Bobina de acero inoxidable AISI 2205 y SUS329J3L

2205 Duplex Stainless Steel (referred to as DSS)

Introduction:

 2205 Duplex Stainless Steel (referred to as DSS)refers to ferrite and austenite each accounting for about 50%, generally the content of less phase also needs to reach at least 30% stainless steel. In the case of low C content, Cr content is 18%~28%, Ni content is 3%~10%. Some steels also contain alloying elements such as Mo, Cu, Nb, Ti, and N.

This type of steel has the characteristics of austenitic and ferritic stainless steel. Compared with ferrite, it has higher plasticity and toughness, no room temperature brittleness, and has significantly improved intergranular corrosion resistance and welding performance, while maintaining iron. The 475°C brittleness and high thermal conductivity of plain stainless steel are characterized by superplasticity. Compared with austenitic stainless steel, the strength is high and the resistance to intergranular corrosion and chloride stress corrosion is significantly improved. Duplex stainless steel has excellent pitting corrosion resistance and is also a nickel-saving stainless steel.

Performance characteristics:

Due to the characteristics of the two-phase structure, through the correct control of the chemical composition and heat treatment process, the duplex stainless steel has the advantages of ferritic stainless steel and austenitic stainless steel. It combines the excellent toughness and weldability of austenitic stainless steel with iron The higher strength and resistance of plain stainless steel

The combination of chloride stress corrosion resistance, it is these superior properties that make duplex stainless steel as a weldable structural material. It has become a parallel with martensitic, austenitic and ferritic stainless steels since the 1980s. Steel. Duplex stainless steel has the following performance characteristics:

(1) The duplex stainless steel containing molybdenum has good resistance to chloride stress corrosion under low stress. Generally, 18-8 austenitic stainless steel is prone to stress corrosion cracking in neutral chloride solutions above 60°C. Heat exchangers and evaporators made of such stainless steel in trace chloride and hydrogen sulfide industrial media All have a tendency to produce stress corrosion cracking, but duplex stainless steel has good resistance.

(2) Molybdenum-containing duplex stainless steel has good pitting corrosion resistance. With the same pitting corrosion resistance equivalent value (PRE=Cr%+3.3Mo%+16N%), the critical pitting potential of duplex stainless steel is similar to that of austenitic stainless steel. The corrosion resistance of duplex stainless steel and austenitic stainless steel is equivalent to AISI 316L. The chromium corrosion resistance and crevice corrosion resistance of 25% Cr, especially nitrogen-containing high-chromium duplex stainless steel exceeds AISI 316L.

(3) Has good corrosion resistance fatigue and wear corrosion performance. Under the condition of certain corrosive media, it is suitable for making pumps, valves and other power equipment.

(4) Good comprehensive mechanical properties. It has higher strength and fatigue strength, and the yield strength is twice that of 18-8 austenitic stainless steel. The elongation in solid solution reaches 25%, and the toughness value AK (V-notch) is above 100J.

(5) The weldability is good, the tendency of hot cracking is small, generally no preheating is required before welding, and no heat treatment is required after welding. It can be welded with different types of 18-8 austenitic stainless steel or carbon steel.

(6) The temperature range of duplex stainless steel containing low chromium (18%Cr) is wider than that of 18-8 austenitic stainless steel, and the resistance is small. It can be rolled directly to produce steel plates without forging. Duplex stainless steel with high chromium (25% Cr) is slightly more difficult to heat than austenitic stainless steel, and can produce products such as plates, tubes and wires.

(7) The work hardening effect is greater than that of 18-8 austenitic stainless steel during cold working. In the initial stage of deformation of the tube and plate, large stress needs to be applied to deform.

(8) Compared with austenitic stainless steel, the coefficient of thermal conductivity is large and the coefficient of linear expansion is small, which is suitable for the lining of equipment and the production of composite plates. It is also suitable for making the core of heat exchanger, the heat exchange efficiency is higher than that of austenitic stainless steel.

(9) There are still various brittle tendencies of high chromium ferritic stainless steel, which should not be used in working conditions higher than 300°C. The lower the chromium content in duplex stainless steel, the less harmful the brittle phase such as σ.

use:

Used in heat exchangers, cold showers and devices such as oil refining, chemical fertilizers, paper making, petroleum, chemical industry, etc.

Structure and type:

Duplex stainless steel has the austenite + ferrite dual phase structure, and the content of the two phase structures is basically the same, so it has the characteristics of austenitic stainless steel and ferritic stainless steel. The yield strength can reach 400Mpa ~ 550MPa, which is twice that of ordinary austenitic stainless steel. Compared with ferritic stainless steels, duplex stainless steels have high toughness, low brittle transition temperature, and significantly improved intergranular corrosion resistance and welding performance; while retaining some of the characteristics of ferritic stainless steels, such as 475℃ brittleness, heat High conductivity, small linear expansion coefficient, superplasticity and magnetic properties. Compared with austenitic stainless steels, duplex stainless steels have high strength, especially yield strength is significantly improved, and pitting corrosion resistance, stress corrosion resistance, corrosion fatigue resistance and other properties have also been significantly improved.

　　Duplex stainless steel is classified according to its chemical composition and can be divided into four categories: Cr18, Cr23 (without Mo), Cr22 and Cr25. For Cr25 duplex stainless steel, it can be divided into ordinary type and super duplex stainless steel, of which Cr22 type and Cr25 type are mostly used. The duplex stainless steels used in my country are mostly produced in Sweden. The specific grades are: 3RE60 (Cr18 type), SAF2304 (Cr23 type), SAF2205 (Cr22 type), SAF2507 (Cr25 type).