What is 2205 duplex stainless steel

2205 duplex stainless steel is mainly composed of 22% Cr, 3% molybdenum and 5-6% Ni nitrogen composition. It has high strength, better impact toughness and better overall and local resistance to stress corrosion.

 

General properties of stainless steel

 

Compared with 316L and 317L austenitic stainless steel, 2205 duplex stainless steel in the anti-pitting corrosion and corrosion of the better performance, it has a high corrosion resistance, compared with the austenite, its thermal expansion coefficient is lower , Higher thermal conductivity.

2205 yield strength is twice the austenitic stainless steel, this feature allows designers to reduce the weight of the design of the product, so that this stainless steel than 316, 317L stainless steel more price advantage.

This stainless steel is particularly suitable for use in the temperature range of -50 ° F / + 600 ° F. Out of range applications should be used with caution, especially when applied to welded structures.

 

The applications of stainless steel

 

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

Oil and gas pipeline, heat exchanger pipe fittings.

Sewage treatment system.

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

High-strength corrosion-resistant environment of the rotary shaft, press roll, blades, impeller and so on.

Food processing equipment.

 

Corrosion resistance of stainless steel

 

Uniform corrosion

 

Due to the Cr content (22%), molybdenum (3%) and nitrogen content (0.18%), the corrosion resistance of 2205 duplex stainless steel is better than 317L and 316L stainless steel in most environments.

 

Partial corrosion resistance

 

2205 in the Cr, molybdenum and nitrogen content in the oxidizing and acidic solution, the point of corrosion and corrosion has a strong resistance.

 

The corrosion curve in a sulfuric acid solution containing 2000 ppm of chloride was 4 mpy (0.1 mm / yr)

 

Anti-stress corrosion

 

The dual phase microstructure of stainless steel improves the corrosion resistance of stainless steel. At a particular temperature, oxygen, tension and chloride in the presence of austenitic stainless steel will occur chloride stress corrosion.

 

Corrosion resistance

 

2205 duplex stainless steel has a very good anti-corrosion fatigue strength, especially suitable for processing equipment, effectively avoid susceptible to corrosion environment and loading cycle.

The critical temperature of the etching in 1M NaCl was measured using an AvestaPolarit etch cell

The critical temperature of corrosion in the gap of 10% FeCl3.6H2O

 

Uniform corrosion in wet treated phosphoric acid

Uniform corrosion of stainless steel

 

Resistance to stress cracking

(P = via F = not passed)

 

The chemical composition of stainless steel

Average (% by weight)

 

Mechanical properties of stainless steel

Mechanical properties at room temperature

Mechanical properties of stainless steel at room temperature

 

Mechanical properties at high temperature

Mechanical properties of stainless steel at high temperature

 

Physical properties of stainless steel

Physical properties of stainless steel

 

structure

 

The chemical composition of 2205 achieves the ideal microstructure 50 α / 50 γ after annealing at 1900 ° / 1922 ° F (1040 ° / 1080 ° C).

If the temperature of the heat treatment is higher than 2000 ° F, the composition of the ferrite component may be increased.

Like other duplex stainless steel, 2205 duplex stainless steel is susceptible to intermetallic precipitation. The intermetallic phase precipitates between 1300 ° F and 1800 ° F, and the precipitation rate is the fastest at 1600 ° F.

 

The processing of stainless steel

 

Thermoforming

 

We recommend that the forming should be carried out at temperatures below 600 ° F. During the thermoforming process, the entire workpiece should be heated as a whole and should be in the temperature range of 1750 ° F to 2250 ° F. 2205 Duplex stainless steel is very soft at this temperature. If the temperature is too high, 2205 duplex stainless steel is easy to tear. If below this temperature, austenite will break. Below 1700 ° F, the intermetallic phase is quickly formed due to temperature and deformation. After the thermoforming is carried out, it should be immediately 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 this is necessary, the material should be annealed at a minimum temperature of 1900 ° F and then rapidly cooled for water quenching.

 

Cold forming

 

2205 duplex stainless steel can be cut and cold formed. However, due to its own high strength and hardness of 2205 duplex stainless steel, it is more cold than the austenitic steel, but also because of its high strength, to fully take into account the rebound factor.

 

The heat treatment of stainless steel

 

2205 Duplex stainless steel should be annealed at a minimum temperature of 1900 ° F and then rapidly cooled for water quenching. This treatment is applied to solid solution annealing and stress relief. Stress relief is carried out at temperatures below 1900 ° F, which can easily lead to the precipitation of harmful metal or nonmetallic phases.

 

Mechanical machinability

 

In the high-speed machine, 2205 duplex stainless steel feed rate and cutting speed and 316L is the same. If the use of carbonized knife, cutting speed and 316L compared to about 20% lower, the performance of machinery and equipment and its components play a key role in this.

Source: Yaang Pipe Industry Co., Limited (www.yaang.com)

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