Super duplex stainless steel grades have enhanced pitting and crevice corrosion resistance when compared with 300-series austeniticstainless steel or conventional duplex alloys. This can be attributed to the enhanced levels of chromium, molybdenum and nitrogen found in these materials. Alloy 2507 is the most common “super” duplex grade.
Usage of Super Duplex 2507 should be limited to applications below 6000 F (3160 C). Extended elevated temperature exposure can reduce both the toughness and corrosion resistance of alloy 2507.The high chromium, molybdenum, and nitrogen levels provide excellent resistance to pitting, crevice, and general corrosion.the duplex structure provides 2507 with exceptional resistance to chloride stress corrosion cracking.
Super Duplex 2507 possesses excellent mechanical properties. Often a light gauge of 2507 material can be used to achieve the same design strength of a thicker nickel alloy. The resulting saving in weight can reduce the overall cost of fabrication.
Super Duplex Stainless Steel Corrosion Resistance, The high chromium and molybdenum content of Super Duplex Stainless Steelmakes it extremely resistant to uniform corrosion by organic acids like formic and acetic acid. Super Duplex also provides excellent resistance to inorganic acids, especially those containing chlorides.
High resistance to chloride stress corrosion cracking
•High Strength
•Superior resistance to chloride pitting and crevice corrosion
•Good general corrosion resistance
•Suggested for applications up to 6000 F
•Low rate of thermal expansion
•Combination of properties given by austenitic and ferritic structure
•Good weldability and workability
2507 S32750 Super Duplex Stainless Steel Applications:
•High Strength
•Superior resistance to chloride pitting and crevice corrosion
•Good general corrosion resistance
•Suggested for applications up to 6000 F
•Low rate of thermal expansion
•Combination of properties given by austenitic and ferritic structure
•Good weldability and workability
2507 S32750 Super Duplex Stainless Steel Applications:
Super Duplex Stainless Steels and their characteristics
(1.4410) UNS S32750 2507 Super Duplex Stainless Steel Elbow 90 Degree
S32205 S31803(1.4462) Duplex Stainless Steel Pipes
S32304 (1.4362) Duplex Stainless Steel Pipes
S32304 (1.4362) Duplex Stainless Steel Pipes
| Sizes | Standard Tolerances | ||||||
| Products | OD | Wall | Lengths and/or coils | Grades | OD | Wall | Lengths |
| Pressure &Corrosion Tubing
Meets or exceeds requirements forwelded
Specification: ASTM-A789
| 1/16" (1.59 mm) to 4" (101.6 mm)
Metric sizes available
| 0.010" (0.25 mm) to 0.220" (5.59 mm) | Random or cut lengths up to 40' (12.2 m)
Coils to 1-1/2" OD
| Super Duplex 2507 |
<1-1/2" (38.1 mm) ±0.005" (0.13 mm)
1-1/2" (38.1 mm) to 3" (76.2 mm) ±0.010" (0.25 mm)
3-1/2" (88.9 mm) to 4" (101.6 mm) ±0.015" (0.38 mm)
| ±10% | Randoms up to +2" (50.8 mm)
Cuts +1/8" (3 mm) -0"
Coils to 80,000' (24,384 m)
|
| Subsea Umbilical Tubing
Specifications: ASTM-A789 and ASTM-A790
| 3/8" (9.53 mm) to 1-1/2" (38.1 mm) | 0.039" (0.99 mm) to 0.125" (3.18 mm) | Cut lengths to 60' (18.3 m)
Coils to 1-1/2" OD*
| Super Duplex 2507 | ±0.005" (0.127 mm) | ±10% | Coils to 80,000' (24,384 m) |
Physical Properties of 2507 S32750 Super Duplex Stainless Steel Pipes in the Annealed Condition at -20°F to +100°F
| Tensile Strength | Yield Strength | |||||||||||||
| Alloy | UNS | Spec. | psi | MPa | ksi | psi | MPa | ksi | Elongation in 2 in. (min.) % | Grain Size Req. | Max. Hardness | Modulus of Elasticity (x106 psi) | Mean Coefficient of Thermal Expansion (IN./IN./°F x 10-6) | Thermal Conductivity (BTU-in/ ft2-h-°F) |
| Super Duplex 2507 | S32950 | A789,A790 | 100,000 | 690 | 100 | 70,000 | 485 | 70 | 20 | — | 30.5 Rc | — | — | — |
| Super Duplex 2507 | S32750 | A789, A790 | 116,000 | 800 | 116 | 80,000 | 550 | 80 | 15 | — | 32 Rc | 27.5 | 7.2 | 98 |
Composition of 2507 S32750 Super Duplex Stainless Steel Pipes
| Grade | Super Duplex 2507 |
| UNS Designation | S32750 |
| Carbon (C) Max. | 0.030 |
| Manganese (Mn) Max. | 1.20 |
| Phosphorous (P) Max. | 0.035 |
| Sulphur (S) Max. | 0.020 |
| Silicon (Si) Max. | 0.80 |
| Chromium (Cr) | 24.0–26.0 |
| Nickel (Ni) | 6.0–8.0 |
| Molybdenum (Mo) | 3.0–5.0 |
| Nitrogen (N) | 0.24–0.32 |
| Iron (Fe) | Bal. |
| Copper (Cu) | 0.50 |
| Other Elements | — |
Super Duplex 2507 Product Range
| Alloy | UNS Designation | Werkstoff NR. | Specifications* |
| Super Duplex 2507 | S32750 | 1.4410 | A/SA789, A/SA790 |
*Note: The specifications noted including ASTM, ASME, or other applicable authorities are correct at the time of publication. Other specifications may apply for use of these materials in different applications.
Source: Zhejiang Yaang Pipe Industry Co., Limited (www.yaang.com)