General Properties of Duplex 2205 Stainless Steel Pipe

Duplex 2205 stainless steel is a duplex ferritic-austenitic alloy containing 22% chromium, 3% molybdenum, and 5-6% nickel. It is the most widely used grade of duplex stainless steel, offering twice the yield strength of standard austenitic grades. Known for its excellent fatigue strength, it provides outstanding resistance to stress corrosion cracking, crevice corrosion, pitting, erosion, and general corrosion, even in harsh environments.

Chemical Composition

Duplex 2205 stainless steel boasts a well-balanced chemical composition that includes:

• Chromium: 21-23%
• Molybdenum: 2.5-3.5%
• Nickel: 4.5-6.5%
• Nitrogen: 0.8-2.0%
• Manganese: <2%
• Silicon: <1%
• Phosphorus: <0.03%
• Sulfur: <0.02%
• Iron: Balance

The high chromium content in Duplex 2205 is a key factor in its excellent corrosion resistance. Chromium forms a passive layer on the steel surface, protecting it from oxidation and corrosion. Molybdenum and nitrogen further enhance this resistance, particularly against pitting and crevice corrosion, making Duplex 2205 a robust choice for challenging environments.

Mechanical Properties

Duplex 2205 stainless steel is renowned for its impressive mechanical properties:

• Yield strength: 448 MPa (65,000 psi) min
• Tensile strength: 621 MPa (90,000 psi) min
• Elongation at break: 25% min
• Reduction of area: 50% min
• Hardness: 31 max Rockwell C (HR C)

Compared to austenitic stainless steels, Duplex 2205 offers significantly higher yield and tensile strength. This makes it an excellent option for applications that demand both high strength and good corrosion resistance. Its mechanical properties ensure durability and reliability, even in the most demanding conditions.

PHYSICAL PROPERTIES

The physical properties of Duplex 2205 stainless steel are as follows:

• Density: 7.8 g/cm³
• Melting point: 1450°C (2642°F)
• Thermal expansion: 13.7 x 10^-6 K^-1 (7.6 x 10^-6 °F^-1)
• Thermal conductivity: 14.2 W/m-K (8.2 Btu/h-ft-°F)
• Specific heat capacity: 500 J/kg-K (0.12 Btu/lb-°F)
• Electrical resistivity: 80 x 10^-8 Ωm (50 x 10^-8 Ωin)

These properties contribute to the alloy’s excellent performance in various industrial applications, ensuring stability and efficiency under different thermal and mechanical conditions.

Heat Resistance

Duplex 2205 stainless steel exhibits good heat resistance, but it is not designed for high-temperature applications. The maximum recommended temperature for Duplex 2205 is 300°C (572°F). Beyond this temperature, the material may undergo precipitation, which can adversely affect its corrosion resistance and mechanical properties. Therefore, it is crucial to use Duplex 2205 within its specified temperature range to maintain its integrity and performance.

APPLICATIONS IN HIGH CHLORIDE ENVIRONMENTS

• Chemical processing, transport and storage – pressure vessels, tanks, piping, and heat exchangers
• Oil and gas exploration and processing equipment – piping, tubing, and heat exchangers
• Marine and other high chloride environments
• Effluent scrubbing systems
• Pulp and paper industry – digesters, bleaching equipment, and stock-handling systems
• Cargo tanks for ships and trucks
• Food processing equipment
• Biofuels plants

STANDARDS

• ASTM/ASME: A240 UNS S32205/S31803
• EURONORM: 1.4462 X2CrNiMoN 22.5.3
• AFNOR: Z3 CrNi 22.05 AZ
• DIN: W.Nr 1.4462

Good Corrosion Resistance

Duplex 2205 offers excellent resistance to corrosion due to its high chromium, molybdenum, and nitrogen content. It outperforms 316 and 316L stainless steels in most environments, especially in oxidizing and acidic solutions. Its resistance to pitting and crevice corrosion is outstanding, even in harsh chloride-containing environments. Additionally, it can withstand chloride stress corrosion cracking at temperatures up to 302°F (150°C). The ferritic structure also enhances its performance in caustic conditions.

Heat Resistance
Duplex 2205 provides good oxidation resistance at elevated temperatures. However, it may become brittle when exposed to temperatures above 572°F (300°C), even for short durations. Therefore, it is not recommended for use in applications exceeding this temperature.

Welding Characteristics
Duplex 2205 demonstrates good weldability. However, welding without filler metal is generally not recommended as it may result in excessive ferrite content, compromising the material’s properties.

Heat Treatment
The recommended annealing temperature for Duplex 2205 is between 1868°F and 2012°F (1020°C to 1100°C). While it cannot be hardened through heat treatment, the alloy does work-harden. Special precautions are required to manage its higher coefficient of thermal expansion, which can lead to warping or distortion.

Processing – Hot Forming
For hot forming, the maximum recommended temperature is between 2010°F and 2100°F (1100°C to 1150°C). Uneven cooling, such as cooler edges compared to the bulk, can increase the risk of cracking. Careful handling is essential.

Processing – Cold Forming
Duplex 2205 has good formability but requires careful consideration due to its high strength. The higher springback characteristic of this material must be accounted for during cold forming processes.

Machinability
Duplex 2205 is slightly more challenging to machine compared to 300 series austenitic stainless steels. It requires higher cutting forces, which result in faster tool wear. To optimize machining:

• Use a rigid, powerful machine with strong tool and workpiece mounts.
• Minimize tool extension to reduce vibration.
• Keep the tool nose radius short to maintain a sharp cutting edge while ensuring strength.
• Plan machining sequences so the depth of each cut avoids the work-hardened layer from prior operations.

FABRICATION

Duplex 2205 stainless steel can be fabricated using various techniques, including hot and cold forming, machining, and welding. However, its high strength and hardness require specialized equipment and techniques to avoid damage and ensure optimal results.

• Hot forming: Duplex 2205 can be hot formed at temperatures between 1000°C (1832°F) and 1150°C (2102°F). However, temperatures above 1150°C (2102°F) can cause precipitation of chromium carbides, leading to reduced corrosion resistance. Proper temperature control is crucial to maintain the alloy’s integrity and performance.
• Cold forming: Duplex 2205 can be cold formed using various techniques, including bending, spinning, and drawing. However, its high strength and hardness require higher forces and more powerful equipment compared to austenitic stainless steels. Intermediate annealing may be required to relieve stress and prevent cracking.
• Machining: Duplex 2205 is more difficult to machine than austenitic stainless steels due to its high hardness and strength. Cutting speeds should be reduced by 20-30% to avoid tool wear and damage. Using a powerful, rigid machine with strong tool and workpiece mounts is essential to achieve precise results.
• Welding: Duplex 2205 can be welded using various techniques, including shielded metal arc welding (SMAW), gas metal arc welding (GMAW), and gas tungsten arc welding (GTAW). However, welding requires careful control of heat input and shielding gas to avoid precipitation of chromium carbides and ensure optimal corrosion resistance. Proper post-weld heat treatment may be necessary to restore the alloy’s properties.

By following these guidelines, manufacturers can ensure that Duplex 2205 stainless steel retains its superior properties and performs reliably in demanding applications.

Welding and Joining

Duplex 2205 stainless steel can be effectively welded using various techniques, including shielded metal arc welding (SMAW), gas metal arc welding (GMAW), and gas tungsten arc welding (GTAW). However, welding Duplex 2205 requires meticulous control of welding parameters to prevent precipitation and ensure good corrosion resistance. Proper heat input and shielding gas are essential to maintain the alloy’s properties and achieve optimal weld quality.

2205/31803/S32205 grade austenitic stainless steels pipe

Comparison with Other Grades

When compared to austenitic stainless steels like 316L and 317L, Duplex 2205 stands out due to its higher strength and superior resistance to pitting and crevice corrosion. This makes it particularly suitable for applications in marine environments, oil and gas, and chemical processing. Its high chromium content provides better corrosion resistance in oxidizing environments, while its high chloride resistance makes it ideal for high-chloride environments such as seawater and brine.

Overall, Duplex 2205 stainless steel offers a unique combination of high strength, good corrosion resistance, and weldability, making it a preferred choice for a wide range of demanding applications.

Wide choice of dimensions and free cutting

• Whatever your needs, Daxun Alloys has the perfect stainless steel tube for you. We offer 3m and 6m lengths, with diameters from 3mm to 2000mm (Grade 2205) and ¾” to 20″ (Grade S31803).
• If you require a specific length, we offer a free unlimited cutting service with every purchase. Using state-of-the-art bandsaws and optimized cutting speeds, our precision cutting service can cut the tube to the exact length you require. Just let us know when ordering. It’s another reason why we are a leading stainless steel tube supplier to our domestic and international customers.

Contact your stainless steel tube suppliers

• You can easily order stainless steel pipes online, in any size, in any quantity.
• Alternatively, our friendly sales team will be happy to take your order. Simply call +86 13382898899 or email Daxunhejin@gmail and we will get back to you as soon as possible.