ASTM A790 UNS S31803, UNS S32750 and UNS S32760 are duplex ( Ferritic/Austenitic ) steel grades, with high chromium and molybdenum elements, ASTM A790 UNS S31803 is the most widely used duplex stainless, it has excellent corrosion resistance, and high strength feature, generally S31803 stainless steel pipe is applied in corrosion and high-temperature environment. ASTM A790 UNS S32750 and ASTM A790 UNS S32760 are super duplex grades.
ASTM A790 standard state welded and seamless pipe dimensions conforming to ANSI B36.19, outside diameter range from NPS 1/8 to NPS 30, pipe schedules have Sch 5S, SCH10S, SCH40S, and SCH80S, other pipe sizes can be offered on request. Dimensional tolerances of ASTM A790 pipe should conform to ASTM A999 in outside and wall thickness, The pipe shall be pickled free of scale. When bright annealing is used, pickling is not necessary, DONGSHANG stainless supply A790 standard welded and seamless pipe with high quality, dimensional accuracy and excellent finish.
ASTM A790 Duplex steel S31803 pipe, ASTM A790 Duplex steel S32205 pipe, ASTM A790 Duplex steel S31500 pipe, ASTM A790 Duplex steel S32550 pipe, ASTM A790 Duplex steel S32750 pipe, ASTM A790 Duplex steel S32760 pipe, Duplex stainless-steel tube S31803, Duplex stainless-steel pipe S32205, Duplex stainless-steel pipe S31500, Duplex stainless-steel pipe S32550, Duplex stainless steel tube UNS S32750, Duplex stainless-steel pipe UNS S32520
ASTM A790 UNS S31803 S32750 And S32760 Compositions
Duplex Stainless Steels are characterized by Austenitic stainless steels and Ferritic stainless steels, high chromium (18–30%) and molybdenum (up to 5%) and lower nickel contents (3% – 10%) than Austenitic stainless steels, there are Lean Duplex, Standard Duplex, Super Duplex and Hyper Duplex.
| UNS No | AISI | C | Si | Mn | P | S | Cr | Mo | Ni | Others |
|---|---|---|---|---|---|---|---|---|---|---|
| S32101 | LDX 2101 | 0.040 | 1.00 | 4.0/6.0 | 0.040 | 0.030 | 21.0/22.0 | 0.10/0.80 | 1.35/1.70 | N 0.20/0.25; Cu 0.10/0.80 |
| S32202 | DX 2202 | 0.030 | 1.00 | 2.00 | 0.040 | 0.010 | 21.5/24.0 | 0.45 | 1.00/2.80 | N 0.18.0.26 |
| S32205 | 2205 | 0.030 | 1.00 | 2.00 | 0.030 | 0.020 | 22.0/23.0 | 3.0/3.5 | 4.5/6.5 | N 0.14/0.20 |
| S32304 | 2304 | 0.030 | 1.00 | 2.50 | 0.040 | 0.030 | 21.5/24.5 | 0.05/0.60 | 3.0/5.5 | N 0.05/0.20; Cu 0.05/0.60 |
| S32404 | Uranus 50 | 0.04 | 1.0 | 2.0 | 0.030 | 0.010 | 20.5/22.5 | 2.0/3.0 | 5.5/8.5 | N 0.20; Cu 1.0/2.0 |
| S32520 | Uranus 52N+ | 0.030 | 0.80 | 1.50 | 0.035 | 0.020 | 24.0/26.0 | 3.0/4.0 | 5.5/8.0 | N 0.20/0.35; Cu 0.50/2.00 |
| S32550 | Ferralium 255 | 0.04 | 1.00 | 1.50 | 0.040 | 0.030 | 24.0/27.0 | 2.9/3.9 | 4.5/6.5 | N 0.10/0.25; Cu 1.50/2.50 |
| S32750 | 2507 | 0.030 | 0.80 | 1.20 | 0.035 | 0.020 | 24.0/26.0 | 3.0/5.0 | 6.0/8.0 | N 0.24/0.32; Cu 0.50 |
| S32760 | Zeron 100 | 0.030 | 1.00 | 1.00 | 0.030 | 0.010 | 24.0/26.0 | 3.0/4.0 | 6.0/8.0 | N 0.20/0.30; Cu 0.5/1.00; W 0.50/1.00 |
ASTM A790 Standard
ASTM A790 / A790M specification specify duplex welded and seamless steel pipe manufacturing, sizes, tolerances, and testing conditions.
The specification covers seamless and straight-seam welded ferritic/austenitic steel pipe for general corrosive service, particularly emphasizing resistance to stress corrosion cracking. The pipe shall be made by the seamless or an automatic welding process, with no addition of filler metal in the welding operation. Heat analysis shall be made to determine the percentages of the elements specified. Tension tests, hardening tests, flattening tests, hydrostatic tests and nondestructive electric tests shall be made to conform to the specified requirements.
ASTM A790 Duplex Stainless Steel Pipe Applications
Due to duplex stainless steel’s excellent corrosion resistance and high strength, duplex stainless steel pipe and tube are applied in harsh environments, even in chloride and sulfide environments.
Duplex stainless steel pipes are typically used in:
- Chemical processing, transport and storage
- Oil and gas exploration and offshore rigs
- Oil and gas refining
- Marine environments
- Pollution control equipment
- Pulp & paper manufacturing
- Chemical process plant
Duplex Stainless Steel Features
Duplex stainless steels have Austenitic and Ferritic stainless steel microstructure and possess properties in two groups of stainless steel, however, they are different.
Versus Austenitic
- Higher yield strength
- Greater corrosion resistance
- Stress corrosion cracking resistance
- Not common, used temperate under 250 C.
- Fabricability is not as good as Austenitic
- Strictly control heat treatment and welding process
- Price stability
Versus Ferritic
- Good toughness than Ferric, not hard
- Greater corrosion
- Fabricability is better
- Better weldability
- Wide usage than Ferritic
- Higher price
Corrosion Resistance
Duplex stainless steel is extremely corrosion resistant, including intergranular and stress corrosion cracking.
Heat Resistance
Duplex steel grades have a good performance in high temperatures and can be used at least -50°C low temperature, better ductility than the ferritic and martensitic grades.
Heat Treatment
The solution temperature is around 1100°C, and rapid cooling.
| UNS Designation | Temperature | Quench |
|---|---|---|
| S31803 | 1870-2010 °F [1020-1100°C] | Rapid Cooling In Air Or Water |
| S32205 | 1870-2010 °F [1020-1100°C] | Rapid Cooling In Air Or Water |
| S31500 | 1800-1900 °F [980-1040°C] | Rapid Cooling In Air Or Water |
| S32550 | 1900 °F [1040°C] Min. | Rapid Cooling In Air Or Water |
| S31200 | 1920-2010 °F [1050-1100°C] | Rapid Cooling In Water |
| S31260 | 1870-2010 °F [1020-1100°C] | Rapid Cooling In Water |
| S32001 | 1800-1950 °F [982-1066°C] | Rapid Cooling In Air Or Water |
| S32003 | 1850-2050 °F [1010-1120°C] | Rapid Cooling In Air Or Water |
| S32101 | 1870 °F Min | Quenched In Water Or Rapidly Cooling In Other Means |
| S32202 | 1870-1975 °F [1020-1080°C] | Rapid Cooling In Air Or Water |
| S32506 | 1870-2050 °F [1020-1120°C] | Rapid Cooling In Air Or Water |
| S32304 | 1700-1920 °F [925-1050°C] | Rapid Cooling In Air Or Water |
| S32750 | 1880-2060 °F [1025-1125°C] | Rapid Cooling In Air Or Water |
| S32760 | 2010-2085 °F [1100-1140°C] | Rapid Cooling In Air Or Water |
| S32950 | 1820-1880 °F [990-1025°C] | Rapid Cooling In Water |
| S32520 | 1975-2050 °F [1080-1120°C] | Rapid Cooling In Air Or Water |
Tensile And Hardness Requirements
| Grade | Tensile Strength, Min., Ksi [MPa] | Yield Strength, Min., Ksi [MPa] | Elongation In 2 In., Or 50mm, Min, % | Hardness, Max Brinell |
|---|---|---|---|---|
| S31803 | 90 [620] | 65 [450] | 25 | 290 |
| S32205 | 95 [655] | 70 [485] | 25 | 290 |
| S31500 | 92 [630] | 64 [440] | 30 | 290 |
| S32550 | 110 [760] | 80 [550] | 15 | 297 |
| S31200 | 100 [690] | 65 [450] | 25 | 280 |
| S31260 | 100 [690] | 65 [450] | 25 | 290 |
| S32001 | 90 [620] | 65 [450] | 25 | 290 |
| S32304 | 100 [690] | 65 [450] | 25 | 290 |
| S32750 | 116 [800] | 80 [550] | 15 | 310 |
| S32760 | 109 [750] | 80 [550] | 25 | 300 |
| S32950 | 100 [690] | 70 [480] | 20 | 290 |
| S32520 | 112 [770] | 80 [550] | 25 | 310 |
FAQ
ASTM A790 UNS S31803 is a duplex stainless steel, containing 22% chromium with medium to high strength and good resistance to general corrosion stress and corrosion cracking.
ASTM A790 UNS S32750 is a super duplex stainless steel with excellent corrosion resistance, high strength and good toughness. It belongs to the ASTM A790 standard, which was developed by the American Society for Testing and Materials (ASTM) specifically for duplex stainless steel tubes and pipes, especially those super duplex stainless steels containing about 22% chromium, 3% molybdenum, 5% to 6% nickel, and 0.15% to 0.25% nitrogen.