Duplex Stainless Steel

2205 Stainless Steel

Duplex stainless steel grade 2205 (also known as UNS S31803/S32205, ASTM A240 Type 2205, Inox 2205, AISI 318LN, SUS 329J3L, or EN 1.4462) is a two-phase (ferritic-austenitic) alloy containing about 22–23% chromium, 2.5–3.5% molybdenum, 4.5–6.5% nickel, and roughly 0.15% nitrogen. Its balanced microstructure provides a unique combination of high strength and excellent corrosion resistance. For example, grade 2205 typically has about twice the yield strength of 316L stainless steel, allowing designers to use much thinner, lighter sections without sacrificing performance.

The alloy is normally supplied in the solution-annealed condition (per ASTM A240/A240M) to retain an ideal duplex structure. Grade 2205 remains tough from cryogenic temperatures (around –50°C) up to about +300°C; beyond this range, brittle sigma phase can form in welds. These properties make duplex 2205 an excellent choice for demanding applications such as chemical processing, offshore oil & gas, and marine environments where both high strength and chloride corrosion resistance are required.

Key Advantages of Duplex 2205

Exceptional Strength-to-Weight Ratio: Grade 2205 offers yield strength roughly double that of common austenitic stainless steels. This allows structures (vessels, tanks, pipes, etc.) to be built 30–50% thinner, significantly reducing weight and material costs while maintaining the same pressure ratings or load capacity.

Outstanding Corrosion Resistance: The high chromium, molybdenum, and nitrogen content gives 2205 stainless steel much better general corrosion resistance than 316L/317L. It resists pitting and crevice corrosion in chloride-bearing environments far more effectively than 300-series grades. In aggressive media or seawater, duplex 2205 often outperforms conventional austenitics; super duplex alloys can even substitute for more expensive nickel alloys in the harshest conditions.

Superior Stress Corrosion Cracking Resistance:The duplex microstructure delivers exceptional resistance to chloride stress corrosion cracking (SCC). Even lean duplex grades far outperform 304/316 stainless in SCC tests. This makes 2205 ideal for wet, saline, or brackish environments (marine applications, desalination, seawater cooling, etc.) where austenitic steels would crack under stress.

High Toughness and Fatigue Strength: Duplex 2205 maintains excellent toughness (even at sub-zero temperatures) and resists crack growth under cyclic loading much better than equivalent austenitic alloys. It absorbs more energy under impact or vibration, making it more robust under dynamic or emergency loads. Its higher hardness compared to annealed 304/316 also provides improved wear resistance in abrasive conditions.

Low Thermal Expansion and Carbon-Steel Compatibility:Grade 2205 has a relatively low coefficient of thermal expansion (near that of carbon steel). This is advantageous when welding or clad laminating to carbon steel, since the similar expansion rates reduce stress and distortion. It also maintains dimensional stability across temperature changes better than 300-series alloys.

Chemical Processing

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Automotive Components

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Domestic Goods

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Chemical Processing

Culinary Sector

Farming Sector

Maritime Construction

Heat Exchange

APliable Tubing

Automotive Components

Medical Instruments

Domestic Goods

Construction Building Materials

Chemical Processing

Culinary Sector

Farming Sector

Maritime Construction

Heat Exchange

APliable Tubing

Automotive Components

Medical Instruments

Domestic Goods

Construction Building Materials

Chemical Processing

Culinary Sector

Farming Sector

Maritime Construction

Heat Exchange

APliable Tubing

Automotive Components

Medical Instruments

Domestic Goods

Construction Building Materials

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Chemical and Process Industries: Ideal for pressure vessels, high-pressure storage tanks, piping, and heat exchangers in chemical plants, acid production, and petrochemical refineries. It handles corrosive acids, alkalis, and solvents where 300-series stainless might fail.

Oil, Gas and Offshore: Used in pipelines, risers, separators, and platform components. Its resistance to chloride stress corrosion cracking makes it valuable for seawater injection pumps, saltwater pipelines, and marine environments in offshore exploration and production.

Water Treatment and Desalination: Employed in seawater cooling systems, desalination plants, and wastewater treatment. Duplex 2205’s pitting resistance ensures long service life in contact with brines or treated water.

Pulp & Paper Industry: Used in digesters, bleaching towers, and chemical storage tanks. It withstands the high temperatures and aggressive chemicals (like chlorine dioxide and caustic liquor) encountered in pulping and bleaching processes.

Food, Beverage and Pharmaceutical Processing: Suitable for tanks, pipes, and equipment in food processing, brewing, dairy, and pharmaceutical plants. It offers strength and corrosion resistance under rigorous sanitary cleaning and hygiene standards.

Industrial Machinery and Marine Components: Applied in pump and valve parts, impellers, shafts, and structural components that require high strength and corrosion resistance. Also used in shipbuilding, offshore structures, and transport containers exposed to harsh conditions.

Other Engineering Uses: Wherever a combination of high strength, toughness, and corrosion resistance is needed. Examples include fasteners, flanges, heat exchanger tubing, and structural parts in power generation, mining, and general manufacturing.

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