Stainless steel grade introduction: SUS 329J3L (2205)

SUS329J3L stainless steel, chemical composition and performance are similar to AISI 2205.

1. Overview

Duplex stainless steel containing a large amount of corrosion resistance strengthening elements such as Cr, Mo, N, and austenite and ferrite.

2. Features

1) The resistance to salt corrosion, pressure corrosion cracking (SCC), pitting corrosion, crevice corrosion, abrasion and erosion is very excellent; compared with 316L and 317L

austenitic stainless steel, 2205 steel is more resistant to corrosion damage The performance of cracks is superior, it has high corrosion resistance;

2) Compared with general austenitic stainless steel, the thermal expansion coefficient is lower, and the thermal conductivity is higher;

3) High strength, compared with austenitic stainless steel, Its compressive strength is twice that;

4) Improve the life of chemical and seawater equipment, and improve the economy of environmental protection equipment;

5) This alloy is especially suitable for the temperature range of -50¡ãF/+600¡ãF, in strict Under limited circumstances (especially for welded structures), it can also be used at lower temperatures.

3. Scope of application:

Pressure vessels, high-pressure storage tanks, high-pressure pipelines, heat exchangers (chemical processing industry), oil and gas pipelines, heat exchanger fittings, sewage treatment systems, pulp and paper industry classifiers, bleaching equipment, storage and treatment systems, Rotary shafts, press rolls, blades, impellers, etc. under high-strength corrosion-resistant environments, cargo boxes of ships or trucks, food processing equipment, seawater environment equipment, etc.

4. Chemical composition (JIS G 4305-2005) (wt%)

5. Performance (JIS G 4305-2005)

6. Physical performance

7. Heat treatment

Solution treatment: 950~11000C, quenching. Generally, the ratio of ferrite and austenite is controlled at about 50%, and generally the content of the least phase may reach 30%.

8. Use state

annealing and solid solution state: No. 1, 2D, 2B and other surface treatment states.

9. The difference between other steel grades.

Due to the characteristics of two-phase structure, through correct control of chemical composition and heat treatment process, it has the advantages of both ferritic stainless steel and austenitic stainless steel.

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. The wall thickness of storage tanks or pressure vessels made of duplex stainless steel is 30-50% less than that of commonly used austenite, which is beneficial to reduce costs;

2) It has excellent resistance to stress corrosion cracking, even the lowest alloy content Duplex stainless steels also have higher resistance to stress corrosion cracking than austenitic stainless steels, especially in environments containing chloride ions. Stress corrosion is a prominent problem that ordinary austenitic stainless steel is difficult to solve;

3) The 2205 duplex stainless steel, which is most commonly used in many media, has better corrosion resistance than ordinary 316L austenitic stainless steel, while super duplex stainless steel has extremely high corrosion resistance. In some mediums, such as acetic acid, formic acid, etc., it can even replace high-alloy austenitic stainless steels and even corrosion-resistant alloys.

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) Linear expansion than austenitic stainless steel Low coefficient, close to carbon steel, suitable for connection with carbon steel, with important engineering significance, such as the production of composite plates or linings, etc.;

6) No matter under dynamic or static load conditions, it has higher energy than austenitic stainless steel Absorptive capacity, which is suitable for structural parts to cope with sudden accidents such as collisions and explosions. Duplex stainless steel has obvious advantages and has practical application value.

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

1) The universality and versatility of application are not as good as austenitic stainless steel, for example, its service temperature must be controlled below 250 degrees Celsius;

2) Its plastic toughness is more austenitic Stainless steel is low, cold and hot processing technology and forming performance are not as good as austenitic stainless steel;

3) There is a medium temperature brittle zone, the heat treatment and welding process system needs to be strictly controlled to avoid the appearance of harmful phases and damage performance.

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

1) Comprehensive mechanical properties are better than ferritic stainless steel, especially plastic toughness, not as sensitive to brittleness as ferritic stainless steel;

2) In addition to stress corrosion resistance In addition, other local corrosion resistance performance is better than ferritic stainless steel;

3) Cold working process performance and cold forming performance are much better than ferritic stainless steel;

4) Welding performance is also much better than ferritic stainless steel, generally not required before welding Preheating, no need for heat treatment after welding;

5) The application range is wider than ferritic stainless steel.

Compared with ferritic stainless steel, the disadvantages of duplex stainless steel are as follows:

1) The content of alloying elements is high and the price is relatively high. Generally, ferrite does not contain nickel.