Alloy 925 (UNS N09925)


Alloy 925 is a precipitation-hardenable Nickel-Iron-Chromium Alloy with additions of Molybdenum, Copper, Titanium and Aluminium, supplied in the solution annealed and aged condition. The Titanium and Aluminium are specifically added to give a strengthening of the alloy during ageing, as Ni3(Al, Ti) gamma (‘ϒ’) prime precipitates form throughout the alloy matrix and greatly increases the hardness and strength in a similar way to Alloys K-500, 718 and 725.

Alloy 925 has excellent corrosion resistance consistent with Alloy 825. High levels of Nickel ensure protection against stress corrosion cracking, whilst the additional Molybdenum and Copper resist reducing environments, in the same way that Chromium resists oxidising environments. Molybdenum enhances resistance to pitting and crevice corrosion, lifting the Pitting Resistance Equivalent number (PREN) to above 26. With such a balanced composition, Alloy 925 is particularly suited to down-hole applications in sour gas wells , but can also be used in less aggressive applications as it resists general, pitting, crevice and stress corrosion cracking in most aqueous environments where chloride or sulphide ions may be present.

Key Features:

  • Corrosion performance is particularly suited to the sour environments of down-hole crude oil and natural gas wells
  • Very high-strength, applicable to tooling applications and reducing suspended load of critical components
  • Excellent resistance to stress corrosion cracking


  • Downhole equipment for corrosive/sour service such as valves, hangers, tool joints and packers
  • Marine and pump shafts
  • High strength fasteners
  • Chemical process industry components

Chemical Composition:

Cr Ni Mo Co Nb (+Ta) Ti W Cu C Mn N Si P S Fe Al
Min 19.5 42 2.5 0.08 1.9 1.5 0.1
Max 22.5 46 3.5 0.5 2.4 3 0.025 1 0.35 0.02 0.003 Bal 0.5

Mechanical Properties:

0.2% Proof Stress 758-965 N/mm2 110-140 ksi
Tensile Strength  965 N/mm2  140 ksi
Elongation, 5.65√S0 and 4D 18%
Reduction of Area 25%
Hardness  38 HRC max.
Impact Strength(-60oC) Longitudinal 47J av (43J min) 35 av (32 min)


  1. Testing shall be carried out in accordance with ASTM A370 (tensile), ASTM E18 (hardness)
  2. Minimum properties quoted (tested at room temperature in a longitudinal direction)
  3. Testing performed on each melt of material per heat treatment batch
  4. Minimum lateral hole expansion of 0.015” (0.38mm)
  5. Additional tests routinely undertaken:

– Macro-etching

– Microstructure certified free from acicular, secondary and laves phases

– Grain size determined to be equiaxed and predominantly ASTM2 or finer (ASTM E112 x100 magnification)

Physical Properties:

Density (Kg.m-1) 8080
Magnetic Permeability (20°C) 1.001
Young’s Modulus (N/mm2) 199
Specific Heat, 20°C (J/(g.K)) 435
Electrical Resistivity, 20°C (Ω-m) 1.17x10-6
Electrical Conductivity, 20°C (mΩ/mm2) 0.25 (1.48% IACS)
Thermal conductivity, 20°C (W/(m.K)) 12
Mean coefficient of thermal expansion, 20-100°C (m/m/K) 13.2x10-6


Datasheet - NA-Alloy 925

Datasheet - NA-Alloy 925