General Description

Duplex S31803 is a chromium nickel molybdenum austenitic ferritic steel. It combines improved resistance to stress corrosion cracking, pitting, crevice corrosion and high strength in comparison with other stainless steels.

UNS S31803 is resistant to intergranular corrosion. It has better corrosion resistance than that of other austenitic stainless steels such as 316, with higher resistance to stress corrosion cracking to that of either 304 or 316 stainless steels. Pitting corrosion and crevice corrosion is higher than that of 316. Due to its higher corrosion resistance UNS S31803 has better fatigue strength in corrosive environments than that of other austenitic stainless steel specifications.

Duplex S31803 can be used as an alternative to standard stainless steel specifications in applications where higher strength and resistance to stress corrosion cracking is required. Widely used in the brewing, power generation, marine, petrochemical and chemical engineering industries. Typical applications include bushes, flanges, shafts and fasteners.

Chemical Composition

Grade Fe% Ni% Cr% Mo% N% C% Mn% Si% S% P%
Duplex S31803 Bal. 4.5-6.5 21.0-23.0 2.5-3.5 0.08-0.2 Max 0.03 Max 2.0 Max1.0 Max 0.02 Max 0.03

(PREN = % Cr + 3.3% Mo + 16% N)≥33.0


Grade UNS ASTM Werkstoff
Duplex S31803 S31803 F51 1.4462

Physical Properties

Grade Density
Duplex S31803 7.8 g/cm3

Mechanical Properties

Condition Tensile Strength Yield Strength σp0.2/MPa Elongation
Reduction% Hardness HB
Solution annealed Min 620 Mpa Min 450 Mpa Min 25% Min 45% Max 290

Our Production Standard

Standard Bar Forging Sheet/Plate

Size Range

Duplex S31803 bar, rod, forging, plate, sheet are available.

Duplex S31803 welding wire ER2209 is also available.

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