S31254 F44 1.4547 254SMo Ultra Duplex Stainless Steel Plate

 　　Material grade: 254SMo dual phase steel United States: UNS S31254

　　German brand: 1.4547 Chinese brand: X1CrNiMoCuN20-18-7

　　Overview of S31254 F44 1.4547 254SMo two-phase stainless steel:

　　The high content of molybdenum, chromium, and nitrogen endows 254SMO with excellent resistance to spot and crevice corrosion. The addition of copper improves the corrosion resistance of certain acids. In addition, due to its high nickel content and high chromium and molybdenum content, 254SMO has good stress corrosion cracking resistance. Many on-site tests and widespread use have shown that even at slightly higher temperatures, 254SMO is highly resistant to crevices in seawater, with only a few types of stainless steel having this performance. The 254SMO in acidic solutions and oxide halide solutions required for bleaching processes such as paper is comparable to that of most corrosion-resistant nickel based and titanium alloys. The mechanical strength of 254SMO is higher than that of other types of austenitic stainless steel. In addition, 254SMO has high ductility, impact strength, and good weldability. The high molybdenum content of 254SMO gives it a higher oxidation rate. After annealing, its surface is rougher than ordinary stainless steel, but this has no adverse effect on the corrosion resistance of the steel.

　　Chemical composition of S31254 F44 1.4547 254SMo stainless steel

　　C ≤ Silicon ≤ Manganese ≤ P ≤ S ≤ Chromium ≥ Nickel ≥ Mo ≥ N ≤ 0.02 0.80 1.00 0.03 0.01 19.5-20.5 4.5-6.5 6.0-6.5 0.18-0.22

　　The metallographic structure of 254SMO: 254SMO is a face centered cubic lattice structure. In order to obtain an austenitic structure, 254SMO is usually annealed at a temperature of 1150 to 1200 degrees Celsius. In some cases, there may be traces of metal intermediate phases in the center of the material, but they usually do not have an adverse effect on impact strength and corrosion resistance. When placed at a temperature of 600 to 1000 degrees Celsius, these phases may precipitate at grain boundaries.

　　Corrosion resistance of S31254 F44 1.4547 254SMo two-phase stainless steel:

　　The carbon content of 254SMO is very low, which means that the risk of carbide precipitation caused by heating is very low. Even after being sensitized at 600-1000 degrees Celsius for one hour, the steel can still pass the Strauss Test ASTMA262 specification E. Due to the high alloy content in the steel, metal intermediate phases may precipitate at grain boundaries within the above temperature range. These deposits do not pose a risk of intergranular corrosion of the steel when used in corrosive media, Therefore, welding can be carried out without intergranular corrosion. However, in hot concentrated nitric acid, these deposits may cause intergranular corrosion in the Heat-affected zone. In solutions containing chloride, bromide, or iodide, ordinary stainless steel will immediately undergo pitting and crevice corrosion. However, in some cases, the presence of halides will accelerate uniform corrosion, especially in the presence of halides in non oxidizing acids. In pure sulfuric acid, the corrosion resistance of 254SMO is much greater than that of 316 ordinary stainless steel. However, compared with high concentration 904L (NO8904) stainless steel, the corrosion resistance of 254SMO type is slightly worse; In sulfuric acid containing chloride ions, 254SMO has * * * * corrosion resistance. Due to the possibility of localized and uniform corrosion, 316 ordinary stainless steel cannot be used in hydrochloric acid, but 254SMO can be used in dilute hydrochloric acid at room temperature. Don't worry about pitting below the boundary, but avoid creating gaps. In fluorosilicic acid (H2SiF4) and hydrofluoric acid (HF), the corrosion resistance of ordinary stainless steel is very limited, while 254SMO can be used over a wide concentration and temperature range.



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