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| AISI | Code | EN | Austenitic Stainless Steel |
| 904L | N08904 | 1.4539 |
AISI 904L (EN 1.4539 / UNS N08904) is a low-carbon, highly alloyed austenitic stainless steel developed for severely corrosive service conditions. It provides high resistance to general, pitting and crevice corrosion and is more resistant to chloride-induced stress-corrosion cracking than standard austenitic grades. The grade offers good formability and weldability; however, its pronounced work-hardening tendency requires suitable cutting tools and controlled machining parameters. It cannot be hardened by heat treatment, although its strength can be increased through cold working.
| C % | Si % | Mn % | P % | S % | Cr % | Ni % | Mo % | Cu % | N % | Fe % |
| ≤ 0.020 | ≤ 0.70 | ≤ 2.00 | ≤ 0.03 | ≤ 0.01 | 19.00–21.00 | 24.00–26.00 | 4.00–5.00 | 1.20–2.00 | ≤ 0.15 | Bal. |
- Chemical composition limits are specified in accordance with EN 10088-1
| Product Form | Rp0.2 [MPa] | Rm [MPa] | Elongation [%] | Density [g/cm³] |
| Bar – ≤160 mm | ≥230 | 530–730 | ≥35 | 8.0 |
| Plate – hot-rolled, ≤75 mm | ≥220 | 520–720 | ≥35 | 8.0 |
| Sheet – cold-rolled, ≤8 mm | ≥240 | 530–730 | ≥35 | 8.0 |
| Industry | Products |
| Chemical industry | Chemical storage tanks, process reactors, process piping systems |
| Petrochemical industry and oil refineries | Heat exchangers, valves, flanges and fittings |
| Pulp and paper industry | Bleaching tanks, bleaching towers, heat exchanger tubes |
| Fertilizer and phosphoric acid industry | Phosphoric acid tanks, evaporators, heat exchangers |
| Flue gas treatment and environmental technologies | Wet scrubbers, flue linings, gas ducts |
| Hydrometallurgy and mineral processing | Leaching tanks, acid transfer piping, process reactors |
| Food and beverage industry | Process tanks, heat exchangers, hygienic piping systems |
| Pharmaceutical industry | Process reactors, storage tanks, clean process piping |
904L occupies a technical position between standard austenitic stainless steels and more expensive nickel-based alloys. In the solution-annealed condition, it retains a fully austenitic structure and low magnetic permeability while also providing high toughness at cryogenic temperatures. Prolonged exposure above approximately 550 °C, however, may form intermetallic phases that can adversely affect mechanical properties and corrosion resistance. For this reason, 904L is selected for dependable service in severely corrosive conditions rather than for high-temperature strength.
AISI 904L, EN 1.4539, DIN X1NiCrMoCu25-20-5, UNS N08904
| Product Form | ASTM Specification |
| Bar | ASTM A276/A276M, ASTM A479/A479M |
| Plate | ASTM A240/A240M |
| Sheet | ASTM A240/A240M |
AISI 317 – EN 1.4449: A lower-alloyed and generally more economical option. However, it does not provide the same level of corrosion resistance as 904L, particularly in acidic environments.
Alloy 926 – EN 1.4529: Its higher molybdenum and nitrogen content provides greater resistance than 904L to pitting, crevice corrosion and chloride-bearing environments.
254 SMO / F44 – EN 1.4547: A higher-performance alternative to 904L, particularly in high-chloride environments and seawater applications.
Aperam – Super Austenitic Stainless Steel 904L
Note: The information contained in this datasheet is for informational purposes only; no liability is accepted.
