Views: 2 Author: Wang Publish Time: 2024-07-16 Origin: Site
Super duplex S32750 (2507) is a variant stainless steel alloy that is primarily used in the oil and gas industry, particularly for offshore platforms, heat exchangers, structural components, and architectural components. Along with very high tensile and yield strength ratings, super duplex S32750 resists stress corrosion cracking extremely well and is pitting resistant, highly weldable, and very versatile.
Supplied in the annealed condition, it achieves yield strengths of 80ksi (550Mpa), greater than most austenitic and duplex stainless steel grades. It cannot be hardened by heat treatment but can be strengthened by cold working. It also exhibits a low coefficient of thermal expansion and higher heat conductivity than austenitic steels and is suitable for working temperatures up to 300°C. Alloy 32750 is listed in NACE MR 0175 for sour service and having gained ASME Approval for Pressure Vessel applications it can be used in a wide variety of applications.
Alloy 32750 is a super duplex stainless steel supplied in the solution annealed condition. As a super duplex stainless steel, it combines the desirable aspects of both austenitic and ferritic grades. The higher chromium, molybdenum and nitrogen contents result in a Pitting Resistance Equivalent number (PREN) of >41, providing pitting and crevice corrosion resistance superior to austenitic and duplex stainless steels in almost all corrosive media, and a Critical Pitting Temperature exceeding 50°C.
UNS S32750 or 2507 Duplex is a super austenitic premium stainless that is similar to 2205 Duplex 2507 Stainless Steel is composed of 25% Chrome and 7% nickel which causes the alloy to have an even higher corrosion resistance and longer life span. Along with it being corrosion resistant, UNS S32750 has a high resistance of cracking and pitting, and the yield and tensile strength make it comparable to nickel alloys.
S32750 is the standard grade of super-duplex stainless steel based on 25% chromium, 7% nickel and significant additions of molybdenum, manganese and nitrogen. As with many of the duplex grades, S32750 also offers high strength and excellent resistance to chloride stress corrosion cracking, while the molybdenum and nitrogen levels enhance the pitting, crevice and general corrosion resistance.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 |
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.
Super Duplex F53 has more than twice the strength of conventional austenitic stainless steels in the annealed condition. It can also be provided in the cold-worked condition with yield strength exceeding 160 ksi. It maintains good toughness at temperatures down to -50°F (-10°C).
The high chromium content of duplex stainless steel S32750 that protects against corrosion, causes embrittlement at temperatures over about 300°C. At low temperatures duplex stainless steels have better ductility than the ferritic and martensitic grades. Duplex grades can readily be used down to at least -50°C.
Fabrication of duplex stainless steel S32750 should be done only with tools dedicated to stainless steel materials. Tooling and work surfaces must be thoroughly cleaned before use. These precautions are necessary to avoid cross contamination of stainless steel by easily corroded metals that may discolour the surface of the fabricated product.
Duplex stainless steel S32750 cannot be hardened by heat treatment. They can however be work hardened. Solution treatment or annealing can be done by rapid cooling after heating to around 1100°C.
Duplex stainless steel S32750 have good weldability. All standard welding processes can be used. They are not quite as easily welded as the austenitic grades but low thermal expansion in duplex grades reduces distortion and residual stresses after welding.
This super duplex grade has very high pitting and crevice corrosion resistance thanks to its high molybdenum and chromium content. It offers high strength but can also undergo embrittlement if exposed to high temperatures for an extended time. Grade 2507 duplex stainless steel is frequently used in extreme environments like desalination plants, seawater systems, and petrochemical industries. Typical applications include:
Chemical processing equipment: Grade 2507 is suitable for equipment used in producing and handling chemicals, acids, and solvents.
Oil and gas industry: It is used in offshore platforms, subsea equipment, and pipelines due to its resistance to corrosion in seawater and harsh environments.
Desalination plants: The alloy's corrosion resistance makes it suitable for use in desalination plants where it comes into contact with chloride-rich seawater.
Pulp and paper industry: Grade 2507 is used in equipment such as digesters, bleach washers, and evaporators due to its resistance to corrosive chemicals used in the papermaking process.
In conclusion, Super Duplex Stainless Steel S32750 is a popular choice for various industrial applications that require exceptional resistance to corrosion, high strength, and durability. They are cost-effective, long-lasting, and can be easily fabricated, making them an excellent choice for a wide range of projects. If you are planning to use Super Duplex Stainless Steel S32750 product in your next project, you can be confident that you are making the right choice. Consult JN Alloy for more information on Super Duplex Stainless Steel S32750 product and its properties.
JN Alloy is a distributor and product manufacturer of stainless steel, duplex steel, and nickel-based alloy raw materials, benefiting from strong upstream raw material advantages and rich domestic and foreign steel mill resources. If you have any questions about steel materials and products, please contact us.