S32750 Super Duplex Pipe Tube Tubing

ASTM A789 ASME SA 789 SAF 2507 UNS S32750 (EN 10216 – 5 1.4410) Stainless Steel is super duplex stainless steel with 25% chromium, 4% molybdenum, and 7% nickel designed for demanding applications which require exceptional strength and corrosion resistance, such as chemical process, petrochemical, and seawater equipment.

ASTM A789 S32750 (Super Duplex Stainless Steel Tubes) Key Performance Characteristics and Technical Features

1. Key Performance Characteristics of ASTM A32750

• Exceptional Corrosion Resistance:
  • Outstanding resistance to pitting, crevice corrosion, and chloride stress corrosion cracking (SCC).
  • Higher alloy content (Cr, Mo, N) compared to standard duplex grades (e.g., S32205), with PREN ≥ 40 (Cr + 3.3Mo + 16N).
  • Suitable for extreme environments (seawater, acidic/chloride-rich media, oil/gas sour service).
• Ultra-High Mechanical Strength:
  • Superior tensile strength (≥800 MPa) and yield strength (≥550 MPa), exceeding standard duplex and austenitic steels.
  • Maintains good ductility (elongation ≥15%) despite high strength.
• Balanced Ferrite-Austenite Microstructure:
  • Optimized phase ratio (~50:50 ferrite-austenite) ensures toughness, fatigue resistance, and corrosion stability.
  • Enhanced resistance to intermetallic phase formation with proper heat treatment.
• Weldability and Fabrication:
  • Weldable using TIG, MIG, or SAW methods, but requires strict control of heat input and shielding gas (e.g., nitrogen addition).
  • Post-weld annealing may be needed to restore corrosion resistance in critical applications.
• Temperature Performance:
  • Retains mechanical properties from cryogenic temperatures up to 300°C (short-term exposure to 350°C possible).

2. Technical Elements of ASTM A789 S32750

• Chemical Composition (Typical wt%):
  • Cr: 24.0–26.0%, Ni: 6.0–8.0%, Mo: 3.0–4.0%, N: 0.24–0.32%, C: ≤0.030%, Mn: ≤1.2%, Si: ≤0.8%.
• Heat Treatment:
  • Solution annealing at 1040–1120°C followed by rapid quenching (water or air) to avoid harmful phase precipitation (e.g., sigma phase).
• Manufacturing Standards:
  • Covers seamless and welded stainless steel tubes for corrosive and high-pressure applications.
  • Complies with ASTM A789 specifications and aligns with NACE MR0175/ISO 15156 for sour service environments.
• Testing and Certification:
  • Mandatory hydrostatic, nondestructive testing (NDT), and hardness checks.
  • Corrosion testing per ASTM G48 (critical pitting temperature > 50°C).
  • Impact testing for low-temperature applications.
• Key Applications:
  • Offshore oil/gas systems, subsea pipelines, chemical reactors, desalination plants, and marine heat exchangers.

Summary

ASTM A789 S32750 super duplex stainless steel pipe combines extreme corrosion resistance, ultra-high strength, and robust performance in aggressive environments. Its advanced alloy design, strict heat treatment protocols, and compliance with ASTM standards make it ideal for demanding industries requiring reliability under high stress, pressure, and corrosive conditions.

SUPER DUPLEX 2507 ASTM A789 S32750 STAINLESS STEEL TUBES CHEMICAL COMPOSITION:

After proper solution treatment of 2507 stainless steel, the microstructure of the steel is more ideal than the dual phase structure of alpha / gamma ratio of 50/50. When the solution temperature is above 1050 DEG C, the ferrite phase number increases with the increase of temperature, but because of the high nitrogen content, there is no significant change in the phase ratio below 1300. This steel without aging at different temperature (or heat effect), in the alpha + gamma matrix will be formed and delta gamma 2, x, R, alpha ` intermetallic phases and Cr2N oxide precipitates, because the carbon content of the steel is low (usually 0.01%-0.02%), so in general no carbide steel.