ASTM A789 UNS S31803 Tubing

 

A789-S31803 is a designation under the Unified Numbering System (UNS) for stainless steel pipes. ASTM A789/A789M is the standard specification for seamless and welded ferritic-austenitic stainless steel pipes. S31803 is a grade of duplex stainless steel with a ferritic-austenitic microstructure. It features moderate strength, good impact toughness, and excellent overall and localized stress corrosion resistance. The yield strength is ≥450 MPa, which is 2 to 3 times that of austenitic stainless steel (316). This alloy is suitable for use in temperatures ranging from -45°C to 315°C. Therefore, this material is widely used in offshore module pipelines.

A789 UNS S31803 Duplex Stainless Steel Tubes Specification

Standard: ASTM A789, ASME SA789

Grade: UNS S31803

Stainless Steel Tubes Type: Seamless / Welded / ERW / EFW / Cold Draw / Hot Finish / Cold Finish

Outer Diameter Size: Seamless - 1/2" NB TO 18" NB
                                   Welded / ERW- 1" NB TO 16" NB
                                   EFW - 8" NB TO 110" NB

Wall Thickness: Schedule 10 to Schedule 160 (3 mm to 100 mm Thickness)

Length: 01 Meter to 12.5 Meters, Single Random Length, Double Random Length And Customize Size.

Tubes Ends: Plain Ends / Beveled Ends

Testing: Flattening Test, Bend Test, Hardness Test,Tensile Test

Chemical Composition of UNS S31803 Duplex Pipe

UNS Designation	Composition, %
	C Max	Mn max	P max	S max	Si max	Ni	Cr	Mo	N	Cu	Others
S31803	0.03	2	0.03	0.02	1	4.5-6.5	21.0-23.0	2.5-3.5	0.08-0.20	. . .	. . .

Heat Treatment Requirements of UNS S31803 Duplex Tube

UNS Designation	Temperature	Quench
S31803	1870-2010 °F [1020-1100°C]	Rapid cooling in air or water

A789 S31803 Duplex Stainless Steel Pipe

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

What is S31803 Duplex Stainless Steel?

S31803 duplex stainless steel is a moderately alloyed stainless steel with a microstructure comprising approximately equal parts ferrite and austenite. It combines the advantages of austenitic stainless steel and is not sensitive to brittleness. The addition of nitrogen in duplex stainless steel not only improves its resistance to pitting and stress corrosion cracking (SCC) but also prevents significant reduction in ductility and toughness due to severe grain coarsening in the heat-affected zone (HAZ) during welding. This grade is also not sensitive to weld heat cracking, thereby enhancing the corrosion resistance and mechanical properties of the HAZ.

S31803 duplex stainless steel exhibits superior SCC resistance, wear corrosion resistance, and corrosion fatigue resistance in many media compared to austenitic stainless steel. Its SCC resistance is particularly excellent in environments containing chloride ions (Cl-). Moreover, its resistance to H2S-induced SCC surpasses that of S30403 and S31603 grades.

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