Product Name:

ASTM A240/A240M--01 duplex stainless steel 2205 alloy (UNS S32205 S31803)

Product Type: 

Pipe, Plate, Tube, Sheet, Bar, Coil, Pipe Fitting etc.

Introduction of SAF duplex 2205 stainless steel

SAF duplex 2205 stainless steel (UNS S32205, formerly known as UNS S31803, usually referred to as "alloy 2205") has a mixed microstructure of austenite and ferrite and is a two-phase alloy based on the Fe-Cr-Ni series. Alloy 2205 material has lower nickel and molybdenum content than austenitic stainless steel and has similar corrosion resistance. Due to the relatively high prices of nickel and molybdenum, duplex stainless steel 2205 is generally regarded as a cost-effective alternative to austenitic stainless steel.

Compared with the conventional 300 series stainless steel (such as SS 304, SS 316, SS 301, SS 904L and 303, etc.), the special advantage of duplex 2205 stainless steel is its strength (about twice that of austenitic stainless steel) and excellent Resistance to chloride SCC and pitting corrosion. The high yield strength has sufficient pressure and load capacity, and thin-walled materials can be manufactured to greatly reduce weight.

Structure of Alloy 2205 Duplex Stainless Steel

The chemical composition of 2205 can obtain the ideal microstructure 50 α / 50 γ after 1900°/1922°F (1040°/1080°C) solution annealing treatment. If the heat treatment temperature is higher than 2000°F, it may cause an increase in the ferrite composition. Like other duplex stainless steels, 2205 alloy is susceptible to the precipitation of intermetallic phases. The intermetallic phase precipitates between 1300°F and 1800°F, and the precipitation rate is the fastest at 1600°F. Therefore, we need to test 2205 to ensure that there is no intermetallic phase. The test refers to ASTM A 923.

machining of Alloy 2205 Duplex Stainless Steel

Thermoforming

We recommend that the forming should be done 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 carried out in the temperature range of 1750°F to 2250°F. Alloy 2205 is very soft at this temperature. If the temperature is too high, 2205 alloy is prone to hot tearing. If it is lower than this temperature, austenite will fracture. Below 1700°F, the intermetallic phase will form quickly due to the influence of temperature and deformation. After the hot forming is completed, it should be solid-solution annealed at a minimum temperature of 1900°F and quenched to restore its phase balance, toughness and corrosion resistance. We do not recommend stress relief, but if you must do so, the material should be solid solution annealed at a minimum temperature of 1900°F, then quickly cooled and water quenched.

Cold forming

2205 alloy can be cut and cold formed. However, due to the high strength and hardness of 2205 alloy itself, it needs more cold forming than austenitic steel. It is also because of its high strength that the springback must be fully considered.

Heat treatment

Alloy 2205 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. If the stress relief treatment is performed at a temperature below 1900°F, it will easily lead to the precipitation of harmful metallic or non-metallic phases.

Machinability

On high-speed machine tools, the feed rate and cutting speed of 2205 alloy are the same as those of 316L. If a carbonized knife is used, the cutting speed is reduced by about 20% compared with 316L. The performance of the machine and its components plays a key role here.

Welding

The weldability of 2205 alloy is very good. The required performance of 2205 alloy is that the weld metal and thermally deteriorated parts still maintain the same corrosion resistance, strength and toughness as the base metal. The welding of 2205 is not difficult, but the welding procedure needs to be designed so that after welding, it can maintain a good phase balance and avoid the precipitation of harmful metal phases or non-metal phases. 2205 can be welded in the following equipment: GTAW (TIG); GMAW (MIG); SMAW ("stick" electrode); SAW; FCW; and PAW

Duplex 2205 Alloy  Features:

Compared with 316L and 317L austenitic stainless steel, duplex stainless steel 2205 alloy has superior performance in resistance to pitting corrosion and crevice corrosion. It has high corrosion resistance. Compared with austenite, it The coefficient of thermal expansion is lower and the thermal conductivity is higher.

Compared with austenitic stainless steel, duplex stainless steel 2205 alloy has twice its compressive strength. Compared with 316L and 317L, the designer can reduce its weight. Alloy 2205 is especially suitable for the temperature range of -50°F/+600°F. Under strict restrictions (especially for welded structures), it can also be used at lower temperatures.

Duplex 2205 Alloy Chemical Composition:

C≤0.030 Mn≤2.00 Si≤1.00 p≤0.030 S≤0.020 Cr 22.0～23.0 Ni 4.5～6.5 Mo3.0～3.5 N0.14～0.20 (austenite-ferrite type)

Performance supplement: 

main component: 22Cr-5.3Ni-3.2Mo-0.16N; national standards: NAS 329J3L, UNS S32205/S31803, DIN/EN 1.4462, ASTM A240, ASME SA-240; mechanical properties: tensile strength: σb≥ 640Mpa; Elongation: δ≥25%; Typical working conditions: 20% dilute sulfuric acid, below 60℃, annual corrosion rate <0.1mm; Matching welding wire: ER2209.

1.  Chemical composition (JIS G 4305-005) (wt%)

2. Performance (JIS G 4305-2005)

3. Physical properties

Duplex 2205 Stainless Steel Alloy Application

Pressure vessels, high-pressure storage tanks, high-pressure pipes, heat exchangers (chemical processing industry).

Oil and gas pipelines, heat exchanger fittings.

Sewage treatment system.

Pulp and paper industry classifiers, bleaching equipment, storage and processing systems.

Rotary shafts, press rolls, blades, impellers, etc. under high-strength and corrosion-resistant environments.

Cargo boxes of ships or trucks

Food processing equipment