S25073 Super Duplex Stainless Steel Product Introduction

‌1. Material Overview‌
S25073 (UNS S25073 / F55 / EN 1.4507) is a hyper-duplex stainless steel engineered for extreme environments. It features a balanced ferritic-austenitic microstructure with enhanced alloying, positioning it between standard duplex (e.g., S31803) and nickel alloys in performance hierarchy.

‌2. Chemical Composition‌
Controlled chemistry includes 24-26% chromium, 6-8% nickel, 3.0-4.0% molybdenum, 0.20-0.30% nitrogen, and 0.5-1.0% copper. Low carbon content (<0.030%) and tightly managed impurities optimize corrosion resistance.

‌3. Key Performance Attributes‌

• ‌Corrosion Resistance‌:
  • PREN ≥45 (superior to S32760)
  • Exceptional resistance to chloride pitting/crevice corrosion, acid attack, and stress corrosion cracking (SCC)
• ‌Mechanical Strength‌:
  • Minimum yield strength: 550 MPa (≈2× 316L stainless steel)
  • Impact toughness maintained down to -40°C
• ‌Thermal Stability‌:
  • Continuous service: -50°C to 300°C
  • Avoid 550-900°C range to prevent σ-phase embrittlement

‌4. Industry Applications‌

• ‌Oil & Gas‌: Subsea manifolds, X-mas trees, sour service pipelines (NACE MR0175 compliant)
• ‌Chemical Processing‌: Agitators in HCl environments, sulfuric acid coolers
• ‌Marine Technology‌: Offshore risers, seawater injection systems
• ‌Energy‌: Flue gas scrubber components, geothermal brine piping

‌5. Fabrication Advantages‌

• ‌Weldability‌: Compatible with TIG/SAW using ER2594 filler metal. Requires controlled heat input (0.5-1.5 kJ/mm) and interpass temp <100°C.
• ‌Machinability‌: 35% lower cutting speeds than 304 stainless recommended; use positive-geometry carbide tools.
• ‌Formability‌: Cold-working possible but annealed state (1040-1100°C WQ) preferred for severe forming.

‌6. Competitive Differentiation‌

• Replaces high-nickel alloys (e.g., Alloy 625) in aggressive media, reducing material costs by 30-40%
• Outperforms standard super duplex grades in sulfide stress cracking (SSC) resistance
• Certified to ASTM A182 F53 / ASME SA-182 for pressure equipment