Duplex stainless steel 2205 is a ferritic-austenitic duplex stainless steel. Through precise chemical composition balance and heat treatment processes, it combines the strength of ferritic stainless steel with the corrosion resistance advantages of austenitic stainless steel. Due to its excellent comprehensive performance, it has been widely used in multiple industrial fields.
Chemical composition and microstructure
The typical chemical composition (by mass fraction) of 2205 duplex stainless steel is approximately as follows: 22% chromium (Cr), 5.5% nickel (Ni), 3% molybdenum (Mo), and 0.17% nitrogen (N), with the rest being iron (Fe) and a small amount of common elements. The synergy of these elements ensures its outstanding performance.
- Chromium and molybdenum: They offer excellent resistance to pitting and crevice corrosion.
- Nitrogen: It not only significantly enhances corrosion resistance, especially pitting resistance, but also effectively stabilizes the austenite phase, promotes its formation, and increases the strength of the material.
The "duplex" in its name is directly derived from the microstructure of its ferrite (α phase) and austenite (γ phase), each accounting for approximately 50%. This dual-phase structure is the fundamental reason for many of its excellent properties.
Mechanical and physical properties
The most prominent mechanical feature of 2205 duplex stainless steel is its high strength:
- The tensile strength (σb) is ≥ 620 MPa, and some data show that it can even reach ≥795 MPa
- The yield strength (σ0.2) is ≥ 450 MPa, with the highest reported value being ≥550 MPa
- Elongation (δ) ≥ 25%, some data show ≥15%
- Hardness ≤ 310 HB
Its yield strength is about twice that of common austenitic stainless steels such as 304L or 316L. This characteristic enables the wall thickness to be reduced and the structural weight to be decreased when designing and manufacturing equipment that bears the same load, thus making it more cost-effective.
In terms of physical properties, its density is approximately 7.98 g/cm³. Compared with austenitic stainless steel, it has a lower coefficient of thermal expansion and higher thermal conductivity, which makes it have less thermal stress and better dimensional stability under thermal cycling conditions.
Corrosion resistance performance
The corrosion resistance of 2205 duplex stainless steel is comprehensively superior to that of 316L and 317L austenitic stainless steel, mainly reflected in:
Outstanding resistance to stress corrosion cracking: The dual-phase structure can effectively prevent crack propagation, making it perform exceptionally well in environments containing chlorides.
Outstanding resistance to pitting and crevice corrosion: The high content of chromium, molybdenum and nitrogen makes its pitting resistance equivalent value relatively high, enabling it to withstand more harsh environments.
Excellent uniform corrosion resistance: It has good resistance to uniform corrosion in various acidic and oxidizing media.
Key points of processing and manufacturing
Heat treatment: Correct solution treatment is crucial, typically carried out between 1020 ° C and 1100 ° C, followed by rapid water cooling. It is necessary to avoid staying in the temperature range of 425-980℃ (especially 650-950℃) for a long time to prevent the precipitation of brittle phases.
Welding: 2205 has good weldability. It is recommended to use ER2209 welding wire or E2209 electrode, and the matching welding materials. When welding, the heat input should be controlled to avoid being too high. Generally, preheating and post-heating are not carried out.
Cold forming: Due to its high strength, greater processing force is required, and a larger springback amount must be taken into consideration.
Hot forming: The heating temperature is recommended to be within the range of 1750°F to 2250°F (approximately 954 ° C -1232 ° C). After completion, immediate solution treatment and rapid cooling are required.
Main application fields
Oil and gas industry: Offshore platform equipment, process pipelines, oil and gas transportation pipelines.
Chemical process industry: pressure vessels, storage tanks, heat exchangers, reactors.
Marine and seawater environment: high-pressure pipelines for seawater desalination plants, Marine components, and structural parts for offshore platforms.
Energy and environmental protection: Flue gas desulfurization systems for power plants, industrial water treatment and sewage treatment systems.
Others: Cooking equipment for the pulp and paper industry, pharmaceutical equipment for the food industry, etc.
Conclusion
2205 duplex stainless steel , with its high strength and outstanding corrosion resistance, especially its advantage in resisting stress corrosion cracking, has become an ideal material choice for many harsh working conditions. Although it has some special requirements in processing and manufacturing, its outstanding comprehensive performance has enabled it to occupy an irreplaceable position in important industrial fields such as petrochemicals, Marine and energy.
Post time: Nov-25-2025
