SS 904L Round Bar

Alloy 904L (UNS N08904) is a superaustenitic stainless steel that is designed for moderate to high corrosion resistance in a wide range of process environments. The combination of high chromium and nickel content, coupled with additions of molybdenum and copper, assure good to excellent corrosion resistance.
With its highly alloyed chemistry — 25% nickel and 4.5% molybdenum, 904L provides good chloride stress corrosion cracking resistance, pitting and general corrosion resistance superior to 316L and 317L molybdenum enhanced stainless steels.
Alloy 904L was originally developed to withstand environments containing dilute sulfuric acid. It also offers good resistance to other inorganic acids such as hot phosphoric acid as well as most organic acids. Alloy 904L is easily welded and processed by standard shop fabrication practices.
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Product Details


Material GradeSS 904L
Single Piece Length6 meter
Thickness/Diameter1-4 Inch
TechniqueHot Rolled

Common Applications of 904L

▲ Air Pollution Control — scrubbers for coal-fired power plants

▲ Chemical Processing — process equipment for the production of sulfuric, phosphoric, inorganic and organic acids and the production of phosphate-based fertilizers

▲ Metallurgical Processing — pickling equipment using sulfuric acid

▲ Oil and Gas Production — offshore process equipment

▲ Pharmaceutical Industry — process equipment

▲ Pulp and Paper — processing equipment

▲ Seawater and Brackish Water — condensers, heat exchangers and piping systems

904L Chemical Composition


Percent by Weight



0.09 maximum



2.00 maximum



0.045 maximum



0.035 maximum



1.00 maximum



19.00 - 23.00 maximum



23.00 – 28.00 maximum



1.00 – 2.00 maximum

Physical property



0.28 lb/in3

Melting Range

2372 – 2534 °F

Specific Heat Capacity at 32 - 212°F

0.11 Btu/lb/°F

Thermal Conductivity at 212°F

6.8 Btu/hr-ft-°F

Poisson's Ratio

Elastic Modulus at 68°F

28 x 106 psi

Fabrication Data

Alloy 904L can be easily welded and processed by standard shop fabrication practices.

● Cold Forming

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.

Hot Forming

Working temperatures of 1562 – 2102°F (850 –1150°C) are recommended for hot working processes. Normally hot working should be followed by a solution anneal and quench, but for 904L, if hot forming is discontinued at a temperature above 2012°F (1100°C) and the material is quenched directly thereafter, the material may be used without subsequent heat treatment. It is important that the entire workpiece be quenched from temperatures above 2012°F (1100°C). In the event of partial heating or cooling below 2012°F (1100°C), 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 (1060 –1140°C).


The cold work hardening rate of Alloy 904L makes it less machinable than 410 and 304 stainless steels.


Alloy 904L can be readily welded by most standard processes. Austenitic plate materials have a homogeneous austenitic structure with an even distribution of alloying elements. Solidification after welding causes the redistribution of certain elements such as molybdenum, chromium and nickel. These segregations remain in the cast structure of the weld and can impair the corrosion resistance in certain environments. Segregation is less evident in 904L, and this material is normally welded using a filler metal of the same composition as the base metal and can even be welded without filler metal.


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