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Inconel 825

Inconel 825

ALLOY 825 | N08825 | 2.4858 | NICR21MO | NA 16 | XH38BT | ЭП703 | NCF 825 | NFE30C20DUM

Incoloy 825 is a nickel-chromium-iron alloy with highly stabilized chemical composition, which gives the alloy localized as well uniform resistance to various forms of corrosion. A very stable austenitic structure is retained, when an appropriate proportion of iron and nickel is added to the alloy.

The addition of molybdenum in fine amount gives the grade resistance to localized and general corrosion. The nickel content in the alloy makes sure that the added molybdenum is encumbered to develop its ferritic nature, thus ensuring nickel to form its austenitic structure.

Nickel also imparts the required toughness to the metal and restricts corrosion during the processes even under acidic conditions. It also helps in resisting chloride stress corrosion cracking. The copper content improves the machinability of the grade. The nickel-copper-molybdenum conjunction gives the alloy exceptional resistance to reducing environments. In addition to that, there is also titanium stabilization in the alloy which restricts the formation of carbides at the heat affected zone. The inter-granular corrosion attack, particularly after processes at high temperatures and welding, is highly resisted due to the stabilization. The chemical composition of the grade improves the overall working properties of the alloy even at moderately elevated temperatures. The balance in iron and nickel content makes the alloy known as both austenitic alloy as well as a nickel alloy.

The grade has lesser work hardening due to the copper content. It can be therefore used from cryogenic temperatures to slightly high temperatures without loss of mechanical properties. However, other alloys are not considered when creep-rupture properties are required. The alloy 825 is efficiently used up to 540°C, without much changes in its microstructure and ductility. The alloy also has good impact strength which can be suitably retained at cryogenic temperatures. Incoloy 825 can be easily forged to required shape by managing its temperature around 880-1200°C. A finishing forge is carried out around 870°C to ensure better corrosion resistance. Thereafter, stabilizing annealing can be done to give additional strength.

The alloy is furthered strengthened by cold working. The alloy is also easier to cold form than other stainless steels. The decrease in the modulus of elasticity is very less with an increase in the corresponding temperature. At 20°C, the modulus value is around 195 GPa while at 600°C, its value is around 160 GPa. The alloy grade also proves to be effective in terms of cost while providing resistance to almost all variable media.

  • Chemical properties
  • Physical properties
  • General data
  • Standards Specifications
  • Forms of Supply
  • Corrosion Resistance
  • Heat Treatment
  • Weldability
  • Machining
  • Applications
  • Possible grade alternatives
Grade   Ni C Cu Mn Si Cr Fe S Al Mb Tl
Inconel 825 Min. 38.0 -  1.5 - - 19.5  22.0 - - 2.5  0.6
Max. 46.0 0.05 3.0 1.0 0.50 23.5 - 0.03 0.2 3.5 1.2
Density 8.14 g/cm 3 / 0.294 lb/in 3
Melting Point 1370 -1400 (°C) / 2500 – 2550 (°F)
Specific Heat @ 70°F 0.105 Btu/lb/°F
Curie temperature < -196 (°C) / < -320 (°F)
Annealing 930 – 983 (°C) / 1700 – 1800 (°F)
Quench Rapid Air
Resistivity(μω.cm) (0-100 C°) 112
Young modulus E (gpa) (0-100 C°) 195
Shear modulus G (gpa) (0-100 C°) 75
Standard 825
UNS N08825
WERKSTOFF NR. 2.4858
EN NiCr21Mo
BS NA 16
GOST XH38BT
JIS NCF 825
AFNOR NFE30C20DUM
OR ЭП703
Pipes & Tubes
Summary Standards
Standard Specification for Seamless Nickel and Nickel Alloy Condenser and Heat-Exchanger Tubes ASTM B163
Standard Specification for Nickel-Iron-Chromium-Molybdenum-Copper Alloy (UNS N08825 and N08221)* Seamless Pipe and Tube ASTM B423
Standard Specification for Welded UNS N06625, UNS N06219 and UNS N08825 Alloy Tubes ASTM B704
Standard Specification for Nickel-Alloy (UNS N06625, N06219 and N08825) Welded Pipe ASTM B705
Standard Specification for Electric Fusion Welded Nickel and Nickel Alloy Pipe ASTM B474
Fittings & Flanges
Summary Standards
Standard Specification for Factory-Made Wrought Nickel and Nickel Alloy Fittings ASTM B366
Standard Specification for Nickel Alloy Forgings ASTM B564

Piping and tubing, fittings and flanges, washers.

The composition of the alloy is resistant to various forms of corrosion in most aggressive environments. It can resist oxidizing as well as reducing environments like phosphoric acid and sulphuric acid. It can also resist sulphur containing flue gas, seawater and sour gas. The alloy has improved aqueous corrosion resistance than former grades. The localized corrosion attack like pitting and crevice corrosion are efficiently resisted. Inter-granular corrosion is very well resisted due to the presence of titanium stabilization in the alloy. The nickel content apart from general corrosion restricts chloride stress corrosion cracking. The fine amount of chromium gives resistance under nitric acid and nitrate environments. Resistance to oxidizing salt is also provided.

The alloy has titanium in its composition. Annealing can be carried at around 930-990°C. It is carried by rapid cooling to ensure maximum corrosion resistance. The grade is normally a stabilized anneal with a lower range of annealing around 940°C. Annealing is done below the full annealing range to obtain the maximum amount of titanium carbides and to avoid carbide precipitation at grain boundaries. However, softness and better grain structure is obtained by annealing at 980°C and above. Quenching might always not be required for thinner sections but is very important for thicker and larger sections to get rid of sensitization of carbides.

The alloy is conveniently weldable with standard procedures like MIG (metal inert gas), TIG (tungsten inert gas), SMAW (shielded metal arc welding), SAW (submerged arc welding). INCONEL filler metals are normally used. Joints should be properly cleaned to avoid contamination at the weld.

The alloy is moderately easy to machine. All the standard techniques can be readily used. It has optimum machining characteristics in the annealed condition. The alloy is specified as ‘C’ alloy and tooling specifications are relatively used. Positive feeds, rigid tooling, appropriate speeds, adequate lubrication will provide optimum results.

Chemical Processing, Acid production, Pickling tank heaters and equipment, Phosphoric acid evaporators, Nuclear fuel reprocessing, Oil and gas well piping, Pollution-control, Sulphuric acid piping and vessels, Propeller shafts, Tank trucks, Calorifiers, Electrostatic precipitator electrodes, Oil and gas recovery, Radioactive waste handling, Marine exhaust systems, ammonium sulphate vessels, Expansion Bellows, Power station ash hoppers, Hot vessels for food, water and seawater.

Incoloy 600
Grade   Ni C Cr Mn Si CU Fe S Al Ti

Incoloy 600

 Min. 30.00 - 19.00 - - - 39.50 - 0.15 0.15
Max. 35.00 0.10 23.00 1.50 1.00 0.75 - 0.015 0.60 0.60

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