904 l N08904 1.4539 Super duplex stainless steel tube pipe
904L (N08904, 1.4539) super austenitic stainless steel contains 14.0-18.0% chromium, 24.0-26.0% nickel and 4.5% molybdenum.
904L super austenitic stainless steel is a kind of low carbon and high nickel and molybdenum austenitic stainless steel with no rust and acid resistance, which is a proprietary material imported from French H·S company.
It has good activation-passivation conversion ability and excellent corrosion resistance. It has good corrosion resistance in non-oxidizing acids such as sulfuric acid, acetic acid, formic acid and phosphoric acid, good pitting resistance in neutral chloride ion medium, and good crevice corrosion resistance and stress corrosion resistance.
Suitable for various concentrations of sulfuric acid below 70℃, under normal pressure resistance to any concentration, any temperature of acetic acid, and mixed acid formic acid and acetic acid corrosion resistance is also very good.
Super austenitic stainless steel 904L (00cr20ni25mo4.5cu, N08904, 1.4539) is a kind of high-alloy austenitic stainless steel with low carbon content and good corrosion resistance in dilute sulfuric acid.
Has the high chromium content and plenty of nickel content, the addition of copper makes it have strong ability to resist acid, especially for chloride clearance corrosion and stress corrosion cracking are highly resistant, not easy to appear, erosion and fracture pitting resistance slightly better than other steel grade, good machinability and weldability, can be used for pressure vessels.
904 l N08904 1.4539 Chemical composition of stainless steel
904L (N08904, 1.4539) super austenitic stainless steel metallographic structure:
904L (N08904, 1.4539) super austenitic stainless steel is completely austenitic structure, compared with the general austenitic stainless steel with high molybdenum content, 904L is not sensitive to the precipitation of ferrite and alpha phase.
904L (N08904, 1.4539) super austenitic stainless steel physical and mechanical properties:
1. 904L (N08904, 1.4539) super austenitic stainless steel density: 8.24g/cm3.
2. 904L (N08904, 1.4539) super austenitic stainless steel tensile strength: σb≥520Mpa.
3. 904L (N08904, 1.4539) super austenitic stainless steel yield strength:σ0.2≥216Mpa
4, 904L (N08904, 1.4539) super austenitic stainless steel elongation: δ≥35%.
Corrosion resistance of 904L (N08904, 1.4539) super austenitic stainless steel:
Because 904L carbon content is very low (maximum 0.020%), there will be no carbide precipitation in the case of general heat treatment and welding.
This eliminates the risk of intergranular corrosion that usually occurs after heat treatment and welding.
High chromium-nickel-molybdenum content and the addition of copper, so 904L can be passivated even in reductive environments such as sulfuric acid and formic acid.
The high nickel content makes it have lower corrosion rate in the active state.
904L of pure sulfuric acid can be used at temperatures up to 40 degrees Celsius in concentrations ranging from 0 to 98%.
The corrosion resistance of pure phosphoric acid in the concentration range of 0~85% is very good.
In industrial phosphoric acid produced by wet process, impurities have a strong influence on corrosion resistance.
Among all kinds of phosphoric acid, 904L is more resistant to corrosion than ordinary stainless steel.
In strong oxidizing nitric acid, 904L has lower corrosion resistance than the high alloy steel without molybdenum.
In hydrochloric acid, the use of 904L is limited to lower concentrations of 1-2%.
In this concentration range.
The corrosion resistance of 904L is better than that of conventional stainless steel.
904L steel has high resistance to spot corrosion.
It is also very resistant to crevice corrosion in chloride solution.
The high nickel content of 904L reduces the corrosion rate in pits and crevices.
Normal austenitic stainless steels may be sensitive to stress corrosion in a chlorine-rich environment at temperatures above 60 degrees Celsius. This sensitivity can be reduced by increasing the nickel content of stainless steels.
Due to its high nickel content, 904L is highly resistant to stress corrosion cracking in chloride solution, concentrated hydroxide solution and hydrogen sulfide rich environment.
904L (N0804,,14539) super austenitic stainless steel processing properties:
1. Welding performance: 904L (N08904, 1.4539) super austenitic stainless steel can be welded in various ways.
The most commonly used welding method is manual arc welding or inert gas shielded welding. The electrode or wire metal is based on the composition of the parent metal and has higher purity, and the requirement of molybdenum content is higher than that of the parent metal.
Generally, there is no need to preheat before welding, but in cold outdoor work, in order to avoid condensation of water vapor, joint parts or adjacent areas can be heated evenly.
Note that the local temperature should not exceed 100 ℃, so as not to lead to carbon accumulation and intercrystalline corrosion.
Small line energy, continuous and fast welding rate are used in welding.
Generally, there is no need for heat treatment after welding. If heat treatment is needed, it shall be heated to 110 0 ~ 1150℃ and cooled down quickly.
2, machining performance: 904L (N08904, 1.4539) super austenitic stainless steel machining characteristics similar to other austenitic stainless steel, the process of sticking knife and work hardening trend.
The cutting coolant should be vulcanized and chlorinated oil. The equipment and process should be premised on reducing work hardening.
Slow cutting speed and feed should be avoided during cutting.
904L (N0804,,14539) super austenitic stainless steel applications:
Petroleum and petrochemical equipment, such as reactors in petrochemical equipment;
Storage and transportation equipment for sulfuric acid, such as heat exchangers;
The main parts of flue gas desulfurization device in power plant are: tower body, flue, door plate, inner part, spraying system, etc.
Scrubber and fan in organic acid treatment system;
Sea water treatment equipment, sea water heat exchanger, paper industry equipment, sulfuric acid, nitric acid equipment, acid, pharmaceutical industry and other chemical equipment, pressure vessels, food equipment;
Centrifuges, reactors, etc. in pharmaceutical factories;
Food machinery for soy sauce jars, cooking wine, salt jars, equipment and dressings;
Equipment and components for strong corrosive medium of dilute sulfuric acid.