Alloy 20 INCOLOY® 20 – UNS N08020 / ASTM B462, B463, B729

Alloy 20 INCOLOY® 20

Alloy 20 INCOLOY® 20 is a nickel-iron-chromium-based alloy with additions of molybdenum, copper, and niobium, designed to offer excellent corrosion resistance in aggressive chemical environments, particularly in the presence of sulfuric acid. The alloy is also resistant to corrosion from chlorides, nitric acid, and phosphoric acid.

Thanks to its resistance to stress corrosion cracking and crevice corrosion , INCOLOY® 20 is ideal for applications requiring high performance in acidic environments. The alloy is easily machinable and weldable and is commonly used for the production of heat exchangers, process piping, tanks, valves, and fittings.

Reference standards:

  • ASTM B462 (bars and forgings)
  • ASTM B463 (sheet and strip)
  • ASTM B729 (Seamless Pipe)
  • ASME SB-462, SB-463, SB-729

Chemical composition (%)

Element Content (%)
Nickel (Ni) 32.0 – 38.0
Chromium (Cr) 19.0 – 21.0
Copper (Cu) 3.0 – 4.0
Molybdenum (Mo) 2.0 – 3.0
Iron (Fe) Balanced
Carbon (C) 0.07 max
Niobium + Tantalum (Nb + Ta) 8 x C – 1.0
Manganese (Mn) 2.0 max
Phosphorus (P) 0.045 max
Sulfur (S) 0.035 max
Silicon (Si) 1.0 max

Mechanical properties

Temperature (°C) Tensile strength (MPa) Yield strength (MPa) Elongation (%)
20 620 300 40

Heat treatments

  • Annealing: 1800-1850°F (982-1010°C) with air cooling to maintain corrosion resistance.
  • Hot forming: Temperature between 760 and 1175°C.
  • Stress relieving: To reduce internal tension, recommended after cold working.

Available formats

INCOLOY® Alloy 20 is available in the following forms:

Industrial applications

Due to its excellent corrosion resistance, INCOLOY® 20 is widely used in the following industries:

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