904L is an austenitic chromium-nickel stainless steel. It has high nickel and chromium content, which provides good corrosion resistance to a wide range of corrosive environments. The alloy has excellent weldability and formability, resulting in high strength and ductility after heat treatment. 904L has been successfully used in many applications where aggressive media are present such as chemical processing, pulp & paper manufacturing, oil & gas drilling rigs and marine environments because of its ability to withstand severe pitting from chloride induced stress cracking caused by exposure to chlorides at the grain boundaries inherent with wrought products formed by wire drawing operations following welding or fabrication processes. UNS N08904 (904L) is an austenitic stainless steel designed for moderate to high corrosion resistance. The family of 904L stainless steels consist of alloys made by adding aluminum and titanium to the nickel base. The addition of these elements gives this alloy the ability to be rapidly formed, welded, or hot-worked at temperatures as low as 1000°F (538°C). The 904L alloys have excellent corrosion resistance in a wide range of acidic environments as well as excellent mechanical properties at elevated temperatures. These alloys also provide higher strength than other stainless steels and have up to 50% lower corrosion rates than other commercial austenitic grades such as 304 or 304L (e.g., 304H). This alloy in particular was developed to resist corrosion in a wide range of acidic environments. UNS N08904 is a high-nickel, low-carbon austenitic stainless steel alloy that contains more than 18% chromium and 10% nickel. It was developed to resist corrosion in a wide range of corrosive environments, including those containing sulfuric acid, hydrochloric acid, phosphoric acid, acetic acid, and citric acids. UNS N08904 is used in the chemical processing industry because it can withstand harsh chemicals at high temperatures without corroding or degrading over time. The alloy also has good resistance to chloride stress corrosion cracking thanks to its high nickel content. It has probably the lowest intrinsic corrosion rate of any commercial stainless steel and even competes, in some cases, with nickel-based superalloys. This is a low carbon alloy that has lower chromium content than 304 stainless steel and higher nickel content than 304 stainless steel. It also has higher copper content than 304 stainless steel. UNS N08904 is a low carbon alloy that contains 18% to 20% chromium and 5% to 7% nickel. It is used in applications involving high temperatures, where the austenitic structure provides improved creep strength over other grades of stainless steel with lower nickel content, such as UNS S30400 (304). The lower carbon content of this alloy makes it easier to work than standard, austenitic grade 304. Consequently, it is used for low-carbon applications where higher strength and hardness are not required. UNS N08904 can also be used for medium-carbon applications requiring high strength and good resistance to corrosion. This application may require post-weld heat treatment depending on the amount of cold work and solution annealing that has taken place. UNS N08904 resists general corrosion in fresh water service with no pitting or crevice corrosion at the maximum operating temperature of 1150°F (600°C). The alloy is an iron, nickel and chromium alloy with additions of copper and molybdenum as well. Nickel and chromium are the primary alloying elements in UNS N08904. When combined, they produce a solid solution strengthening effect that provides toughness, strength, good ductility and resistance to ablation at high temperatures. The addition of copper improves weldability while adding molybdenum improves toughness. Its low carbon content helps reduce carbide precipitation during welding. The low carbon content in UNS N08904 allows for better weldability than standard austenitic grade 304. It is also a superaustenitic stainless steel that possesses high levels of both chromium and nickel, making it highly resistant to corrosion. The addition of molybdenum gives the material enhanced strength, even at elevated temperatures. It is a superaustenitic stainless steel that possesses high levels of both chromium and nickel. UNS N08904 is a superaustenitic stainless steel that possesses high levels of both chromium and nickel. This alloy offers excellent formability, toughness and weldability. It is also nonmagnetic which makes it an ideal material for applications where magnetic properties are undesirable. UNS N08904 has a higher level of resistance to corrosion than most other stainless steels because of its high content of chromium, nickel and nitrogen alloys. The alloy therefore combines the strength and ductility with creep resistance at high temperatures, making it suitable for use in many situations such as seawater or chemical-laden fluids. 904L is nonmagnetic, highly corrosion resistant and offers excellent formability, toughness and weldability. 904L is a superaustenitic stainless steel that has been approved in the United States by the American Society for Testing and Materials (ASTM), International Organization for Standardization (ISO), Canadian Standards Association (CSA) and British Standards Institute (BSI). It is nonmagnetic, highly corrosion resistant and offers excellent formability, toughness and weldability. 904L contains 18% chromium content in addition to high levels of both chromium and nickel which makes it suitable for use under high temperature conditions or where increased resistance to hot corrosion is needed. UNS N08904 has excellent properties for use in highly aggressive environments. So, what does this all mean to you? If you’re looking for a metal with great corrosion resistance and strength that can be used in any industry, look no further than UNS N08904. This material is the perfect choice for manufacturing parts that will be exposed to harsh environments, including agricultural equipment and oilfield equipment. UNS N08904 is a superaustenitic stainless steel that possesses high levels of both chromium and nickel. It is nonmagnetic, highly corrosion resistant and offers excellent formability, toughness and weldability. This alloy in particular was developed to resist corrosion in a wide range of acidic environments.
SS 904L Equivalent Grade
The datasheet below summarizes Rolex 904L stainless steel equivalent grade such as European EN (German DIN EN, British BS EN, French NF EN…), Chinese GB, ISO, Japanese JIS standard.
AISI 904L equivalent material
Grade (Steel Number)
ISO Name (ISO Number)
AISI SAE; ASTM
904L (UNS N08904)
EN 10088-2; EN 10088-3
GB/T 20878; GB/T 4237; GB/T 3280
Datasheet and Specification of 904L
The following data sheet summarizes the chemical composition, properties, heat treatment and equivalent grade of 904L stainless steel (SS904L).
Chemical Composition of 904L
The following data sheet gives SS 904L stainless steel chemical composition.
Chemical Composition, %
Bars and Shapes
Plate, Sheet, and Strip
Mechanical Properties of 904L
The following table lists Rolex 904L stainless steel (SS904L) mechanical properties such as yield strength, tensile strength, elongation and hardness.
AISI ASTM 904L Steel Mechanical Properties
Tensile Strength, MPa (ksi), ≥
0.2% Yield Strength, MPa (ksi), ≥
Elongation in 50 mm (2 in.), %, ≥
Rockwell Hardness (HRBW), ≤
904L (UNS N08904)
Bars and Shapes
Annealed, Hot-finished or cold-finished
Plate, Sheet, and Strip
Heat Treatment of 904L
Annealing: The recommended annealing temperatures for 904L wrought steel is 1095 °C (2000 °F).
Corrosion resistance of 904L stainless steel
Since the carbon content of 904L is very low (max. 0.020%), there is no carbide precipitation under general heat treatment and welding. This eliminates the risk of intergranular corrosion that occurs after general heat treatment and welding. Due to the high chromium-nickel-molybdenum content and the addition of copper elements, 904L can be passivated even in reducing environments such as sulfuric acid and formic acid. The high nickel content gives it a low corrosion rate even in the active state. In the concentration range of 0-98% pure sulfuric acid, 904L can be used at temperatures up to 40 degrees Celsius. In pure phosphoric acid in the concentration range of 0-85%, its corrosion resistance is very good. In industrial phosphoric acid produced by the wet process, impurities have a strong influence on the corrosion resistance. In all kinds of phosphoric acid, 904L corrosion resistance is better than ordinary stainless steel. In strongly oxidizing nitric acid, 904L has lower corrosion resistance compared to highly alloyed steel grades without molybdenum. In hydrochloric acid, the use of 904L is limited to a lower concentration of 1-2%. In this concentration range. 904L has better corrosion resistance than conventional stainless steels. 904L steel has a high resistance to pitting corrosion. Its resistance to crevice corrosion is also good in chloride solutions. 904L’s high nickel content reduces the rate of corrosion at pits and crevices. Ordinary austenitic stainless steels may be sensitive to stress corrosion in a chloride-rich environment at temperatures above 60 degrees C. This sensitization can be reduced by increasing the nickel content of the stainless steel. Due to the high nickel content, 904L has a high resistance to stress corrosion rupture in chloride solutions, concentrated hydroxide solutions and hydrogen sulfide-rich environments.
Processing performance of 904L
Welding performance of 904L
As with general stainless steel, 904L can be welded using a variety of welding methods. The most commonly used welding method for manual arc welding or inert gas shielded welding, welding rod or wire metal based on the composition of the base metal material and higher purity, molybdenum content requirements than the base material. Preheating is generally not necessary before welding, but in cold outdoor work, to avoid condensation of water vapor, the joint or the adjacent area can be uniformly heated. Note that the local temperature should not exceed 100 ℃, so as not to lead to carbon agglomeration, causing intergranular corrosion. Welding should use a small linear energy, continuous and fast welding rate. After welding generally do not need heat treatment, if heat treatment, must be heated to 1100-1150 ℃ after rapid cooling.
Matching welding consumables: welding rod (E385-16/17), welding wire (ER385).
Machinability of 904L 904L machining characteristics similar to other austenitic stainless steel, the process has a tendency to sticky tool and work hardening. Must use positive front angle carbide tools, sulfide and chlorinated oil as cutting coolant, equipment and process should be to reduce the premise of machining hardening. Slow cutting speed and tool feed should be avoided in the cutting process.
Tube sheetis a sealing surface between the pipe end of the heat exchanger and the tube bundle channel. When a tube bundle is inserted into the tube bundle channel, the pipe end of the heat exchanger is closely fitted with the tube sheet. Therefore, the form of sealing between the tube sheet and the pipe end should be closely matched. The tube sheet is an important part of the heat exchanger. It is used to make the pipe end closely fitted with the tube bundle channel, and it plays a role in sealing between different materials. The tube sheet can be made of various materials and has various forms, such as double-layer steel plate or single-layer carbon plate. It should be selected according to its performance requirements for use in different types of heat exchangers. It is usually made of stainless steel, carbon steel, titanium alloy, aluminum alloy and other materials. From the material point of view, it can be divided into two kinds: welded plate type and punching-pressing type. The main difference between them lies in whether they are welded or pressed on both sides by rollers. The former has high strength but not easy to process; while the latter has lower strength but easy to process by rolling machines such as presses or dies so that it is widely used today. When a tube bundle is inserted into the tube bundle channel, the pipe end of the heat exchanger is closely fitted with the tube sheet. Tube sheets are made of stainless steel, carbon steel, titanium alloy, aluminum alloy and other materials. Therefore, the form of sealing between the tube sheet and the pipe end should be closely matched. The tube sheet should be made of the same material as the pipe end. This will ensure that there is no reaction between the materials, which could result in corrosion or other damage to your system. The tube sheet should also be resistant to corrosion and not react with either the fluid being carried through it or any abrasive particles that may be present. Tube sheets are important for making heat exchangers because they are used to seal the pipe end of the heat exchanger. Tube sheets come in different forms and materials, depending on their use. Some tube sheets have a seal that is applied by bending it around the flange of a pipe, while others use gaskets or other forms of sealing methods.
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