Alloy 925 INCOLOY® 925 – UNS N09925 / ASTM B805, B564

Alloy 925 INCOLOY® 925

Alloy 925 INCOLOY® 925 is a precipitation-hardenable nickel-iron-chromium alloy with additions of molybdenum, copper, titanium and aluminium. This alloy is designed to offer an excellent combination of mechanical strength and corrosion resistance.

Nickel provides resistance to chloride stress corrosion cracking, while the combination of nickel, molybdenum and copper ensures excellent resistance to reducing environments. Molybdenum improves resistance to pitting and crevice corrosion, while chromium offers protection against oxidising environments. The titanium and aluminium elements enable precipitation hardening, increasing the mechanical strength of the alloy.

Thanks to its resistance to sulphide corrosion and stress corrosion cracking in hydrogen sulphide (H₂S) environments, the alloy is widely used in the Oil & Gas sector for the production of tubulars, valves, couplings, packers and components for deep wells.

Reference standards:

  • ASTM B805 (bars and wires)
  • ASTM B564 (flanges and forgings)
  • ASME Code Case 2218 (pressure applications)
  • NACE MR0175 (corrosion resistance in sour environments)

Chemical composition (%)

Element Content (%)
Nickel (Ni) 42.0 – 46.0
Iron (Fe) 22.0 min
Chromium (Cr) 19.5 – 22.5
Molybdenum (Mo) 2.5 – 3.5
Copper (Cu) 1.5 – 3.0
Titanium (Ti) 1.9 – 2.4
Aluminium (Al) 0.1 – 0.5
Manganese (Mn) 1.0 max
Silicon (Si) 0.5 max
Niobium (Nb) 0.5 max
Carbon (C) 0.03 max
Sulphur (S) 0.03 max

Mechanical properties

Temperature (°C) Tensile strength (MPa) Yield strength (MPa) Elongation (%)
20 1254 892 32
300 1189 826 30
600 1099 782 32
900 1075 807 31

Heat treatments

  • Solution annealing: 980-1040°C for 30 min – 4 h, with air cooling or faster.
  • Ageing: 732-749°C for 6-9 h, controlled cooling to 621°C, holding for 18 h, followed by air cooling.
  • Hot forming: Temperature range between 870 and 1175°C, with controlled cooling.

Available forms

INCOLOY® Alloy 925 is available in the following forms:

Industrial applications

Thanks to its combination of high mechanical strength and corrosion resistance, INCOLOY® 925 is used in the following sectors:

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