Incoloy825 austenitic nickel-iron-chromium alloy
Features and applications overview:
Incoloy825 is an common engineering alloy with resistance to acid and alkali metal corrosion under oxidization and reduction environment. High nickel content of the alloy ensures an effective resistance to stress-corrosion cracking. The alloy has good corrosion resistance in various media, such as sulfur acid, phosphoric acid, nitric acid and organic acids, alkali metals such as sodium hydroxide, potassium hydroxide and hydrochloric acid solution. The comprehensive performance of the alloy is showed in the nuclear burning dissolver in which there are various corrosive media, for example sulfuric acid, nitric acid and sodium hydroxide are dealt in the same device. Incoloy825 is applied in various industrial fields as the using temperature does not exceed 550°C, for example, the heating tubes, containers, baskets and chains of sulfur acid picking plant, seawater-cooled heat exchanger, marine products pipeline system, acidic gas environment pipe, the heat exchanger, evaporator, washing pipe and snorkel pipe used in the production of phosphoric acid, air heat exchanger in the oil refining, flame retardant alloy used in food engineering, chemical process, high-pressure oxygen.
Incoloy825s similar grades:
NS142(China)、NC21FeDu (France)、W.Nr.2.4858 NiCr21Mo (Germany) NA16 (England)
Chemical composition, %:
Nickel........................................38.0-46.0
Chromium..................................19.5-23.0
Iron.............................................balance.
Molybdenum...............................2.5-3.5
Carbon........................................0.025 max
Manganese..................................1.0 max
Silicon..........................................0.5 max
Sulfur...........................................0.01 max
Phosphorus...................................0.02 max
Copper..........................................1.5-3.0
Aluminium....................................0.2 max
Titanium........................................0.6-1.2
Physical properties:
Density, g/cm3 .............................8.1
Melting Range, °C......................1370-1400
Thermal conductivity,
λ/(W/m•°C), at 100°C ................10.8
Specific heat, J/kg•°C...................440
Elastic modulus, GPa....................195
Electrical resistivity, μΩ•m..........1.37
Coefficient of linear expansion,
a/10-6°C-1, at 20-100°C..........14.1

Mechanical properties:(the minimum value detected at room temperature)
Tensile strength, σb/MPa..............550
Yield strength,σp0.2/MPa........250
Elongation,σ5 /%.............................35
Brinell hardness, HBS..........................≥200
The way of heat treatment is solution treatment
Available products and specifications:
Bar: ASTN B425, ASME SB425
Plate/Strip: ASTM B424, ASME SB424
Pipe: ASTM B423, ASTM B163, ASTM B704, ASTM B705, ASME SB423, ASME SB163.
The metallurgical structure of Incoloy 825:
Incoloy alloy 825 has a stable face-centered cubic lattice structure. The chemical compositions and appropriate thermal treatment ensure the corrosion resistance is not weakened by alloys sensitization.
The process performance and requirements of Incoloy 825:
1, If there are sulfur, phosphorus, lead or other low melting point metal while heating, Nicrofer 6023/6023H alloy will become brittle. These impurities come from the marking paint, chalk, lubricants, water, fuel, etc. The sulfur content of the fuel should be low, for example, the sulfur content in liquefied gas and natural gas should be ideally less than 0.1%g/m3, in city gas less than 0.25g/m3 , in liquefied petroleum gas less than 0.5g/m3.
2, The hot-working range for Incoloy alloy 825 is 900 to 1150°C. The cooling method is water cooling or rapid air cooling.3, Tungsten electrode inert gas welding, plasma arc welding, handmade sub-arc welding, metal inert gas welding and shielded metal-arc welding are all can be used. The pulsed arc welding is the preferred solution.