904L Industrial Metal Braided Wire Mesh/GFW Stainless Steel Wire Mesh/Filter Mesh/Screen Mesh/Wire Mesh Material and Application

904L Industrial Metal Braided Wire Mesh/GF W Stainless Steel Wire Mesh/Filter Mesh/Screen Mesh/Wire Mesh Material, Application
904L also known as UNS  N08904, DI N 1.4539, ASTM A240, nickel-based alloy, SUS890L;
904L material introduction: 
904L super austenitic stainless steel is a low-carbon, high-nickel, molybdenum austenitic stainless acid-resistant steel, which was introduced in FranceProprietary material of H ·S Company. It has good activation-passivation transition ability, excellent corrosion resistance, good corrosion resistance in non-oxidizing acids such as sulfuric acid, acetic acid, formic acid, and phosphoric acid, and good corrosion resistance in neutral chlorine-containing media. Excellent resistance to pitting corrosion, as well as good resistance to crevice corrosion and stress corrosion. It is suitable for sulfuric acid of various concentrations below 70°C. It can withstand acetic acid of any concentration and temperature under normal pressure and has good corrosion resistance in mixed acids of formic acid and acetic acid. 
Main ingredients: 20C r-24 N i-4.3Mo -1.5 C u 

Grades and standards: U N S  N 08904, DI N 1.4539, ASTM A240 (the new standard classifies it as a stainless steel series, the original standard ASME  SB -625 classifies it as nickel-based alloy series), SUS890L. 
Metallographic structure of 904L stainless steel: 904L has a completely austenitic structure. Compared with general austenitic stainless steel with high molybdenum content, 904L is not sensitive to the precipitation of ferrite and α phase. 
Physical and mechanical properties: Density: 8.24g/ c m3. Tensile strength: σ b ≥520Mpa. Elongation: δ≥35%.
904L
Corrosion resistance of 904L stainless steel: 
Since the carbon content of 904L is very low (maximum 0.020%), there will be no carbide precipitation under general heat treatment and welding. This eliminates the risk of intergranular corrosion that normally occurs after heat treatment and welding. Due to the high chromium nickel molybdenum content and the addition of copper, 904L can be passivated even in reducing environments such as sulfuric acid and formic acid.
The high nickel content also results in a lower corrosion rate in the active state. In pure sulfuric acid in the concentration range of 0~98%, the service temperature of 904L can be as high as 40 degrees Celsius. In pure phosphoric acid with a concentration range of 0~85%, its corrosion resistance is very good. In industrial phosphoric acid produced by wet processes, impurities have a strong impact on corrosion resistance. Among all kinds of phosphoric acid, 904L has better corrosion resistance than ordinary stainless steel. In strongly oxidizing nitric acid, 904L has lower corrosion resistance than highly alloyed steels that do not contain molybdenum. In hydrochloric acid, the use of 904L is limited to lower concentrations of 1-2%. within this concentration range.
The corrosion resistance of 904L is better than that of conventional stainless steel. 904L steel has high resistance to pitting corrosion. Its ability to resist crevice corrosion in chloride solutions is also very good. The high nickel content of 904L reduces the corrosion rate in pits and crevices. Ordinary austenitic stainless steel may be sensitive to stress corrosion in a chloride-rich environment at temperatures above 60 degrees Celsius. This sensitivity can be reduced by increasing the nickel content of the stainless steel. Due to the high nickel content, 904L has high resistance to stress corrosion cracking in chloride solutions, concentrated hydroxide solutions and hydrogen sulfide-rich environments. 
Matching welding consumables: welding rod (E 385-16/17), welding wire ( E R385). 
904L uses, application scope and application fields include: 
* Petroleum and petrochemical equipment, such as reactors in petrochemical equipment, etc. 
* Storage and transportation equipment for sulfuric acid, such as heat exchangers, etc. 
* The main parts used in power plant flue gas desulfurization equipment are: the tower body of the absorption tower, the flue, the baffle plate, the internal parts, the spray system, etc. 
* Scrubbers and fans in organic acid treatment systems. 
*Seawater treatment equipment, seawater heat exchangers, paper industry equipment, sulfuric acid, nitric acid equipment, sulfuric acid, pharmaceutical industry and other chemical equipment, pressure vessels, food equipment. 
*Pharmaceutical factory: centrifuge, reactor, etc. 

*Plant foods: soy sauce jars, cooking wine, salt shakers, equipment and dressings. 

Application notes of 904L 
1. Processing performance 
1.1 Welding performance 
is the same as that of general stainless steel. 904L can be welded using various welding methods. The most commonly used welding methods are manual arc welding or inert gas shielded welding. The welding rod or wire metal is based on the composition of the base metal and has higher purity, and the molybdenum content is required to be higher than the base metal. Preheating is generally not required before welding, but in cold outdoor operations, in order to avoid condensation of water vapor, the joint part or adjacent area can be heated evenly. Pay attention to the local temperature not exceeding 100℃ to avoid carbon accumulation and intergranular corrosion. When welding, small linear energy, continuous and fast welding speed should be used. Generally, heat treatment is not required after welding. If heat treatment is required, it must be heated to 1100~1150℃ and then cooled quickly. 
1.2 Machining performance The machining characteristics of 90 4L are similar to other austenitic stainless steels. There is a tendency for tool sticking and work hardening during the machining process. Carbide tools with positive rake angles must be used, and vulcanized and chlorinated oils should be used as cutting coolants. The equipment and processes should be based on reducing work hardening. Slow cutting speeds and feed rates should be avoided during the cutting process.