S31803 Duplex Stainless Steel Product Overview

1. Material SpecificationsS31803 (UNS S31803), also known as 2205 duplex stainless steel, is a chromium-nickel-molybdenum-nitrogen alloy with a balanced ferritic-austenitic microstructure. This material meets ASTM A790 and ASTM A928 standards for seamless and welded pipe applications.

2. Chemical CompositionThe alloy contains 21-23% chromium, 4.5-6.5% nickel, 2.5-3.5% molybdenum, and 0.14-0.20% nitrogen, with controlled carbon content below 0.030%. The balanced composition provides excellent corrosion resistance and mechanical properties.

3. Key CharacteristicsS31803 offers superior resistance to stress corrosion cracking compared to standard austenitic grades. Its pitting resistance equivalent number (PREN) exceeds 35, ensuring performance in chloride-containing environments. The material demonstrates approximately double the yield strength of 304/316 stainless steels while maintaining good toughness.

4. Physical PropertiesTypical density is 7.8 g/cm³ with thermal expansion coefficients between those of carbon steel and austenitic stainless steels. The alloy maintains structural integrity in temperatures ranging from -50°C to 300°C.

5. ApplicationsPrimary uses include chemical processing equipment, oil and gas pipelines, marine components, and pollution control systems. The material is particularly suitable for applications requiring both high strength and corrosion resistance such as pressure vessels, heat exchangers, and seawater handling systems.

6. Fabrication NotesStandard welding methods including TIG, MIG, and SAW are applicable using matching filler metals. The alloy can be machined using carbide tools with proper cooling. Post-weld heat treatment is generally not required.