When it comes to duplex steel, many people refer to the 2507 and 2205 types. These two steels have a wide range of applications, such as the chemical industry, oil, and gas, marine engineering, etc. Although the two sheets of steel are similar in name, there are obvious differences in their chemical composition, physical properties, corrosion resistance, and applicable scenarios. This article will explore the characteristics of duplex 2507 vs 2205, analyze the differences between them, and how choose the appropriate steel for practical applications.
Duplex stainless steel is called “duplex” because its metallographic microstructure consists of two types of stainless steel grains, ferrite, and austenite.
We commonly use duplex 2507 vs 2205 stainless steel, so what is the difference between them, and which grade of duplex stainless steel should our industry choose?
What is 2205 Duplex Steel?
Duplex stainless steel 2205 is a composite stainless steel composed of 21% chromium, 2.5% chromium, and 4.5% nickel-nitrogen alloy. It has high strength, good impact toughness, and good overall and local stress corrosion resistance.
What is 2507 Duplex Steel?
2507 is a ferrite-austenite two-phase super duplex stainless steel, which has better resistance to pitting corrosion, crevice corrosion, and uniform corrosion. Has high compressive strength, impact strength, low thermal expansion coefficient, and high thermal conductivity.
Duplex 2507 vs 2205 Data Sheet
Chemical Composition
| Duplex Steel Grade | C | Si | Mn | Cr | Ni | S | P | Mo | N |
|---|---|---|---|---|---|---|---|---|---|
| 2205 (S32205) | 0.030 | 1.00 | 2.00 | 22.0-23.0 | 4.5-6.5 | 0.020 | 0.030 | 3.0-3.5 | 014-0.20 |
| 2507 (S32750) | 0.030 | 0.80 | 1.20 | 24.0-26.0 | 6.0-8.0 | 0.020 | 0.035 | 3.0-5.0 | 0.24-0.32 |
Mechanical Performance
| Duplex Steel Grade | Tensile Strength Rm(MPa) | Yield Strength RPO.2N/MPa | Elongation 85(%) |
|---|---|---|---|
| 2205 (S32205) | ≥620 | ≥450 | ≥25 |
| 2507 (S32750) | ≥800 | ≥550 | ≥25 |
Comparing Duplex 2507 vs 2205
There are obvious differences between duplex 2507 vs 2205 in terms of chemical composition, physical properties, corrosion resistance, and applicable scenarios.
Chemical Composition Comparison:
Duplex steel 2507 contains higher molybdenum, chromium, and nitrogen content, with about twice the molybdenum content of duplex steel 2205. This difference in chemical composition allows 2507 to have higher corrosion resistance and higher strength.
Physical Performance Comparison:
In terms of physical properties, duplex steel 2507 has higher yield strength, tensile strength, and impact toughness, and correspondingly, its elongation is lower. The physical properties of two-way steel 2205 are relatively balanced, with high strength and hardness, but also good ductility and toughness.
Corrosion Resistance Comparison:
Due to the difference in chemical composition, duplex steel 2507 is more resistant to corrosion than 2205, especially in environments containing chloride ions and acidic environments. Under the same conditions, 2507 is more resistant to corrosion, wear, pitting, and intergranular corrosion than 2205.
Applicable Scene Comparison:
Duplex steel 2507 is suitable for more severe conditions, such as applications in harsh environments such as high temperature, high pressure, acidic environment, and seawater. Whereas duplex steel 2205 is suitable for general industrial applications such as chemical, oil, and gas.
Overview:
In terms of a comprehensive evaluation, the strength, hardness, and corrosion resistance of duplex steel 2507 are better than 2205, but its cost is higher. Therefore, when choosing two-way steel, it should be selected according to the actual application requirements. If higher strength and corrosion resistance are required, and the budget is sufficient, you can choose 2507; if the budget is more limited, or the application scenario is not too demanding, you can choose 2205.
Features of Duplex Steel 2507 VS 2205
Features of 2507 Duplex Stainless Steel
Duplex Steel 2507 is a high-performance duplex stainless steel with the following characteristics:
Good corrosion resistance: duplex steel 2507 contains higher molybdenum, chromium, and nitrogen content, and this difference in chemical composition makes it perform better in chloride-containing and acidic environments. In seawater, acid solution, and other corrosive media, 2507 can resist corrosion and wear very well and has extremely strong resistance to pitting corrosion and intergranular corrosion.
High strength and hardness: 2507 super duplex stainless steel has higher yield strength, tensile strength, and hardness, mainly due to its higher chromium, molybdenum, and nitrogen content. These physical properties enable 2507 to maintain its structural stability and resistance to deformation under harsh conditions such as high temperature and high pressure.
Good toughness and ductility: Although 2507 super duplex stainless steel has high strength and hardness, it can still maintain a certain degree of toughness and ductility, thus alleviating the impact of its hardness and brittleness on processing and use to a certain extent. This characteristic allows 2507 to be used where both high strength and good toughness are required.
Wide range of application fields: 2507 duplex stainless steel is widely used in marine engineering, the chemical industry, oil and gas exploration, and other fields due to its excellent corrosion resistance, high strength, and hardness. For example, it can be used to produce offshore oil wells, subsea pipelines, petrochemical equipment, offshore platform structures, etc.
Higher cost: Compared with duplex steel 2205, duplex steel 2507 has a more complicated composition and production process, so its cost is higher. However, in the occasions of high performance and special requirements, the cost performance of 2507 is still very high.
Features of 2205 Duplex Stainless Steel
Duplex steel 2205 is a commonly used duplex stainless steel with the following characteristics:
Good corrosion resistance: 2205 duplex stainless steel contains a moderate amount of chromium, molybdenum, and nitrogen, which can perform well in environments with high acidity, alkalinity, and chloride content, especially in seawater containing chloride ions. corrosion performance. In addition, 2205 is resistant to stress corrosion cracking and intergranular corrosion.
Good toughness and ductility: 2205 duplex stainless steel has high plasticity and toughness and can maintain a certain degree of ductility at low and high temperatures, so it is suitable for various processing and forming processes, such as cold drawing, cold rolling, welding, etc.
High strength: Although 2205 duplex stainless steel is not as strong as duplex 2507 stainless steel, it still has high yield strength and tensile strength and is suitable for occasions that require higher strength.
Good comprehensive performance: The comprehensive performance of 2205 duplex stainless steel is good, not only has high corrosion resistance and strength but also has good processing performance and welding performance, so it is widely used in many fields.
Wide range of uses: Two-way steel 2205 can be used in the production of the chemical industry, marine engineering, submarine pipelines, oil and gas extraction equipment, food processing equipment, etc., and its application fields are very wide.
In conclusion, duplex 2205 stainless steel has good corrosion resistance, high strength, good processability, and wide application fields, and is a commonly used duplex stainless steel.
Application of Duplex 2507 vs 2205
2205 duplex steel Application field: Pressure vessels, high-pressure storage tanks, high-pressure pipelines, and heat exchangers (chemical processing industry). Oil and gas pipelines, heat exchanger fittings. sewage treatment system. Pulp and paper industry classifiers, bleaching plants, storage and handling systems. Rotary shafts, press rolls, blades, impellers, etc. in high-strength and corrosion-resistant environments. Cargo boxes for ships or trucks of food processing equipment
2507 duplex stainless steel application fields: used in the oil and natural gas industry; offshore Shibatian oil platform (heat exchanger tube, water treatment, and water supply system, fire protection system, water spray system, water stabilization system; petrochemical equipment; desalination (desalination) equipment ( and high-pressure pipes in equipment, seawater pipes); mechanical and structural components that require both high strength and high corrosion resistance; combustion (waste) gas purification equipment.
Type of Duplex Stainless Steel
Duplex stainless steels comprise a range of grades with different corrosion resistance properties depending on their alloy composition. This paper classifies modern duplex stainless steels into five categories based on their corrosion resistance:
1. Economical duplex stainless steel with no intentional addition of molybdenum, such as 2304;
2. Economical duplex stainless steel containing molybdenum, such as S32003;
3. Standard duplex stainless steel with a Cr content of about 22% and a Mo content of 3%, such as 2205, is the main grade, accounting for about 60% of the duplex stainless steel consumption;
4. Super duplex stainless steel with a Cr content of about 25% and a Mo content of 3%, with a PREN value of 40-45, such as 2507;
5. Super duplex stainless steel, Cr and Mo content is higher than super duplex stainless steel, PREN value is greater than 45, such as S32707
Advantages of 2205 and 2507 Duplex Stainless Steel
In recent years, in the duplex steel market, 2507 duplex stainless and 2205 duplex stainless steel have replaced ordinary stainless steel. Let’s take a look at what advantages they have to replacing other stainless steel.
1. Strength: The strength of duplex stainless steel is about twice that of ordinary austenitic or ferritic steel. They also have better ductility and toughness than ferritic steels. Due to its high yield strength, the use of duplex stainless steels can result in significant weight savings as thinner sections can be used. Weight reduction can be a significant advantage for applications such as pressure vessels, storage tanks, and structural applications.
2. Corrosion resistance: When comparing corrosion resistance, the composition of duplex stainless steel makes it different from conventional austenitic and ferritic stainless steel. Duplex stainless steels are less prone to stress corrosion cracking (SCC) than austenitic steels such as 304 and 316. Although there is no single measure of corrosion resistance, to grade different grades, the Pitting Resistance Equivalent Number (PREN) method is often used.
3. Ease of fabrication: Duplex stainless steels are generally easier to form under pressure than ferritic stainless steels. Although duplex stainless steels have 50% ferrite, the 50% austenite content makes them easier to manufacture than conventional stainless steels. Duplex stainless steels also exhibit better weldability on thicker sections than other ferritic and austenitic stainless steels.
4. Cost-effectiveness: Compared to the advantages listed above, which is price, duplex stainless steels are usually cheaper than conventional austenitic stainless steels. The price of duplex steel is generally more stable than that of ordinary stainless steel, which makes duplex steel more acceptable to customers after cost estimation.
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