Views: 6 Author: Rachel Publish Time: 2024-08-08 Origin: Site
Alloy 2507 (UNS S32750) is a super duplex stainless steel with 25% chromium, 4% molybdenum, and 7% nickel designed for demanding applications which require exceptional strength and corrosion resistance, such as chemical process, petrochemical, and seawater equipment. The steel has excellent resistance to chloride stress corrosion cracking, high thermal conductivity, and a low coefficient of thermal expansion. The high chromium, molybdenum, and nitrogen levels provide excellent resistance to pitting, crevice, and general corrosion.
Duplex 2507 is a super duplex stainless steel designed for applications which demand exceptional strength and corrosion resistance. Alloy 2507 has 25% chromium, 4% molybdenum, and 7% nickel. This high molybdenum, chromium and nitrogen content results in excellent resistance to chloride pitting and crevice corrosion attack and the duplex structure provides 2507 with exceptional resistance to chloride stress corrosion cracking.
Usage of Duplex 2507 should be limited to applications below 600° F (316° C). Extended elevated temperature exposure can reduce both the toughness and corrosion resistance of alloy 2507. Duplex 2507 possesses excellent mechanical properties. Often a light gauge of S32750 material can be used to achieve the same design strength of a thicker nickel alloy. The resulting savings in weight can dramatically reduce the overall cost of fabrication.
2507 Duplex is highly resistant to uniform corrosion by organic acids such as formic and acetic acid. It is alsohighly resistant to inorganic acids, especially if they contain chlorides. Alloy 2507 is highly resistant to carbide-related intergranular corrosion. Due to the ferritic portion of the duplex structure of the alloy it is very resistant to stress corrosion cracking in warm chloride containing environments. Through additions of chromium, molybdenum and nitrogen localized corrosion such as pitting and crevice attack are improved. Alloy 2507 has excellent localized pitting resistance.
2507 should be hot worked between 1875°F and 2250°F. This should be followed by a solution anneal at 1925°F minimum and a rapid air or water quench.
Most of the common stainless steel forming methods can be used for cold working 2507. The alloy has a higher yield strength and lower ductility than the austenitic steels so fabricators may find that higher forming forces, increased radius of bending, and increased allowance for springback are necessary. Deep drawing, stretch forming, and similar processes are more difficult to perform on 2507 than on an austenitic stainless steel. When forming requires more than 10% cold deformation, a solution anneal and quench are recommended.
Duplex S32750 should be solution annealed and quenched after either hot or cold forming. Solution annealing should be done at a minimum of 1925°F. Annealing should be followed immediately by a rapid air or water quench. To obtain maximum corrosion resistance, heat treated products should be pickled and rinsed.
2507 possesses good weldability and can be joined to itself or other materials by shielded metal arc welding (SMAW), gas tungsten arc welding (GTAW), plasma arc welding (PAW), flux cored wire (FCW), or submerged arc welding (SAW). 2507 filler metal is suggested when welding 2507 because it will produce the appropriate duplex weld structure.
Preheating of 2507 is not necessary except to prevent condensation on cold metal. The interpass weld temperature should not exceed 300°F or the weld integrity can be adversely affected. The root should be shielded with argon or 90% N2/10% H2 purging gas for maximum corrosion resistance. The latter provides better corrosion resistance.
To understand what makes Super Duplex 2507 a superior alloy, I need to break down its unique chemical composition. The major constituents within Super Duplex 2507 include chromium, molybdenum and nickel, constituting almost 25 % chromium for corrosion resistance; about seven percent nickel thus enhancing both toughness and strength while four percent molybdenum improves its resistance against pitting as well as crevice corrosion. Similarly, the balance between iron and the existence of nitrogen stabilize the duplex structure giving it a balanced microstructure of austenite plus ferrite. This is critical because it integrates both mechanical properties found in austenitic stainless steels with corrosion resistance from ferritic stainless steels making it more robust under harsh environments. The chemical composition of stainless steel grade Super Duplex 2507 is outlined in the following table.
Element | Content (%) |
Chromium, Cr | 24 – 26 |
Nickel, Ni | 6 – 8 |
Molybdenum, Mo | 3 – 5 |
Manganese, Mn | 1.20 max |
Silicon, Si | 0.80 max |
Copper, Cu | 0.50 max |
Nitrogen, N | 0.24 – 0.32 |
Phosphorous, P | 0.035 max |
Carbon, C | 0.030 max |
Sulfur, S | 0.020 max |
Iron, Fe | Balance |
Some common applications of Duplex 2507 stainless steel include:
Desalination.
Oil and gas industry equipment, including offshore platforms, pipelines, and well casings.
Chemical processing equipment, especially for handling corrosive chemicals.
Pulp and paper industry, particularly bleaching process equipment.
Petrochemical industry applications, including PVC strippers.
Water desalination plants.
Power industry equipment, such as flue gas desulfurization (FGD) systems.
Marine components, including ship propellers and shafts.
Pollution control equipment such as scrubbers.
Fittings are crucial components for connecting and controlling the flow of fluids in pipelines and systems. This includes elbows, tees, stub-ends, returns, caps, crosses, reducers, and pipe nipples, among others. If you need any duplex steel S32750 products, please contact us. JN Alloy can provide you with steel pipes, steel plates, round bars, flanges and various pipe fittings. We also support customization according to drawings to create the products you need.