Round bar, strip, tube, spheres, flanges, and forgings
.[/restab] [restab title="Physical Characteristics"]
|F44||650||300||35High molybdenum content and high chromium and nitrogen content make F44 has very good performance of resisting to pitting corrosion and crevice corrosion. Copper can be added to improve corrosion resistance in acid. Environment. Due to its high content of nickel and high percentage of chromium and molybdenum content, F44 has good resistance to stress corrosion.|
1. A lot of field experiments and extensive application experience has shown that even at a slightly higher temperature, F44 in sea water also has a very high resistance to crevice corrosion performance, every few kinds of stainless steel has this characteristics.
2.F44 in acid solution, such as paper bleaching for production and oxidizing halite solution, has a great corrosion resistant capability as well as nickel base alloy and titanium alloy.F44 has high nitrogen content, so its mechanical strength is higher than other types of austenitic stainless steel. In addition, the F44 also has high ductility and impact strength and good weld-ability.
3.F44 high molybdenum content can make them have a higher annealing oxidation rate, which make it more rough than ordinary stainless steel. But it does not affect corrosion resistant capability.
F44 of face-centered cubic lattice structure. In order to obtain austenite structure, F44 is generally in the 1150-1200 degrees Celsius temperature to be annealed. In some cases, the material center may have metal mesophase (χ and alpha phase). But in general, they are on the impact strength and corrosion resistance are not adversely affected. When placed in the range of 600-1000 degrees, the phase may be on the grain boundary precipitation.
F44 carbon content is very low, which means that caused by heating is a small risk of carbide precipitation. Even in the steel 600-1000 degrees Celsius after one hour sensitizing treatment still can pass the Strauss intergranular corrosion Test (Strauss Test ASTMA262 discipline E). However, because of the high alloy content of steel. Among the above temperature range metal phase may be on the grain boundary precipitation. These deposits will not make the steel used in corrosive medium occurs frequently in danger of intergranular corrosion. Crystal corrosion can not occur by welding. But in hot concentrated nitric acid, the sediment may cause intergranular corrosion in the heat affected zone. ordinary stainless steel appears pitting corrosion in contains such as chloride, bromide, or iodine ion in the solution. Crevice corrosion and stress corrosion cracks by local corrosion in the form of erosion. However, in some cases, the existence of halide will speed up the uniform corrosion especially in no oxidation under the condition of acid in the presence of halide. In pure sulfuric acid, F44 is much bigger than 316 type stainless steel with corrosion resistance. But compared with 904 stainless steel (NO8904), F44 corrosion resistant ability is weaker. In sulfuric acid containing chlorine ion, F44 have the greatest resistance to corrosion. Due to local corrosion may occur, 316 type stainless steel cannot be used in hydrochloric acid, but F44 under the general temperature can be used in dilute hydrochloric acid. Don't have to worry about in the area of the boundary lines of the following point corrosion. But must try to avoid the existence of the gap. In fluorosilicic acid (H2SiF4) and hydrofluoric acid (HF), the general scope of the corrosion resistance of stainless steel is very limited, while F44 in quite a wide range of concentration and temperature of the application.
F44 alloy is a kind of multi-purpose material, can be applied in many fields of industry:
1. The oil, petrochemical equipment, such as petrochemical equipment in the bellows.
2. Pulp and paper bleaching equipment, such as pulp digester, bleaching equipment, filtering, washing with bucket cylinder and roller, etc.
3. The power plant flue gas desulfurization device, main parts are: absorption tower of the tower body, the flue, door plank, internals, spray system, etc.
4. The sea systems or water treatment, such as power plant using thin wall condensation pipelines, cooling sea water desalination processing equipment may not flow, even in the sea can also be applied in the system.
5. Desalination industry, such as salt or desalination equipment.
6. Heat exchanger, especially in heat exchanger with chloride ion work environment