S31254 F44 1.4547 254SMo Super duplex stainless steel plate sheet
Material grade: 254SMo duplex steelUSA: UNS S31254
German brand : 1.4547 Chinese brand: X1CrNiMoCuN20-18-7
S31254 F44 1.4547 254SMo two-phase stainless steel overview:
High molybdenum content and high chromium and nitrogen content make the 254SMO have excellent resistance to spot corrosion and crevice corrosion.The addition of copper improves corrosion resistance in some acids.In addition, due to its high nickel content and high chromium and molybdenum content, the 254SMO has good stress corrosion cracking resistance.Numerous field tests and extensive use have shown that, even at slightly higher temperatures, the 254SMO is highly crevices resistant in seawater, and only a few types of stainless steels have this property.The corrosion resistance of the 254SMO in acidic solutions and oxidized halide solutions required for bleaching processes such as paper is comparable to that of the most corrosion-resistant nickel-based and titanium alloys.Due to its high nitrogen content, the mechanical strength of the 254SMO is higher than that of other types of austenitic stainless steels.In addition, the 254SMO has high ductility and impact strength as well as good weldability.The high molybdenum content of the 254SMO allows it to have a higher oxidation rate when annealed, thus having a rougher surface than ordinary stainless steel after pickling.But this has no adverse effect on the corrosion resistance of the steel.
S31254 F44 1.4547 254SMo Chemical composition of stainless steel
Metallographic structure of 254SMO:The 254SMO is a face-centered cubic lattice structure.In order to obtain austenite structure, the 254SMO is normally annealed at temperatures of 1150 to 1200 degrees Celsius.In some cases, the center of the material may have traces of metal mesophase.But in general, they have no adverse impact on impact strength and corrosion resistance.These phases may precipitate at grain boundaries when placed at temperatures between 600 and 1000 degrees Celsius.
S31254 F44 1.4547 254SMo two-phase stainless steel corrosion resistance:
The carbon content of the 254SMO is very low, which means that there is little risk of carbide precipitation from heating.The steel can pass the Strauss Test ASTMA262 specification E, even after being sensitized for one hour at 600-1000 degrees Celsius.However, due to the high alloy content of the steel.Metal mesophase may precipitate at grain boundary in the above temperature range.These deposits do not present the risk of intergranular corrosion of the steel when used in corrosive media.Therefore it can be welded without intercrystalline corrosion.But in hot concentrated nitric acid, these deposits may cause intercrystalline corrosion in the heat affected zone.In solutions containing chloride, bromide, or iodide, ordinary stainless steels are immediately subjected to local corrosion in the form of pitting corrosion, crevice corrosion, or stress corrosion cracking.However, in some cases, the presence of halides accelerates uniform corrosion.This is especially true in the presence of halides in non-oxidizing acids.In pure sulfuric acid, 254SMO has much greater corrosion resistance than 316 normal stainless steel.However, compared with type 904L (NO8904) stainless steel at high concentration, the corrosion resistance of type 254SMO is slightly weaker.In sulfuric acid containing chloride ions, 254SMO has the largest corrosion resistance.Due to the possibility of local and uniform corrosion, 316 ordinary stainless steel cannot be used in hydrochloric acid, but 254SMO can be used in diluted hydrochloric acid at normal temperature.There is no need to worry about pitting below the boundary.But try to avoid gaps.In fluorosilicic acid (H2SiF4) and hydrofluoric acid (HF), the corrosion resistance of ordinary stainless steel is very limited, while the 254SMO can be used over a wide range of concentrations and temperatures.
S31254 F44 1.4547 254SMo alloy is a versatile material that can be used in many industrial fields:
Petroleum and petrochemical equipment, such as bellows in petrochemical equipment.Pulp and paper bleaching equipment, such as pulp digester, bleaching equipment, filter washing drum and roller, etc.The main parts of flue gas desulfurization device in power plant are: tower body, flue, door plate, inner part, spraying system, etc.Offshore systems or seawater treatment, such as thin wall condensing pipes cooled by seawater in power plants, seawater desalination equipment, can be used even in equipment where seawater may not flow.Desalination industry, such as salt-making or desalination equipment.Heat exchangers, especially in working environments with chloride ions.