Duplex Steel Products
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Table of Contents
- Introduction to Duplex Steel Products
- Duplex Steel Grades Overview
- Standard Specifications
- Chemical Composition Comparison (%)
- Mechanical Properties (Typical)
- Key Applications by Industry
- Advantages Over Austenitic Stainless Steel
- Why Choose Stellar Alloys for Duplex Steel Products?
- Quality Assurance & Testing
- Stock Availability
- Frequently Asked Questions
Stellar Alloys is a leading supplier of duplex steel products and a worldwide producer of high-strength stainless steel products that cut in the gap amidst ferritic and austenitic alloy. Our products are complete in terms of duplex steel products, such as seamless and welded pipes, heat exchanger tubes, plates, sheets, flanges, fittings, and round bars of key grades like Duplex 2205 (UNS S31803/S32205), Duplex 2304, and LDX 2101. Our materials are essential to the oil and gas industry, chemical processing industry and marine industry with a special dual-phase microstructure that offers twice the yield strength of conventional stainless steels and high resistance to chloride stress corrosion cracking (SCC). Buyers of our products are assured of high quality and standards of ASTM A790, A789 and A240 with full mill test certification, advanced quality testing and global logistics to deliver our products within your project deadlines.
Available Grades of Duplex Steel
Duplex Steel Pipes & Tubes
Seamless and welded pipes in grades 2205 and 2304 for high-pressure environments.
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Duplex Steel Plates
High-strength plates and sheets with superior corrosion resistance.
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Duplex Steel Flanges & Fittings
Complete range of forged fittings, flanges, and pipe fittings.
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Introduction to Duplex Steel Products
The name Duplex Stainless Steel is derived because it has a two-phase microstructure which is a combination of about 50/50 austenite and ferrite grains. This special construction is the combination of the finest qualities of the two types of steel: the strength and stress corrosion cracking hardness of ferritic stainless steels and toughness and fabrication ease of austenitic stainless steels.
The greatest benefit of duplex steel is that it is strong- it normally has twice the yield strength of a normal austenitic steel such as 304 and 316. This enables the design engineers to employ a low wall thickness in piping and vessels, which decreases total weight and material expenditure. Also, the ferritic phase offers better resistance to chloride stress corrosion cracking (SCC), commonly used failure modes in warm, chloride-laden conditions where austenitic steels frequently fail.
Stellar Alloys is your trusted supplier and producer of duplex steels with a complete range of grades, starting with the “Lean Duplex” (S32304) and continuing to the “Standard Duplex” (2205). Our materials are also designed to work in rough offshore, chemical tankers and desalination plants.
Duplex Steel Pipes & Tubes
We supply high-performance Duplex Steel pipes and tubes designed for high-pressure, corrosive environments in process industries.
| Specification | Details |
|
Size Range |
Seamless: 1/2″ NB to 24″ NB Tubes: 6mm to 610mm OD |
|
Schedules |
SCH 5S, 10S, 40S, 80S, 160, XXS |
|
Standards |
ASTM A790, A789, ASME SA790, SA789 |
|
Types |
Seamless, Welded, ERW, EFW |
|
Key Grades |
Duplex 2205, Duplex 2304 |
Duplex Steel Plates & Sheets
Our inventory includes Duplex Steel plates and sheets ideal for storage tanks, pressure vessels, and structural components requiring high strength.
| Specification | Details |
|
Thickness |
0.5mm to 100mm |
|
Width |
1000mm, 1219mm, 1500mm, 2000mm |
|
Length |
2000mm, 2440mm, 3000mm, 6000mm |
|
Finish |
Hot Rolled (No.1), Cold Rolled (2B) |
|
Standards |
ASTM A240, ASME SA240 |
Duplex Steel Flanges & Fittings
Durable flanges and fittings manufactured to ensure secure, leak-proof connections in high-pressure systems.
| Specification | Details |
|
Types |
Weld Neck, Slip-On, Blind, Socket Weld, Threaded |
|
Standards |
ASME B16.5, B16.47, B16.9, ASTM A815 |
|
Pressure Class |
150#, 300#, 600#, 900#, 1500#, 2500# |
|
Fittings |
Elbows, Tees, Reducers, Caps, Stub Ends |
Duplex Steel Grades Overview
Grade | UNS No. | Key Features | Corrosion Resistance (PREN) | Primary Applications |
S31803 / S32205 | Standard duplex grade. High strength, good toughness. | PREN ≥ 35. Excellent pitting/SCC resistance. | Oil & gas piping, chemical tanks, pulp & paper. | |
Duplex 2304 | S32304 | “Lean” duplex. Low Molybdenum. Cost-effective. | PREN ≥ 24. Better than 316L in many cases. | Infrastructure, bridges, food storage. |
LDX 2101 | S32101 | Lean duplex with high Manganese, low Nickel. | PREN ≥ 26. High strength alternative to 304. | Storage tanks, water treatment, construction. |
Standard Specifications
Product Form | ASTM Standards |
Pipes (Seamless & Welded) | ASTM A790, ASME SA790, ASTM A928 |
Tubing | ASTM A789, ASME SA789 |
Plates & Sheets | ASTM A240, ASME SA240 |
Flanges | ASME B16.5, B16.47, ASTM A182 (F51, F60) |
Fittings | ASTM A815, ASME B16.9 |
Bars & Rods | ASTM A276, A479 |
Chemical Composition Comparison (%)
Grade | Cr | Ni | Mo | N | C (max) | Mn |
2205 (S32205) | 22.0-23.0 | 4.5-6.5 | 3.0-3.5 | 0.14-0.20 | 0.030 | 2.00 |
2304 (S32304) | 21.5-24.5 | 3.0-5.5 | 0.05-0.60 | 0.05-0.20 | 0.030 | 2.50 |
Mechanical Properties (Typical)
Grade | Tensile Strength (min) | Yield Strength (0.2% min) | Elongation (min) | Hardness (max) |
Duplex 2205 | 655 MPa (95 ksi) | 450 MPa (65 ksi) | 25% | 293 HB / 31 HRC |
Duplex 2304 | 600 MPa (87 ksi) | 400 MPa (58 ksi) | 25% | 290 HB / 32 HRC |
Key Applications by Industry
- Oil & Gas : Subsea pipelines, flowlines, manifolds, and wellheads. Duplex steel is essential for resisting CO2 and H2S corrosion in offshore environments.
- Chemical Processing : Pressure vessels, reactors, storage tanks, and heat exchangers handling chlorides, organic acids, and other corrosive chemicals.
- Marine & Offshore : Desalination plants (SWRO), seawater systems, fire-fighting systems, and propellers where high strength and pitting resistance are required.
- Pulp & Paper : Digesters, bleaching equipment, and brown stock washers. Duplex withstands the corrosive liquors and high temperatures of the pulping process.
- Power Generation : Flue Gas Desulfurization (FGD) systems, absorbers, and slurry pumps. Duplex resists the acidic, abrasive slurries found in scrubbers.
- Food & Beverage : Storage tanks and processing equipment for foods with high chloride content (like soy sauce or dairy), where standard 304/316 may suffer pitting.
Advantages Over Austenitic Stainless Steel
- High Strength: Yield strength is roughly double that of 304/316, allowing for thinner walls and lighter structures.
- SCC Resistance: Superior resistance to chloride stress corrosion cracking compared to austenitic grades.
- Pitting Resistance: Better pitting and crevice corrosion resistance than 316L (especially 2205).
- Cost Efficiency: Lower Nickel content (approx 5% vs 10% in 316) makes duplex prices more stable.
- Thermal Expansion: Lower coefficient of thermal expansion than austenitic steel, closer to carbon steel.
Why Choose Stellar Alloys for Duplex Steel Products?
Stellar Alloys delivers certified high-strength duplex solutions.
- Comprehensive Inventory: Extensive stock of Duplex 2205 pipes, plates, and fittings.
- Certified Quality: Materials supplied with Mill Test Certificates (EN 10204 3.1) per ASTM/ASME/NACE standards.
- Global Logistics: Expertise in exporting to over 40 countries with seaworthy packaging.
- Technical Support: Metallurgical guidance on welding and fabrication of duplex alloys.
- Custom Fabrication: Cutting, beveling, and threading services available in-house.
Quality Assurance & Testing
We perform rigorous testing to ensure material integrity:
- Positive Material Identification (PMI)
- Ferrite Content Testing
- Mechanical Testing (Tensile, Yield, Hardness)
- Intergranular Corrosion Testing (ASTM A262)
- Critical Pitting Temperature (CPT) Testing
- Hydrostatic Testing for pipes
- Ultrasonic Testing (UT)
Stock Availability
We maintain ready stock for quick delivery:
- Duplex 2205 Seamless Pipes, Plates, Bars
- Duplex 2304 Plates, Welded Pipes
- Duplex Fittings Elbows, Flanges (F51)
- Heat Exchanger Tubes ASTM A789 Seamless
Frequently Asked Questions
Duplex steel is a family of stainless steels that have a mixed microstructure of approximately 50% ferrite and 50% austenite. This combination provides high strength and excellent corrosion resistance.
Duplex 2205 is the standard grade with about 3% molybdenum, offering high corrosion resistance suitable for severe environments. Duplex 2304 is a “lean” grade with almost no molybdenum; it is cheaper and stronger than 316L but has slightly lower pitting resistance than 2205.
In terms of strength and chloride stress corrosion cracking resistance, yes. Duplex is twice as strong as 316. However, 316 may be better for extremely low cryogenic temperatures or certain highly oxidizing acids.
Because of its dual-phase microstructure consisting of two grain types: ferrite and austenite.
Yes, but it requires specific procedures to maintain the phase balance and corrosion resistance. Controls on heat input and interpass temperature are critical, and filler metals usually contain higher nickel (e.g., 2209 for 2205).
Yes, duplex stainless steel is magnetic due to its ferritic phase. This distinguishes it from austenitic grades like 304 and 316, which are non-magnetic.
Super Duplex (like 2507) contains higher Chromium (25%), Molybdenum (4%), and Nitrogen. This gives it significantly higher pitting resistance (PREN > 40) and strength compared to standard Duplex 2205.
Primarily for cost savings through weight reduction (due to higher strength) and for better reliability in environments where stress corrosion cracking is a risk.
UNS S32205 is a restricted chemistry version of S31803 with higher minimum Chromium, Molybdenum, and Nitrogen. It ensures better corrosion properties. The most modern 2205 is dual-certified as S31803/S32205.
Like all stainless steels, it can corrode if exposed to environments beyond its capability (e.g., extremely concentrated chlorides or acids), but it is generally much more resistant to rust than carbon steel or lower grade stainless steels.