The so-called duplex stainless steel has half of the fe […]
The so-called duplex stainless steel has half of the ferrite phase and austenite phase in its solid-quenched structure, and generally, the minimum phase content needs to reach 30%.
Due to the characteristics of the two-phase structure, Duplex Stainless Steel has the advantages of both ferritic stainless steel and austenitic stainless steel through correct control of chemical composition and heat-treatment process. Today we mainly discuss the advantages of austenite and ferrite.
Compared with austenitic stainless steel, the advantages of duplex stainless steel are as follows:
(1) The yield strength is more than twice that of ordinary austenitic stainless steel, and it has sufficient plastic toughness for forming.
(2) It has excellent resistance to stress corrosion cracking. Even the duplex stainless steel with the lowest alloy content has a higher resistance to stress corrosion cracking than austenitic stainless steel, especially in an environment containing chloride ions.
(3) The corrosion resistance of 2205 duplex stainless steel, which is most commonly used in many media, is better than that of ordinary 316L austenitic stainless steel, while super duplex stainless steel has extremely high corrosion resistance and can even replace high corrosion resistance in some media. Alloy austenitic stainless steel, even corrosion-resistant alloy.
(4) It has good local corrosion resistance. Compared with austenitic stainless steel with the same alloy content, its wear corrosion resistance and fatigue corrosion resistance are better than 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 connection with carbon steel and has important engineering significance.
(6) Whether under dynamic or static load conditions, it has higher energy absorption capacity than austenitic stainless steel. When dealing with unexpected accidents such as collisions and explosions, duplex stainless steel has obvious advantages and has practical application value.
Compared with duplex stainless steel, the advantages of austenitic stainless steel are as follows:
(1) The universality and multi-faceted austenitic stainless steels are stronger than duplex stainless steels.
(2) Its plastic toughness is lower than that of austenitic stainless steel, and it is not as good as austenitic stainless steel in cold and hot processing technology and forming performance.
(3) There is a medium-temperature brittle zone, and the processing system of heat treatment and welding needs to be strictly controlled to avoid the appearance of harmful phases and damage performance.
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