Table 1: Chemical Composition of S32750 (Mass Fraction, wt.%)

Table 2: International Equivalent Grades of S32750

Core Performance & Heat Treatment Rules

1. Mechanical properties (solution annealed): Tensile ≥795 MPa, Yield ≥550 MPa, Elongation ≥15%. Yield strength is over twice that of 304/316L, enabling thinner, lighter structural design under identical load.
2. Corrosion advantage: Critical pitting temperature ~85°C, much higher than 2205 (49°C) and 316L (18°C). Outstanding resistance to seawater, brine, chloride wastewater and medium-concentration acid; effectively blocks chloride stress corrosion cracking (SCC).
3. Standard solution annealing: Heat to 1050–1120°C, hold thoroughly then rapid water quenching. Long stay at 800–980°C precipitates brittle σ-phase, drastically dropping toughness and corrosion resistance.
4. Limitation: Continuous service temperature not exceeding 250–300°C; poor ductility for heavy cold forming; welding requires precise heat input control to protect dual-phase balance.

Main Application Fields

1. Offshore & desalination industry: Seawater intake pipelines, desalination heat exchanger tubes, offshore platform process piping, seawater pumps & high-pressure valves.
2. Oil & gas exploitation: Downhole tubing, wellhead fittings, separator equipment, pipelines for brine-containing crude oil, certified under NACE anti-sulfide standard.
3. Chemical & environmental protection: Flue gas desulfurization (FGD) absorption towers, chloride medium reactors, chemical sewage pipelines, mixed acid storage equipment.
4. Marine & shipbuilding: Ship seawater cooling systems, ballast pipelines, corrosion-resistant hull auxiliary structural parts.
5. Special pressure equipment: High-pressure corrosion-resistant vessels, heat exchangers for brine processing and pharmaceutical corrosive medium production lines.