu)	1.5 - 3.0	1.5 - 3.0	1.5 - 3.0
Titanium (Ti)	0.6 - 1.2	0.6 - 1.2	0.6 - 1.2
Aluminum (Al), max	0.2	0.2	0.2
Carbon (C), max	0.05	0.05	0.05
Manganese (Mn), max	1.0	1.0	1.0
Silicon (Si), max	0.5	0.5	0.5
Sulfur (S), max	0.03	0.03	0.03

Mechanical Properties (Annealed Condition)

Property	UNS N08825	UNS N08221	UNS N06845
Tensile Strength, min (MPa)	585	585	585
Yield Strength (0.2% offset), min (MPa)	240	240	240
Elongation in 2 in. (50 mm), min (%)	30	30	30
Hardness, max (HB)	200	200	200

Available Products (ASTM B424)

Alloy 825 (UNS N08825) Plate

Thickness: 3mm - 100mm
Width: Up to 2000mm
Length: Up to 6000mm
Hot Rolled, Annealed, Pickled (HRAP)

Alloy 825 (UNS N08825) Sheet

Thickness: 0.5mm - 3mm
Cold Rolled, Annealed, Pickled (CRAP)
2B or Bright Annealed finish

Alloy 825 (UNS N08825) Strip

Thickness: 0.1mm - 3mm
Precision rolled for specific applications
Coil or cut-to-length available

Corrosion Resistance

ASTM B424 alloys (especially UNS N08825) provide excellent resistance to:

Reducing Acids: Sulfuric acid, phosphoric acid
Oxidizing Acids: Nitric acid (with limitations)
Seawater: Pitting and crevice corrosion resistance
Chloride Stress Corrosion Cracking: Superior resistance
Intergranular Corrosion: Stabilized with titanium

Applications

Chemical Processing

Sulfuric acid production equipment
Phosphoric acid evaporators
Pickling equipment
Heat exchangers

Oil and Gas Industry

Offshore platform components
Seawater cooling systems
Sour gas service
Downhole equipment

Pollution Control

Flue gas desulfurization systems
Waste incineration equipment
Scrubbers and stacks

Marine Applications

Seawater cooling pipes
Saltwater intake systems
Marine exhaust systems

Heat Treatment

Annealing: ASTM B424 materials should be annealed at:

Temperature: 1800-1900°F (980-1040°C)
Cooling: Rapid cooling (water quench or air cool)
Purpose: Dissolve precipitates, optimize corrosion resistance

Note: Material should not be used in the as-welded condition for corrosive service without subsequent solution annealing.

Manufacturing Process

Melting: VIM (Vacuum Induction Melting) + ESR (Electroslag Remelting)
Hot Rolling: Slabs are hot rolled to plate/sheet dimensions
Cold Rolling: Precision cold rolling for sheets and strips
Annealing: Solution annealing to optimize properties
Pickling: Descaling and surface finishing
Inspection: 100% ultrasonic testing, dimensional inspection

Welding

ASTM B424 materials are weldable using:

Shielded Metal Arc Welding (SMAW): Use ENiCrMo-3 (Inconel 112) electrodes
Gas Tungsten Arc Welding (GTAW): Use ERNiCrMo-3 (Inconel 625) filler
Gas Metal Arc Welding (GMAW): Use ERNiCrMo-3 wire

Important: Welds should be solution-annealed after welding for optimum corrosion resistance in severe environments.
 

Dimension Tolerances

Product Form	Thickness Tolerance	Width Tolerance	Length Tolerance
Plate (3-100mm)	±0.3mm to ±0.8mm	+10/-0mm	+20/-0mm
Sheet (0.5-3mm)	±0.05mm to ±0.15mm	+5/-0mm	+10/-0mm
Strip (0.1-3mm)	±0.02mm to ±0.10mm	+1/-0mm	Coil or custom

Testing and Inspection

Chemical Analysis: PMI (Positive Material Identification) testing
Tensile Test: ASTM E8/E8M
Flattening Test: For plates
Ultrasonic Testing: 100% UT as per ASTM A578/A435
Intergranular Corrosion Test: ASTM G28 (Practice A)
Hydrostatic Test: When applicable
Radiographic Test: For welds (if applicable)

Comparison: UNS N08825 vs N08221 vs N06845

Property	UNS N08825 (Alloy 825)	UNS N08221	UNS N06845
Mo Content	2.5-3.5%	2.5-3.5%	2.5-3.5%
Cu Content	1.5-3.0%	1.5-3.0%	1.5-3.0%
Ti Content	0.6-1.2%	0.6-1.2%	0.6-1.2%
Primary Use	General corrosion resistance	Similar to N08825	Similar to N08825

Related ASTM Standards

ASTM B423 - Nickel-Iron-Chromium-Molybdenum-Copper Alloy Seamless Pipe and Tube
ASTM B822 - Copper-Alloy Castings for General Applications
ASTM B163 - Seamless Tubes for Condensers and Heat Exchangers
ASTM B425 - Ni-Fe-Cr-Mo-Cu Alloy Rod and Bar

Frequently Asked Questions (FAQ)

Q: What is the difference between ASTM B424 and ASTM B168?

A: ASTM B424 covers Ni-Fe-Cr-Mo-Cu alloys (Alloy 825), while ASTM B168 covers Ni-Cr-Fe alloys (Inconel 600/601). Alloy 825 has better resistance to sulfuric and phosphoric acids.

Q: Can ASTM B424 materials be used in seawater applications?

A: Yes, UNS N08825 has excellent resistance to seawater corrosion, including pitting and crevice corrosion. It's widely used in offshore and marine applications.

Q: Is post-weld heat treatment required for ASTM B424?

A: For optimum corrosion resistance in aggressive environments, solution annealing after welding is recommended. For less severe service, as-welded condition may be acceptable.

Q: What are the equivalent standards to ASTM B424?

A: Equivalent standards include ASME SB-424, DIN 2.4858, and EN 2.4858. UNS N08825 is also known as Alloy 825, Incoloy 825, and Nicorros 825.

Q: What is the maximum operating temperature for ASTM B424 materials?

A: UNS N08825 can be used up to 1000°F (538°C) in oxidizing atmospheres. In reducing atmospheres, lower temperatures are recommended.

Request a Quote — ASTM B424 Alloy 825 Plate, Sheet, Strip

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