What is duplex stainless steel? What are the characteristics of duplex stainless steel?

What is duplex stainless steel? What are the characteristics of duplex stainless steel?

Definition of duplex stainless steel

Under normal circumstances, the ferritic content in austenitic stainless steel is 50%-60%, while the ferritic content in duplex stainless steel is higher, up to more than 75%.

Because austenitic stainless steel and ferritic stainless steel have good corrosion resistance, and there is a large composition difference between the two, the two kinds of stainless steel are not one material, but two materials with different properties.

Duplex stainless steel is austenitic and ferrite two-phase coexistence of stainless steel, with good corrosion resistance, high temperature strength and plasticity, toughness and workability.

Because austenitic stainless steel has good mechanical properties at room temperature, it is often used to make structural parts requiring high strength; The mechanical properties of ferritic stainless steel are poor at room temperature, and it is generally used for making structural parts requiring good high and low temperature properties.

Two, the composition and performance of duplex stainless steel

The composition (mass fraction) of duplex stainless steel is similar to that of ordinary austenitic stainless steel, but because of the different proportion of the two phases, it has the following characteristics:

1. Excellent intergranular corrosion resistance;

2, with good welding performance, can be welding below 600℃;

3, has good resistance to stress corrosion cracking, in pitting corrosion and crevice corrosion and other environments its corrosion resistance is better than austenitic stainless steel;

4, with good high temperature oxidation resistance.

Duplex stainless steel due to the different proportion of two phases, there are significant differences in performance, so duplex stainless steel is more superior than ordinary austenitic stainless steel. Stainless steel with different properties can be obtained by adjusting the two-phase ratio in production.