Incoloy Alloy 825 vs MONEL Alloy 400: A Comprehensive Comparison

Incoloy Alloy 825 vs MONEL Alloy 400

Incoloy Alloy 825 and MONEL Alloy 400 are two widely used materials in the world of special Nickel base alloys. Both alloys offer unique properties that make them suitable for specific applications that differ from each other.

This article aims to provide an in-depth comparison of Incoloy Alloy 825 and MONEL Alloy 400, examining their chemical compositions, mechanical properties, corrosion resistance, and typical applications.

PropertyIncoloy Alloy 825MONEL Alloy 400
Primary Alloying ElementNickel (Ni)Nickel (Ni)
Chemical CompositionNi: 38-46%, Cr: 19.5-23.5%, Mo: 2.5-3.5%, Fe: 22% min, Cu: 1.5-3%Ni: 63% min, Cu: 28-34%, Fe: 2.5% max
Mechanical PropertiesTensile Strength: 80 ksi min, Yield Strength: 32 ksi min, Elongation: 30% minTensile Strength: 70-85 ksi, Yield Strength: 25-50 ksi, Elongation: 35% min
Corrosion ResistanceExcellent in reducing and oxidizing environments, resistant to pitting, crevice corrosion, and SCCExcellent in seawater, hydrofluoric acid and alkalis, resistant to pitting, crevice corrosion, and SCC
ApplicationsChemical processing, oil and gas well piping, nuclear fuel reprocessing, pollution control, pickling equipment, acid productionMarine engineering, chemical processing, heat exchangers, valves and fittings, gasoline and fresh water tanks, chemical plant piping
CostModerate to highModerate
AdvantagesVersatile corrosion resistance, good mechanical properties, suitable for high-temperature applicationsHigh corrosion resistance, good mechanical properties, excellent in seawater and various corrosive media
PREN NumberApprox. 30-35Approx. 25-30

Chemical Compositions

The chemical compositions of Incoloy Alloy 825 and MONEL Alloy 400 determine their material properties and behavior under various conditions. Here is a summary of their chemical compositions:

Incoloy Alloy 825

  • Nickel (Ni): 38-46%
  • Iron (Fe): 22% min
  • Chromium (Cr): 19.5-23.5%
  • Molybdenum (Mo): 2.5-3.5%
  • Copper (Cu): 1.5-3%
  • Titanium (Ti): 0.6-1.2%
  • Carbon (C): 0.05% max
  • Manganese (Mn): 1% max
  • Silicon (Si): 0.5% max
  • Sulfur (S): 0.03% max
  • Aluminum (Al): 0.2% max

MONEL Alloy 400

  • Nickel (Ni): 63% min
  • Copper (Cu): 28-34%
  • Iron (Fe): 2.5% max
  • Manganese (Mn): 2% max
  • Carbon (C): 0.3% max
  • Silicon (Si): 0.5% max
  • Sulfur (S): 0.024% max

Mechanical Properties

The mechanical properties of Incoloy Alloy 825 and MONEL Alloy 400, such as tensile strength, yield strength, and elongation, play a crucial role in their performance and durability.

Incoloy Alloy 825

  • Tensile Strength: 80 ksi (550 MPa) min
  • Yield Strength (0.2% offset): 32 ksi (220 MPa) min
  • Elongation: 30% min

MONEL Alloy 400

  • Tensile Strength: 70-85 ksi (483-586 MPa)
  • Yield Strength (0.2% offset): 25-50 ksi (172-345 MPa)
  • Elongation: 35% min

Corrosion Resistance

Incoloy Alloy 825 and MONEL Alloy 400 exhibit excellent corrosion resistance in various environments. Their specific resistance properties are as follows:

Incoloy Alloy 825

  • Exceptional resistance to both reducing and oxidizing environments
  • Strong resistance to pitting and crevice corrosion
  • Resistant to stress corrosion cracking (SCC) in chloride-containing environments
  • Effective against sulfuric, phosphoric, and nitric acids

MONEL Alloy 400

  • Excellent resistance to a wide range of corrosive media, including seawater, hydrofluoric acid, and alkalis
  • Resistant to stress corrosion cracking (SCC) in many environments
  • Good resistance to pitting and crevice corrosion in chloride-containing environments

Typical Applications

Incoloy Alloy 825 and MONEL Alloy 400 are used in various applications due to their unique properties:

Incoloy Alloy 825

  • Chemical processing equipment
  • Oil and gas well piping
  • Nuclear fuel reprocessing
  • Pollution control equipment
  • Components in pickling equipment
  • Acid production components

MONEL Alloy 400

  • Marine engineering applications, such as fasteners and pump shafts
  • Chemical processing equipment
  • Heat exchangers
  • Valves and fittings
  • Gasoline and fresh water tanks
  • Piping systems in chemical plants


Incoloy Alloy 825 and MONEL Alloy 400 are both versatile materials with unique properties that make them suitable for specific applications. While Incoloy Alloy 825 offers excellent resistance to various acids and oxidizing environments, MONEL Alloy 400 is known for its exceptional resistance to seawater and a wide range of corrosive media.

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