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Duplex S31803/F51

Material: Duplex 2205, Grade S31083, DIN 1.4462, F51

Duplex Stainless steel S31803, also called duplex 2205, is a duplex grade with a ferritic-austenitic microstructure resists sulfide stress corrosion and chloride environments. Its temperature range is typically listed as -50° to 300° C (-58° to 572° F). Duplex S31803's micro-components experience precipitation with prolonged exposure to high temperatures, and ductility suffers with immersion in extremely cold environments.

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What Is UNS S31803?

UNS S31803, also known as F51, is a duplex stainless steel with a dual-phase microstructure consisting of approximately 50% austenite and 50% ferrite. This structure provides the material with an excellent combination of strength and corrosion resistance.

F51/S31803/1.4462 duplex stainless steel offers high strength, excellent impact resistance, and corrosion resistance. In harsh environments, its resistance to pitting, crevice corrosion, stress corrosion, and corrosion fatigue is superior to that of ordinary austenitic stainless steel. It also features a lower coefficient of thermal expansion and higher thermal conductivity. Therefore, it is widely used in oil and gas pipelines, heat exchange equipment, and pressure vessels.

S31803 Chemical Composition

Composition	Value
Carbon (C)	0.0 - 0.03
Chromium (Cr)	21.00 - 23.00
Manganese (Mn)	2.00 max
Silicon (Si)	1.00 max
Phosphorous (P)	0.0 - 0.03
Sulphur (S)	0.0 - 0.02
Nickel (Ni)	4.50 - 6.50
Nitrogen (N)	0.08 - 0.20
Molybdenum (Mo)	2.50 - 3.50
Iron (Fe)	Balance

S31803 Mechanical Properties

Tensile, min, ksi[MPa]	Yield, min, ksi[MPa]	Elongation, %(min)	Hardness, HB（max）
90 [620]	65 [450]	25	290

S31803 Equivalent Grades

STANDARD	WERKSTOFF NR.	UNS	EN
Duplex S31803	1.4462	S31803	X2CrNiMoN22-5-3

S31803 Standards And Prodcuts

Products	Standards	Show
Duplex S31803/F51 Pipe	ASTM A790
Duplex S31803/F51 Tube	ASTM A789
Duplex S31803/F51 Sheet	ASTM A240
Duplex S31803/F51 Bars	ASTM A276/A479
Duplex S31803/F51 Forgings/Flanges	ASTM A182
Duplex S31803/F51 BW Fittings	ASTM A815

S31803 Properties

Corrosion Resistance
Duplex stainless steels are extremely corrosion resistant. They have high resistance to intergranular corrosion. Even in chloride and sulphide environments, duplex stainless steels exhibit very high resistance to stress corrosion cracking. While the super duplex grades are even more resistant to corrosion.

Heat Resistance
The high chromium content of duplex stainless steels that protects against corrosion, causes embrittlement at temperatures over about 300°C. At low temperatures duplex stainless steels have better ductility than the ferritic and martensitic grades. Duplex grades can readily be used down to at least -50°C.

Heat Treatment
The solution treatment temperature is 1040-1100°C, and it must be quenched after heat treatment. The cooling rate should be as fast as possible, and the time of exposure to the brittle temperature range (475°C brittle temperature range, σ brittle temperature range) must be shortened.

Pickling
Pickling uses a mixture of nitric and hydrofluoric acids. Since the scale of S31803 is slightly more difficult to remove compared to SUS 304, it may be more effective to perform a short alkali immersion before pickling or, if possible, shot peening.