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Stainless Steel 904L Supplier Manufacturer | Alloy 904L | UNS N08904 | En 1.4539 | AISI 904L

UNS N08904, 904L Steel, Inox 904L, Manufacturer Supplier Stockist

Stainless Steel 904L | Alloy 904L | UNS N08904 | Steel 904L | AISI 904L | En 1.4539 

Originally developed to withstand environments containing dilute sulfuric acid, 904L Stainless Steel is a super austenitic stainless steel that is designed for moderate to high corrosion resistance in a wide range of process environments. With high chromium and nickel content, and additions of molybdenum and copper to this alloy steel, assures excellent corrosion resistance to corrosive media.

With the high percentage of nickel and molybdenum, Stainless Steel 904L is resistant to both mild and aggressive environments. Standards and Specifications for 904L steel – UNS designation UNS N08904, En number  – En 1.4539

904L is an austenitic stainless steel is a high-performance steel designed to sustain moderate to high corrosion resistance. Low carbon content improves it’s cleanliness and weld strength.

Trade names of 904L Stainless Steel :

  • Acier 904l
  • Inox 904L
  • Uranus B-6
  • Alloy 904L
  • WNR 1.4539
  • SAE 904L
  • 904L Alloy

Heat Resistance

Grade 904L stainless steels offer good oxidation resistance. However, the structural stability of this grade collapses at high temperatures, particularly above 400°C.

Heat Treatment

Grade 904L stainless steels can be solution heat-treated at 1090 to 1175°C, following by rapid cooling. Thermal treatment is suitable for hardening these grades.


Alloy 904L can be readily welded by most standard processes. Pre-heat and post-weld heat treatments for this grade are not required.  The corrosion resistance property of 904L stainless steel is impaired in certain environments due to the redistribution of nickel, molybdenum and chromium caused by the solidification of material after welding, although this is less evident in 904L grade. SS 904L electrodes and rods are used for welding grade 904L steels according to AS 1554.6.

Fabrication of 904L Alloy Steel

This grade can be machined using any standard methods, slow speeds and positive feed minimises the alloy’s tendency to work harden and glaze. The cold work hardening rate of 904L Alloy makes it less machinable than 410 and 304 stainless steels.

Hot working
For Hot working process of 904L a temperature range of 1562–2102°F is recommended .Hot working is followed a solution anneal and quench but 904L stainless steel may be used without subsequent heat treatment if the hot forming is discontinued above 2012°F and the material is quenched directly thereafter. In the event of partial heating or cooling below 2012°F, or if the cooling has been too slow, hot working should always be followed by a solution anneal and quenching. 904L should be solution annealed at 1940–2084°F.

Cold working
904L is quite ductile and forms easily. The addition of molybdenum and nitrogen implies more powerful processing equipment may be necessary when compared with the standard 304/304L grades.

This alloy does not respond to heat treatment. It may only be hardened by cold reduction.


Stainless Steel 904L Chemical Composition:


Stainless Steel 904L  Physical properties:

Elastic Modulus

Mean Co-eff of Thermal Expansion (µm/m/°C)
Thermal Conductivity
At 20°C11.5
At 500°C
Specific Heat 0-100°C
Elec Resistivity

Stainless Steel 904L Mechanical Properties:

Tensile Strength (MPa) minYield Strength 0.2% Proof (MPa) minElongation (% in 50mm) minHardness
Rockwell B (HR B)
Brinell (HB)
4902203670-90 typical150

Stainless Steel 904L Applications:

  • Bed Furnaces
  • Petroleum and Petrochemical refineries for catalytic recovery systems, flares, recuperators, tube hangers
  • Sintering/Cement Plants – burner shields, burners, wind boxes feeding and discharging systems
  • Nuclear Components
  • Thermocouples
  • Heat Exchange
  • Chlorination Equipment
  • pharmaceuticals
  • Oil extractions
  • Power Plant

Stainless Steel 904L Industrial Product Range

Review Date
Reviewed Item
904L Stainless Steel Grade
Author Rating