Duplex 2507 Stainless Steel (UNS S32750)
2507 stainless steel differs from traditional steel in that it is mostly formed in alloy form, belongs to the ferrite-austenitic duplex stainless steel family, combines numerous austenitic and ferritic steel qualities, and can be utilized in extremely severe environments.
2507 duplex stainless steel has a chromium content of 25%, a molybdenum content of 4%, and a nickel content of 7%. Because of its high chromium and molybdenum content, 2507 stainless steel resists pitting, crevice corrosion, and uniform corrosion well. Its two-phase microstructure ensures that the steel has great mechanical strength and resistance to stress corrosion cracking. Furthermore, it is resistant to chloride-pitting corrosion and has high thermal conductivity and low coefficient of thermal expansion.
S32750 duplex steel has more strength and corrosion resistance than S32205 duplex steel. It is more resistant to corrosion produced by diluted sulfuric acid combined with chloride ions than 904L. It has a higher yield strength but lower ductility than austenitic stainless steels. S32750 super duplex steel has a high impact strength but should not be used at temperatures exceeding 570 °F or 300 °C since continuous exposure to such temperatures can result in diminished toughness.
Chemical Composition (%) of Duplex 2507 Stainless Steel (UNS S32750)
| CHEMICAL COMPOSITION (%) | ||||||||||
| C, max | Mn, max | P, max | S, max | Si, max | Cr | Ni | Mo | N | Cu, max | Fe |
| 0.030 | 1.20 | 0.035 | 0.020 | 0.80 | 24.00-26.00 | 6.00-8.00 | 3.00-5.00 | 0.24-0.32 | 0.50 | Rest |
Mechanical Properties of Duplex 2507 Stainless Steel (UNS S32750)
| MECHANICAL PROPERTIES | ||||
| Tensile Strength, MPa, min | Yield Strength, MPa, min | Elongation (%), min | Hardness, max | |
| 795 | 550 | 15 | 270 HB | 29 HRB |
Physical Properties of Duplex 2507 Stainless Steel (UNS S32750)
| PHYSICAL PROPERTIES | |||||
| Density | Modulus of Elasticity | Poisson's Ratio | Coefficient of Thermal Expansion | Thermal Conductivity | Electrical Conductivity |
| 7.8 g/cm³ | 210 GPa | 0.27 | 12 µm/m·K | 15 W/m·K | 2.2% IACS |
Features of Duplex 2507 Stainless Steel (UNS S32750)
- High mechanical strength
- Good oxidation resistance
- Good resistance to high temperature
- Excellent resistance to pitting and crevice corrosion
- Excellent resistance to uniform corrosion
- Excellent resistance to stress corrosion cracking
- Good weldability
- High thermal conductivity
Applications of Duplex 2507 Stainless Steel (UNS S32750)
2507 duplex stainless steel is widely used in oil and gas, chemical industry, paper, energy, marine, and other industries.
- Heat exchangers
- Chemical liquid cargo ship piping system
- Seawater systems
- Desalination (desalination) equipment
- Combustion (exhaust) gas purification equipment
- Petrochemical equipment
- Mechanical parts with high strength and corrosion resistance
Equivalent Grades of Duplex 2507 Stainless Steel (UNS S32750)
| Grade | UNS | WERKSTOFF NR. | GB | EN | AFNOR |
| 2507 | S32750 | 1.4410 | 022Cr25Ni7Mo4N | X2CrNiMoN25-7-4 | Z3 CN 25.06 Az |
Corrosion Resistance of Duplex 2507 Stainless Steel (UNS S32750)
- Resistance to General Corrosion
2507 duplex stainless steel's high chromium and molybdenum content makes it highly resistant to organic acids such as formic acid and acetic acid for overall corrosion. Furthermore, 2507 stainless steel has excellent corrosion resistance to inorganic acids, particularly those containing chlorides. Duplex steel 2507 has better corrosion resistance to dilute sulfuric acid combined with chloride ions than 904L.
- Resistance to Intergranular Corrosion
Because of its reduced carbon content, 2507 duplex stainless steel is very resistant to carbide precipitation in intergranular heat treatments.
- Resistance to Stress Corrosion Cracking
Because of its duplex structure, 2507 stainless steel is particularly resistant to stress corrosion cracking. Because of its higher alloy composition, Duplex 2507 has greater corrosion resistance and strength than Duplex 2205.
Machinability of Duplex 2507 Stainless Steel (UNS S32750)
After hot or cold forming, 2507 duplex stainless steel requires solution annealing and quenching. Solution annealing should be carried out at a temperature of at least 1925 °F and promptly followed by air or water quenching. The heat-treated steel must be pickled and cleaned to guarantee the needed corrosion resistance.
Weldability of Duplex 2507 Stainless Steel (UNS S32750)
The weldability of 2507 duplex stainless steel is excellent. Many typical stainless steel forming procedures apply to S32750 as well. Welding processes such as SMAW, GTAW, PAW, FCW, SAW, and others are available. It is advised that when welding S32750, you use 2507/P100 metal, which will make an appropriate two-phase structure.
