Type 2205 (UNS S31803 and/or UNS S32205)
Description
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 Duplex 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 |
Standards
Typical standards for Duplex 2205 Stainless Steel
| ASTM A276 |
| ASTM A479 |
| ASME SA276 |
| ASME SA479 |