2205 duplex stainless steel (UNS S32305/S31803) is a duplex stainless steel composed of 22% chromium, 3% molybdenum and 5-6% nickel-nitrogen alloy. It has high strength, good impact toughness and good overall and local strong corrosion resistance.
Compared with 316L and 317L austenitic stainless steel, 2205 duplex stainless steel has superior performance in pitting corrosion and crevice corrosion, it has high corrosion resistance, and compared with austenitic, it has a lower coefficient of thermal expansion , the thermal conductivity is higher.
Compared to austenitic stainless steels, it has twice the compressive strength, and designers can save weight and cost less than 316L and 317L.
2205 (UNS S32205/S31803) 22% chrome, 3% molybdenum stainless steel
General Properties Application Areas Standard Corrosion Resistance Chemical Composition Mechanical Properties Structural CNC Machining And Welding
General properties 2205 duplex stainless steel is a duplex stainless steel machining composed of 22% chromium, 3% molybdenum and 5-6% nickel nitrogen. It has high strength, good impact toughness and good overall and local stress corrosion resistance. Compared with 316L and 317L austenitic stainless steel, 2205 duplex stainless steel has superior performance in pitting corrosion and crevice corrosion. It has high corrosion resistance and has a lower coefficient of thermal expansion than austenite. , higher thermal conductivity. The yield strength of 2205 is twice that of austenitic stainless steels, a feature that allows designers to reduce weight when designing products, making this alloy more affordable than 316, 317L. This alloy is particularly suitable for use in the -50°F/+600°F temperature range. For applications outside this temperature range, this alloy can also be considered, but there are some limitations, especially when applied to welded structures.
Application Field Of 2205 Duplex Stainless Steel
- oPressure vessels, high pressure storage tanks, high pressure pipes, heat exchangers (chemical machining industry).
- oOil and gas pipelines, heat exchanger cnc turning stainless steel fittings.
- o Sewage treatment system.
- o Pulp and paper industry classifiers, bleaching plants, storage and handling systems.
- o Rotary shafts, press rolls, blades, impellers, etc. in high-strength and corrosion-resistant environments.
- o Cargo boxes for ships or trucks
- o Food processing equipment
ASTM/ASME………..A240 UNS S32205/ S31803 EURONORM……..1.4462 X2CrNiMoN 22.5.3 AFNOR………… …….Z3 CrNi 22.05 AZ DIN ………………………W. Nr 1.4462
Corrosion Resistance Uniform Corrosion Due to the chromium content ( 22%), molybdenum (3%) and nitrogen content (0.18%), the corrosion resistance of 2205 is better than 316L and 317L in most environments.
Local corrosion resistance The content of chromium, molybdenum and nitrogen in 2205 makes it highly resistant to pitting and crevice corrosion in oxidizing and acidic solutions.
Corrosion curve 4 mpy (0.1 mm/yr) in sulfuric acid with 2000 ppm chloride
The dual-phase microstructure of stress-corrosion-resistant stainless steels contributes to improved resistance to stress-corrosion cracking of stainless steel parts. In the presence of certain temperature, stress, oxygen and chloride , austenitic stainless steel will undergo chloride stress corrosion. Since these conditions are not easily controlled, the use of 304L, 316L and 317L is limited in this regard.
Corrosion fatigue resistance The high strength and corrosion resistance of 2205 duplex stainless steel make it have a high corrosion fatigue resistance. CNC Machine is susceptible to corrosive environments and loading cycles, and the properties of 2205 are ideal for such applications.
Uniform Corrosion in Wet Machined Phosphoric Acid
corrosion rate , ipy | ||
| grade | Solution A, 1401/4F | Solution B, 1201/4F |
| 2205 | 3.1 | 3.9 |
| 316L | >200 | >200 |
| 904L | 47 | 6.3 |
| Ingredients , wt % | ||||
| P2O5 | HCl | HF | H2SO4 | Fe2O3 |
| Sun A 54.0 | 0.06 | 1.1 | 4.1 | 0.27 |
| Sol B 27.5 | 0.34 | 1.3 | 1.72 | 0.4 |
| Ingredients , wt % | ||||
| P2O5 | Al2O | SiO2 | CaO | MgO |
| Sun A 54.0 | 0.17 | 0.10 | 0.20 | 0.70 |
| Sol B 27.5 | 0.01 | 0.3 | 0.02 | — |
Stress Corrosion Cracking
| grade | Boiling 42% MgCI2 | Wick Test | Boiling 25% NaCl |
| 2205 | F | P | P |
| 254 SMO® | F | P | P |
| Type 316L | F | F | F |
| Type 317L | F | F | F |
| Alloy 904L | F | F or P | F or P |
| Alloy 20 | F | P | P |
Average chemical composition (weight %)
| C | Cr | In | Mo | N | Others |
| 0.020 | 22.1 | 5.6 | 3.1 | 0.18 | S=0.001 |
| PREN = [Cr%] = 3.3 [Mo%] = 16 [N%] ≥ 34 |
Mechanical properties Mechanical properties at room temperature
| ASTM A 240 | average value | |
| Yield Strength (0.2%), ksi | 65 minimum | 74 |
| Tensile Strength , ksi | 90 minimum | 105 |
| Elongation , % | 25 minimum | 30 |
| Hardness HB | 293 max | 256 |
Tensile properties at high temperature
| temperature F | 122 | 212 | 392 | 572 |
| Yield Strength (0.2%), ksi | 60 | 52 | 45 | 41 |
| Tensile Strength , ksi | 96 | 90 | 83 | 81 |
Physical Properties
physical properties
| temperature °F | 68 | 212 | 392 | 572 | |
| density | lb/in3 | 0.278 | — | — | — |
| Elastic Modulus | psi x 106 | 27.6 | 26.1 | 25.4 | 24.9 |
| Linear Expansion (681 4F-T) | 10-6/°F | — | 7.5 | 7.8 | 8.1 |
| Thermal Conductivity | Btu/h ft. °F | 8.7 | 9.2 | 9.8 | 10.4 |
| Heat capacity | Btu/lb/°F | 0.112 | 0.119 | 0.127 | 0.134 |
| Resistivity | in x 10-6 | 33.5 | 35.4 | 37.4 | 39.4 |
The chemical composition of structure 2205 is 1900°/1922°F (1040°/1080°C) solution annealed to obtain the ideal microstructure of 50 α / 50 γ . Heat treatment at temperatures above 2000°F may result in an increase in ferrite content. Like other duplex stainless steels , 2205 duplex stainless steel is susceptible to intermetallic precipitation. The intermetallic phase precipitates between 1300°F and 1800°F , with the fastest precipitation at 1600°F. Therefore, we need to test 2205 to ensure that there is no intermetallic phase, and the test refers to ASTM A 923.
Processing Hot Forming We recommend forming at temperatures below 600°F as much as possible. During the hot forming process, the entire workpiece should be heated as a whole and should be done in the temperature range of 1750°F to 2250°F, where 2205 duplex stainless steel is very soft. If the temperature is too high, 2205 duplex stainless steel is prone to hot tearing. Below this temperature, austenite will fracture. Below 1700°F, intermetallic phases form rapidly due to the effects of temperature and deformation. Immediately after hot forming, they should be solution annealed at a minimum temperature of 1900°F and quenched to restore phase balance, toughness and corrosion resistance. We do not recommend stress relief, but if necessary, the material should be solution annealed at a minimum temperature of 1900°F, then rapidly cooled and water quenched.
Cold-formed 2205 duplex stainless steel can be cut and cold-formed. However, due to the high strength and hardness of 2205 duplex stainless steel, it needs to be cold formed more than austenitic steel, and because of its high strength, the springback factor should be fully considered.
Heat treated 2205 duplex stainless steel should be annealed at a minimum temperature of 1900°F, then rapidly cooled and water quenched. This treatment is used for solution annealing and stress relief. Stress-relief treatments performed at temperatures below 1900°F tend to result in the precipitation of detrimental metallic or non-metallic phases.
Machinability On high-speed machines , the feed rates and cutting speeds of 2205 duplex stainless steel are the same as those of 316L. With carbonized knives, the cutting speed is reduced by approximately 20% compared to the 316L, where the performance of the machine and its components plays a key role.
The weldability of welding 2205 duplex stainless steel is very good. The performance to be achieved by 2205 duplex stainless steel is that the weld metal and thermally modified parts still maintain the same corrosion resistance, strength and toughness as the base metal. The welding of 2205 is not difficult, but its welding procedure needs to be designed so that after welding, a good phase balance can be maintained and the precipitation of harmful metal phases or non-metal phases can be avoided. The 2205 can be welded in the following equipment: GTAW (TIG); GMAW (MIG); SMAW (“stick” electrode); SAW; FCW; and PAW.