Alloy 31 • UNS N08031

Alloy 31 is an iron-nickel-chromium-molybdenum alloy with nitrogen addition. It has a pitting resistance in high chloride environments between those of super-austenitic stainless steels and nickel alloys. The alloy has very good corrosion resistance in mixed acid and high chloride environments. The material is approved in ISO 15156/ NACE MR0175 to test level VI for sour gas service.

Available tube product forms

Typical Applications

Typical manufacturing specifications

  • ASTM B626
  • ASTM B622
  • Also individual customer specifications.

Industries predominantly using this grade            

Technical Data

Mechanical Properties

Temper Annealed
Tensile Rm 94 ksi (min)
Tensile Rm 650 MPa (min)
R.p. 0.2% Yield 41 ksi (min)
R.p. 0.2% Yield 280 MPa (min)
Elongation (2.02 or 4D gl) 40 % (min)


Physical Properties (Room Temperature)

Specific Heat (0-100°C) 452 J.kg-1.°K-1
Thermal Conductivity 11.7 W.m -1.°K-1
Thermal Expansion 18.1 mm/m/°C
Modulus Elasticity 198 GPa
Electrical Resistivity 1.03 μohm/cm
Density 8.61 g/cm3


Chemical Composition (% by weight)

Element Min Max
C - 0.0015
Si - 0.3
Mn - 2
P - 0.02
S - 0.01
Cr 26 28
Cu 1 1.4
Fe Balance
Mo 6 7
N 0.15 0.25
Ni 30 32
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