ASTM A790 UNS S31803 S32750 S32760 Duplex Stainless Steel Pipe
ASTM A790 UNS S31803, UNS S32750 and UNS S32760 are duplex ( Ferritic/Austenitic ) steel grades, with high chromium and molybdenum elements, UNS S31803 is the most wide 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 Standard
ASTM A790 / A790M specification specify duplex welded and seamless steel pipe manufacturing, sizes, tolerances, testing condition.
The specification covers seamless and straight-seam welded ferritic/austenitic steel pipe for general corrosive service, with particular emphasis on 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 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 |
Chemical Composition % By Mass Max, unless a range or minimum is indicated.
ASTM A790 UNS S31803 Duplex Stainless Steel Pipe
ASTM A790 standard state welded and seamless pipe dimensions conforming to ANSI B36.19, outside diameter range from to 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.
Duplex Stainless Steel Pipe Applications
Due to duplex stainless steel excellent corrosion resistance and high strength, duplex stainless steel pipe and tube are applied in harsh environments, even in chloride and sulphide environments.
Duplex stainless steel pipe 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 stainless steel, however, there are different.
Versus Austenitic
- Higher yield strength
- Greater corrosion resistance
- Stress corrosion cracking resistance
- Not common, used temperate under 250 C.
- Fabricability not 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 are extremely corrosion resistant, including intergranular corrosion and stress corrosion cracking.
Heat Resistance
Duplex steel grades have a good performance in high temperature, and can be used down to at least -50°C low temperature, better ductility than the ferritic and martensitic grades.
Heat Treatment
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 |
