Wst. 1.4539

UNS N08904

Stock program:
3 – 38 mm OD
1/8” – 1.1/2” OD

ASTM A 269/A 213/A 1016
ASME SB-677/NACE MR0175/PED 97/23 EC

Maximum service temperature: 450°C / 824°F

Alloy 904L is a low carbon high alloy austenitic stainless steel, with an chromium, nickel, molybdenum and copper content, which is widely used in applications where the corrosion properties of alloy 316L and alloy 317L are not adequate. Although originally develop for greatly improved resistance to strong reducing acids, particularly sulphuric acid. The steel also has an very high resistance to a wide range of  environments. This feature has been verified that it is very successful after many years of practical applications, which has results that alloy 904L has been standardized in many countries.

Characteristics alloy 904L:

  • The high Mo and the addition of copper to this grade gives it greatly improved resistance to strong reducing acids, particularly aspheric acid
  • The steel is highly resistant to chloride attack, both pitting crevice corrosion and stress corrosion crashing
  • Good machine ability and weld ability
  • The austenitic structure of alloy 904L also gives this grade excellent  toughness, even down to cryogenic temperatures

Market applications:

  • Offshore, oil & gas
  • Chemical processes
  • Seawater cooling equipment
  • Control and instrumentation
  • Pharmaceutical
  • Pulp and paper processing

Technical details

Technical composition (%) Fe Cr Ni Mo Mn Cu Si P N C S
904L min Bal. 19.0 23.0 4.0 1.0 0.045
max 23.0 28.0 5.0 2.0 2.0 1.00 0.045 0.10 0.020 0.015
Mechanical properties 904L
Tensile strenght (mpa, min) nl 490 – 700
Yield strength (0.2% offset mpa, min) 220
Elongation (%, min) 35
Density / weight (g / cm3 / kg) 8.05