What Is Super Duplex 2507 Stainless Steel?

What is 2507 duplex stainless steel? 2507 super duplex stainless steel / UNS S32750 is a ferritic-austenitic (duplex) stainless steel with excellent resistance to pitting, crevice corrosion and uniform corrosion.

Internationally known as:

SAF 2507, UNS S32750, NAS 74N, F53, W.-Nr. 1.4410

Executive standard:

ASTM A240/ASME SA-240, ASTM A276, ASTM A182/ASME SA-182, ASTM A312/ASMES A312

Chemical composition: 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

Physical properties:

Density of 2507 duplex steel: 8.03g/cm3, melting point: 1300-1390 ℃

Heat treatment:

Keep the temperature between 1000-1052℃ for 1-2 hours, fast air cooling or water cooling.

Mechanical behavior:

Tensile strength: σb≥795Mpa, yield strength σb≥550Mpa: elongation: δ≥15%, hardness ≤310 (HB)

Corrosion resistance

1. Corrosion resistance

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

Compared with 904L, SAF2507 has stronger corrosion resistance to diluted sulfuric acid mixed with chloride ions.904L is an austenitic alloy, which is specially used to resist the corrosion of pure sulfuric acid.

316L grade cannot be used in hydrochloric acid environment, it may suffer local corrosion or overall corrosion. SAF2507 can be used in diluted hydrochloric acid environment and has strong resistance to spot damage and crevice corrosion.

2. Intergranular corrosion

The lower carbon content of SAF 2507 greatly reduces the risk of carbide precipitation in the intergranular during heat treatment. Therefore, this alloy has a strong ability to resist intergranular corrosion related to carbides.

3. Stress corrosion cracking

The duplex structure of SAF 2507 gives it strong resistance to stress corrosion cracking. Due to its higher 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 a chloride environment. SAF 2507 has a strong resistance to crack corrosion. SAF 2507's isocorrosion curve in sulfuric acid containing 2000ppm chloride ion 0.1 mm/year; isocorrosion curve in hydrochloric acid 0.1 mm/year.

Mechanical properties: SAF 2507 has high compressive strength, impact strength, low thermal expansion coefficient and high thermal conductivity. These characteristics are suitable for many structural parts and mechanical parts. SAF 2507 has high impact strength and is not suitable for long-term placement In a temperature environment higher than 570°F, this may weaken its toughness. Tensile strength: σb≥730Mpa; Elongation: δ≥20%

Matching welding materials: ER2594 welding wire, E2594 welding rod

Application areas: pulp and paper industry, seawater desalination, flue gas purification, heat exchangers, chemical tanker piping systems, seawater systems, etc.