316L stainless steel welded pipe and 2205 duplex stainless steel welded pipe are two different materials. What is the difference between them? 2205 duplex stainless steel pipe has a history of 80 years. Nitrogen is added to the material of 2205 stainless steel pipe to improve local corrosion resistance. Its solid solution structure contains about half of the ferrite and austenite phases, and generally the least compatible content It also needs to reach 30%, so it has the performance characteristics of ferritic and austenitic stainless steel.
Compared with austenitic 316L steel pipe, 2205 duplex stainless steel pipe has the following advantages.
1. The yield strength is more than twice that of 316L austenitic stainless steel, and it has sufficient plastic toughness for forming. The wall thickness of pressure vessel made of 2205 stainless steel pipe is 30-50% less than that of 316L stainless steel pipe, which is beneficial to reduce costs.
2. 2205 steel pipe has excellent resistance to stress corrosion cracking, especially in the marine environment containing chloride ions, stress corrosion is difficult to solve the outstanding problem of austenitic stainless steel.
3. The general corrosion resistance of 2205 duplex steel used in many media is due to ordinary 316L stainless steel, and super duplex stainless steel has extremely high corrosion resistance. For example, it can even replace high-alloy austenitic stainless steel in acetic acid, formic acid, etc. Tubes, and even corrosion-resistant alloys.
4. It has good local corrosion resistance. Compared with austenitic stainless steel with the same alloy content, in view of the high strength and good corrosion resistance of 2205 duplex stainless steel, its wear corrosion resistance and corrosion fatigue performance are due to general 316L austenitic stainless steel.
5. The coefficient of linear expansion is lower than that of austenitic stainless steel, which is close to that of carbon steel. It is suitable for carbon steel connection and has important engineering significance.
6. No matter under the conditions of dynamic or static load, it has higher energy absorption capacity than 316L stainless steel pipe. This has obvious practical application value for structural parts or pipelines to deal with sudden collisions, explosions, etc., the advantages of 2205 stainless steel pipe.
Compared with 316L stainless steel pipe, the disadvantages of 2205 stainless steel pipe are as follows;
1. The universality and versatility of application are not as good as 316L austenitic stainless steel. For example, for long-term application, the temperature of the medium used must be controlled below 250 degrees.
2. Its plastic toughness is lower than that of 316L stainless steel, and its cold and hot processing technology and forming performance are poor.
3. There is medium temperature brittleness, and it is necessary to strictly control the heat treatment and welding process system to avoid harmful interactions and damage performance.
The main reason for the disadvantage of duplex stainless steel compared with austenitic stainless steel is that duplex stainless steel contains a large amount of ferrite structure.
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