2507

2507 (UNS S32750) is a high-performance super austenitic-ferritic duplex stainless steel, mainly composed of chromium, nickel, molybdenum, and nitrogen. It features a balanced dual-phase structure (~50% austenite + ~50% ferrite), which integrates the excellent corrosion resistance of super austenitic stainless steel and the ultra-high strength of ferritic stainless steel. It exhibits extreme resistance to chloride stress corrosion cracking (SCC) and pitting/crevice corrosion (PRE ≥ 40), outstanding mechanical properties in the temperature range of -50 °C to 300 °C, and ultra-high tensile strength (≥800 MPa). These characteristics make it ideal for ultra-harsh environments with high-concentration corrosive media (especially chloride-containing) and extreme structural load requirements.​.

Behaviour that matters in service

• Extreme Chloride Corrosion Resistance — Far superior to 2205/316L in resistance to chloride stress corrosion cracking, pitting, and crevice corrosion (suitable for high-concentration brine, high-temperature seawater, and strong acidic chloride media).​.
• Ultra-High Mechanical Strength — Tensile strength (≥800 MPa) and yield strength (≥550 MPa) are 2 – 3 times higher than 304/316 stainless steel; further reduces component thickness and weight, cutting long-term costs.​.
• Balanced Dual-Phase Structure — ~50% austenite + ~50% ferrite ensures excellent low-temperature toughness (no brittle fracture at -50 °C) and fatigue resistance, avoiding the brittleness of single-phase ferritic steels.​.
• Controllable Weldability — Compatible with standard welding methods (TIG, MIG); strict heat input control (0.5 – 1.5 kJ/mm) maintains post-weld dual-phase balance and corrosion resistance; self-fusion welding requires post-weld annealing.​.
• Medium-Temperature Stability — Maintains stable performance at temperatures up to 300 °C; avoids phase transformation or toughness degradation under long-term medium-temperature service.​.

Typical applications

• Deep-Sea Oil & Gas Industry — Used in subsea wellhead equipment, high-pressure pipelines for offshore platforms, and acidizing fracturing tools; withstands high-pressure, high-salinity, and H₂S-containing media.​.
• High-Concentration Seawater Desalination — Applied to reverse osmosis (RO) high-pressure membrane housings and brine discharge pipelines; resists extreme chloride erosion.​.
• Strong Corrosion Chemical Industry — Used in high-concentration hydrochloric acid reactors, sulfuric acid recovery systems, and chemical liquid cargo ship pipelines; avoids pitting/crevice corrosion in harsh acidic environments.​.
• Environmental Engineering — Employed in flue gas desulfurization (FGD) systems and high-concentration sewage treatment equipment; resists corrosion from acidic flue gas and toxic sludge.​.
• Extreme Marine Engineering — Used in deep-sea ship hull components, underwater propeller shafts, and offshore wind power platform structures; combines ultra-high strength and long-term seawater corrosion resistance.