Type 2205 (UNS S31803 and/or UNS S32205)


2205 stainless steel (UNS S31803 and/or S32205) is a nitrogen-enhanced duplex stainless steel alloy and is the most widely used of the duplex stainless steels. The nitrogen serves to significantly improve the corrosion resistance of the alloy, especially in the welded condition. To impart the metallurgical benefits of nitrogen to both improved corrosion performance and as-welded properties, 2205 stainless steel can be produced to a 0.15% minimum nitrogen content compared to the ASTM range of 0.08-0.20% for S31803 and 0.14-0.20% for S32205. The minimum Cr, Mo and Ni contents of 2205 (22.0, 3.1 and 5.5% respectively) can satisfy the requirements of both the UNS S31803 and S32205 composition specifications.

When heat-treated properly, the composition of 2205 stainless steel produces a microstructure that consists of a nearly equal mixture of austenitic and ferritic phases. The microstructure and composition of 2205 provides corrosion resistance to many environments that is superior to Types 316 or 317, and a minimum yield strength that is more than double that of conventional austenitic stainless steels.

Chemical Composition

Chemical Composition (wt%) limits as specified in ASTM A276 and ASME SA276*

Element S31803 S32205
Carbon 0.030 0.030
Chromium 21.0-23.0 22.0-23.0
Nickel 4.5-6.5 4.5-6.5
Molybdenum 2.5-3.5 3.0-3.5
Manganese 2.00 2.00
Silicon 1.00 1.00
Nitrogen 0.08-0.20 0.14-0.20
Phosphorus 0.030 0.030
Sulfur 0.020 0.020

*Maximum, unless range is indicated

Physical Properties

Physical properties for Type 2205 Stainless Steel

Density, lb/in3 0.285
Modulus of Elasticity, psi 27.5 x 106
Coefficient of Thermal Expansion, 68-212˚F, /˚F 7.6 x 10-6
Thermal Conductivity, Btu/ft hr ˚F 11
Specific Heat, Btu/lb ˚F 0.10
Electrical Resistivity, Microhm-in 31.5

Mechanical Properties

Mechanical property requirements for annealed product as specified in ASTM A276 and ASME SA276

Property S31803 S32205
Yield Strength, min (ksi) 65 65
Tensile Strength, min (ksi) 90 95
Elongation, min (%) 25 25
Hardness, max. (HBW) 290 290


Typical standards for Type 2205 Stainless Steel