904L Super Austenitic Stainless Steel
904L Super Stainless Steel Overview:
904L Super Austenitic Stainless Steel is a low-carbon, high-nickel, molybdenum austenitic stainless and acid-resistant steel, which is the introduction of the French H-S proprietary materials. Has a very good activation-passivation transformation ability, excellent corrosion resistance, in non-oxidizing acids such as sulfuric acid, acetic acid, formic acid, phosphoric acid has good corrosion resistance, in neutral chloride-containing media with good resistance to pitting corrosion, and at the same time has a good resistance to crevice corrosion and resistance to stress corrosion performance. It is suitable for various concentrations of sulfuric acid below 70℃, and has good corrosion resistance to acetic acid and mixed acid of formic acid and acetic acid of any concentration and any temperature under normal pressure.
Super austenitic stainless steel 904L is a kind of austenitic stainless steel with low carbon content and high alloy, which has good corrosion resistance in dilute sulfuric acid, and is specially designed for environments with harsh corrosion conditions. Has a high chromium content and sufficient nickel content, the addition of copper makes it has a strong acid resistance, especially for chloride interstitial corrosion and stress corrosion chipping has a high degree of resistance, not easy to etch spots and cracks, pitting corrosion resistance is slightly better than other steel types, has a good machinability and weldability, can be used for pressure vessels.
904L super stainless steel grade:
00Cr20Ni25Mo4.5Cu (national standard) , UNS N08904 (the American Institute of Motor Vehicle Engineers and the American Society for Testing and Materials in 1967 *** with the design of the standard), DIN1.4539 (German standard), SUS890L, Al-904L,, F904L, NAS 255
904L Super Stainless Steel Standard:
ASTM A240/ASME SA-240 (American Society for Testing and Materials Standards; the new standard categorizes it as a stainless steel series, and the original standard ASME SB- 625 categorizes it as nickel. 625 will be categorized as nickel-based alloy series), ASTM A276, ASTM A182/ASME SA-182, ASTM A312/ASMES A312, ASTM B625/ASME B625, ASTM B673/ASME B673
904L Super Stainless Steel Metallurgical Structure:?
904L is a completely austenitic organization, compared with the general austenitic stainless steel with high molybdenum content, 904L is insensitive to precipitation of ferrite and alpha phase.
904L Super Stainless Steel Processing Properties:
Welding Properties
As with stainless steels in general, 904L can be welded using a wide variety of welding methods. The most commonly used welding methods for manual arc welding or sui gas shielded welding, welding rod or wire metal based on the composition of the base material and higher purity, molybdenum content requirements than the base material. Preheating is generally not required before welding, but in cold outdoor work, in order to avoid the condensation of water vapor, joints or adjacent areas can be uniformly heated. Note that the local temperature should not exceed 10 0 ℃, so as not to lead to carbon agglomeration, causing intergranular corrosion. Welding is recommended to use a small line energy, continuous and fast welding rate. After welding generally do not need heat treatment, such as the need for heat treatment, must be heated to 110 0 ~ 1150 ℃ after rapid cooling.
Supporting welding materials and welding process: 904L welding selection of ER385 wire and E385 electrodes
Machining performance
904L machining characteristics are similar to other austenitic stainless steel, machining process, there is a tendency to stick knife and hardening of the process. Positive front angle carbide tools should be used, sulfurized and chlorinated oils as cutting coolant, equipment and processes should be used to reduce work hardening as a prerequisite. Slow cutting speeds and feeds should be avoided in the cutting process.
904L corrosion resistance and the main use of the environment:
904L is designed for corrosive conditions of harsh environments of a very low carbon content, high alloying austenitic stainless steel, better than the 316L and 317L with better corrosion resistance, while taking into account the price and performance, cost-effective. Due to the addition of 1.5% copper, it has excellent corrosion resistance to reducing acids such as sulfuric and phosphoric acids. It also has excellent corrosion resistance to stress corrosion, pitting and crevice corrosion caused by chloride ions, and good resistance to intergranular corrosion. In the 0-98% concentration range of pure sulfuric acid, 904L can be used up to 40 degrees Celsius. In 0-85% concentration range of pure phosphoric acid, its corrosion resistance is very good. In industrial phosphoric acid produced by wet process, impurities have a strong influence on corrosion resistance. In all kinds of phosphoric acid, 904L corrosion resistance is superior to ordinary stainless steel. In strongly oxidizing nitric acid, 904L has lower corrosion resistance compared to highly alloyed steels 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 steels. 904L steel has a high resistance to pitting corrosion. Its resistance to crevice corrosion in chloride solutions. The high nickel content of 904L reduces the rate of corrosion at pockmarks and crevices. Ordinary austenitic stainless steels can 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 high resistance to stress corrosion rupture in chloride solutions, concentrated hydroxide solutions and hydrogen sulfide rich environments.
904L application areas:
Petroleum, petrochemical equipment, such as petrochemical equipment in the reactor, etc., sulfuric acid storage and transportation equipment, such as heat exchangers, etc., power plant flue gas desulfurization devices, the main use of the parts are: absorption tower tower, flue, stall door panels, the inner parts of the shower system, etc., the organic acid treatment system of the Scrubbers and fans, seawater treatment devices, seawater heat exchangers, paper industry equipment, sulfuric acid, nitric acid equipment, acid production, the pharmaceutical industry and other chemical equipment, pressure vessels, food equipment, pharmaceutical factories: centrifuges, reactors, etc., plant-based food: soy sauce tanks, cooking wine, salt tanks, equipment and dressings, for dilute sulfuric acid, strong corrosive media 904L is a matching steel.
904L main specifications:
904L seamless pipe, 904L steel plate, 904L round steel, 904L forgings, 904L flanges, 904L rings, 904L welded pipe, 904L steel strip, 904L straight bar, 904L wire and supporting welding consumables, 904L round cakes, 904L flat steel, 904L hexagonal bar, 904L size head, 904L elbow, 904L tee, 904L machined parts, 904L bolts and nuts, 904L fasteners.