Duplex steel products

The so-called duplex stainless steel is a stainless steel with half of the ferrite phase and the austenite phase in its solid quenching structure, and the content of the minimum phase should reach 30%. Duplex stainless steel is formed by increasing Cr content or adding other ferrite elements on the basis of 18-8 austenitic stainless steel, which not only has austenite and ferrite bidirectional structure, but also saves Ni alloy. Due to the characteristics of duplex stainless steel two-phase structure, through the correct control of chemical composition and heat treatment process, duplex stainless steel can have the advantages of ferritic stainless steel and austenitic stainless steel. Duplex stainless steel reduces the brittleness of high Cr ferrite and the tendency of crystal growth due to the presence of austenite, and maintains excellent toughness and welding performance, while the presence of ferrite improves the yield strength of austenite, the ability to resist intergranular corrosion and the ability to resist chloride stress corrosion.


Advantages of duplex stainless steel

Compared with austenitic stainless steel, the advantages of duplex stainless steel are as follows:

First, the yield strength is more than twice as high as that of ordinary austenitic stainless steel, and it has sufficient plastic toughness for forming. The wall thickness of the storage or pressure vessel made of duplex stainless steel is reduced by 30 to 50% compared with that of ordinary austenite, which is beneficial to reduce the cost.

Second, it has excellent resistance to stress corrosion cracking. Even the duplex stainless steel with the lowest alloy content has higher resistance to stress corrosion cracking than austenitic stainless steel, especially in the environment containing chloride ions. Stress corrosion is a prominent problem that is difficult to solve for ordinary austenitic stainless steels.

Third, the corrosion resistance of 2205 duplex stainless steel, which is the most common 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 alloy austenitic stainless steel or even corrosion resistant alloy in some media.

Fourth, it has good local corrosion resistance. Compared with austenitic stainless steel with equivalent gold content, duplex stainless steel has better wear resistance and fatigue corrosion resistance than austenitic stainless steel.

Fifth, the linear expansion coefficient is lower than that of austenitic stainless steel, and it is close to carbon steel. It is suitable for connection with carbon steel, which has important engineering significance, such as the production of composite plates or linings.

Sixth, no matter under dynamic or static load conditions, duplex stainless steel has higher energy absorption capacity than austenitic stainless steel, which has practical application value for structural parts to cope with sudden accidents such as collisions and explosions.


Dual phase steel material grade

S31803 Duplex S32750 Duplex Super Duplex S32760