Chemical composition and performance characteristics of 2507 stainless steel seamless pipe

2507 stainless steel seamless pipe is a ferritic-austenitic (duplex) stainless steel with chemical composition (25Cr-7Ni-4Mo-0.27N) 2507 stainless steel, which has excellent resistance to spot corrosion, crevice corrosion and uniform corrosion. The 2507 stainless steel seamless pipe is a ferritic-austenitic (duplex) stainless steel, which combines the most beneficial properties of many ferritic and austenitic steels. Because of the high content of chromium and molybdenum in the steel, it has excellent resistance to spot corrosion, crevice corrosion and uniform corrosion. The duplex microstructure ensures that the steel has high resistance to stress corrosion cracking and high mechanical strength.

Main uses of 2507 stainless steel seamless pipe: 2507 stainless steel is used in oil and natural gas industry; Offshore stone-breaking oil platform (heat exchanger pipe, water treatment and water supply system, fire protection system, water spray system, water stabilization system; petrochemical equipment; desalting (desalination) equipment (and high-pressure pipe and seawater pipe in the equipment); Mechanical and structural parts with high strength and high corrosion resistance are required; Gas (waste) purification equipment.

2507 stainless steel seamless pipe main composition: 25Cr-7Ni-4Mo-0.27N

Comparison of national standards for 2507 stainless steel seamless pipe:

ASTM/ASME: A240 – UNS S32750

EURONORM: 1.4410 – X2 Cr Ni MoN 25.7.4

AFNOR: Z3 CN 25.06 Az

DIN/EN： 1.4410、ASME SA-240

GB: 25Cr-7Ni-4Mo-0.27N

Corrosion resistance

1. General corrosion:

The high content of chromium and molybdenum in SAF 2507 makes it have strong resistance to overall corrosion of organic acids such as formic acid and acetic acid. SAF2507 alloy also has strong corrosion resistance to inorganic acids, especially those containing chlorides.

Compared with 904L, SAF2507 has stronger corrosion resistance to dilute sulfuric acid mixed with chloride ions. 904L is an austenitic alloy specially designed to resist pure sulfuric acid corrosion.

316L grade cannot be used in hydrochloric acid environment, it may be subject to local corrosion or overall corrosion. SAF2507 can be used in dilute hydrochloric acid environment with strong resistance to spot damage and crack corrosion.

2. Intergranular corrosion:

The lower carbon content of nSAF 2507 greatly reduces the risk of carbide precipitation in the intergranular during heat treatment. Therefore, this alloy has strong resistance to intergranular corrosion related to carbide

3. Stress corrosion cracking:

The compound structure of SAF 2507 makes it have strong resistance to stress corrosion cracking. Due to its high alloy content, the corrosion resistance and strength of SAF 2507 are better than 2205

Cracks are almost inevitable in construction and other aspects, which makes stainless steel more susceptible to corrosion in the chloride environment. SAF 2507 has a strong ability to resist crack corrosion. SAF 2507 has an equal corrosion curve of 0.1 mm/year in sulfuric acid containing 2000 ppm chloride ions; Equal corrosion curve in hydrochloric acid 0.1 mm/year

Mechanical properties: SAF 2507 has high compressive strength, impact strength, low coefficient of thermal expansion and high thermal conductivity. These properties are applicable to many structural parts and mechanical components. SAF 2507 has high impact strength, and should not be exposed to temperatures higher than 570 ° F for a long time, which may weaken its toughness. Tensile strength: σ b≥730Mpa; Elongation: δ≥ 20%

Supporting welding materials: ER2594 welding wire, E2594 welding rod

Application fields: pulp and paper industry, seawater desalination, flue gas purification, heat exchanger, chemical tanker pipeline system, seawater system, etc.

Main specifications of 2507 stainless steel:

1.2507 stainless steel plate spot specification: 0.3mm-350mm (thickness)

2.2507 stainless steel bar stock specification: 3.0mm-500mm (diameter)

3.2507 stainless steel wire stock specification: 0.1mm-20mm (wire diameter)

Chemical composition of 2507 stainless steel:

C≤0.03 、Si≤0.80 、Mn≤1.2 、Cr:24-26 、Ni:6-8 、S≤0.02 、P≤0.035 、Mo:3-5 、N:0.24-0.32

After proper solution treatment, the microstructure of 2507 stainless steel seamless pipe is relatively ideal α/γ Biphasic structure with a ratio of about 50/50. When the solid solution temperature is above 1050 ℃, the number of ferrite phases in steel will increase with the increase of temperature, but due to the high nitrogen content, the proportion of ferrite phases below 1300 ℃ will not change significantly. If this steel is not aged at different temperatures (or affected by heat) α+γ There will be γ 2 Formation and δ、χ、 R、 α` The intermetallic phase and Cr2N and other oxides precipitate. Because the carbon content in the steel is low (generally 0.01% – 0.02%), there is generally no carbide in the steel.

Mechanical properties of 2507 stainless steel seamless pipe products:

1、 Mechanical properties of 2507 stainless steel seamless pipe at room temperature:

Steel type: wall thickness ≤ 20mm; δ b/MPa:800-1000 、 δ 0.2/MPa:≥550 、 δ 5/%: ≥ 25, hardness (HV): 290

2、 Mechanical properties of 2507 duplex stainless steel plate at room temperature – 200 ℃:

Steel type temperature/℃ δ b/MPa

Room temperature ≥ 530

Plate 100 ≥ 450

200 ≥400

3、 Mechanical properties of 2507 large diameter seamless pipe

external diameter × Wall thickness δ b/MPa δ 0.2/MPa δ 5/% hardness (HV)

273.0mm × 4.19mm 894 644 40 284

323.9mm × 4.57mm 858 662 45 270

406.4mm × 4.74mm 854 657 41 272