2205 Duplex Stainless Steel Coil Tube — Yield Strength (Rp0.2) Specification
Product Overview
The 2205 Duplex Stainless Steel Coil Tube is a high-performance austenite-ferrite (AF) duplex alloy offered by Wenzhou Jixing Metal Materials Co., Ltd. as a coiled (coil) tube configuration. This product is engineered to deliver exceptional mechanical properties, particularly in yield strength, while maintaining outstanding resistance to pitting, crevice corrosion, and stress corrosion cracking (SCC). The coil tube form factor provides manufacturing flexibility, enabling downstream users to cold-form, roll, or cut the material to custom geometries without compromising metallurgical integrity.
The defining characteristic of this product is its superior yield strength at both ambient and elevated temperatures — a direct consequence of the balanced austenite-ferrite microstructure inherent to the 2205 duplex system. Compared to conventional austenitic grades such as 304 (UNS S30408), the 2205 coil tube delivers approximately twice the yield strength, making it the material of choice for applications demanding high structural integrity at reduced wall thickness.
Material & Properties
The 2205 Duplex Stainless Steel coil tube is classified under the following standards:
- ASTM A790 / A790M — Standard Specification for Austenitic and Duplex Stainless Steel Welded Seamless and Welded Pipe
- ISO 3506 — Stainless and Heat-Resistant Steels and Alloys — Chemical Composition of Semi-Finished Products for Forging
- EN 10217-7 — Stainless Steel Tubes for Technical Use — Part 7: Seamless Tubes for Heat-Resistant and Corrosion-Resistant Grades
- NACE MR0175 / ISO 15156 — Materials for Use in H₂S-Containing Environments in Oil and Gas Production
Chemical Composition (Typical, wt%)
| Element | C | Mn | P | S | Si | Cr | Ni | Mo | N | Fe |
|---|---|---|---|---|---|---|---|---|---|---|
| Specification | ≤0.030 | ≤2.00 | ≤0.030 | ≤0.020 | ≤1.00 | 22.0–23.0 | 4.0–7.0 | 3.0–3.5 | 0.14–0.20 | Bal. |
Mechanical Properties
| Property | Test Condition | 2205 Duplex | 304 Austenitic (Comparison) |
|---|---|---|---|
| Yield Strength (Rp0.2) | Room Temperature (RT, 20°C) | ≥ 450 MPa | ≥ 205 MPa |
| Tensile Strength (Rm) | Room Temperature | 550–800 MPa | 515–730 MPa |
| Elongation (A) | Room Temperature | ≥ 25% | ≥ 40% |
| Yield Strength at 400°C | Elevated Temperature | ≥ 370 MPa | ≥ 125 MPa |
| Yield Strength at 600°C | Elevated Temperature | ≥ 280 MPa | ≥ 65 MPa |
| Impact Energy (Charpy V) | −40°C | ≥ 47 J | ≥ 47 J |
Corrosion Resistance
- Pitting Resistance (PREN): ≥ 35 (vs. PREN ≈ 19 for 304)
- Equivalent Pitting Resistance Number: PREN = %Cr + 3.3 × %Mo + 16 × %N
- Resistance to chloride-induced Stress Corrosion Cracking (SCC) is superior to 304/316 austenitic grades
- Approved for H₂S service per NACE MR0175/ISO 15156, Condition 1 and Condition 2
Specifications
| Parameter | Specification / Range |
|---|---|
| Material Grade | UNS S31803 / 1.4462 / 022Cr23Ni5Mo3N (2205 Duplex) |
| Form | Coil Tube (Continuous Coiled Seamless or Welded) |
| Outer Diameter (OD) | 6.00 mm – 108.00 mm (configurable) |
| Wall Thickness | 0.50 mm – 6.00 mm (configurable) |
| Coil Length | Up to 2,000 m per coil (standard); custom lengths available |
| Surface Finish | Pickled & Passivated (2B), Bright Annealed (BA), or Custom |
| Heat Treatment | Solution Annealed at 1050–1100°C, followed by rapid water quench |
| Microstructure | Balanced Austenite (50–60%) / Ferrite (40–50%) with controlled δ-ferrite distribution |
| Yield Strength (Rp0.2, RT) | ≥ 450 MPa |
| Delivery Condition | As-Annealed (Solution Annealed) |
| Standards Compliance | ASTM A790, EN 10217-7, ISO 3506, NACE MR0175 |
| Non-Destructive Testing | 100% Eddy Current (EC), Hydrostatic Test, Visual Inspection |
Manufacturing Process
The production of 2205 Duplex Stainless Steel Coil Tubes follows a rigorous metallurgical and mechanical processing sequence:
- Slab Preparation: Primary casting via Continuous Casting (CC) or Vacuum Arc Remelting (VAR) to achieve the required 22Cr-5Ni-3Mo-N composition with controlled inclusion morphology.
- Hot Rolling: Slabs are reheated to 1,100–1,200°C and hot-rolled to semi-finished coil stock with controlled reduction ratios to maintain a uniform austenite-ferrite balance.
- Solution Annealing: The hot-rolled coil is solution-annealed at 1,050–1,100°C followed by rapid water quenching to dissolve σ-phase precipitates and restore the optimal ~50:50 austenite-ferrite phase balance.
- Tube Piercing / Forming: The annealed coil is processed through a seamless piercing mill or a cold-drawn/cold-rolled tube forming line to achieve the target OD and wall thickness.
- Intermediate Annealing: Where cold work exceeds 30% reduction, intermediate annealing is performed to prevent work hardening and maintain ductility.
- Final Annealing & Pickle-Passivate: Final solution anneal followed by acid pickling (HNO₃/HF) and passivation to remove scale and establish a stable chromium oxide passive film.
- Coiling & Inspection: The finished tube is coiled to the specified coil length, subjected to 100% non-destructive testing (eddy current, hydrostatic pressure test), and packaged for delivery.
Applications
The exceptional yield strength and corrosion resistance of the 2205 Duplex Coil Tube make it suitable for a wide range of demanding industrial applications:
- Oil & Gas Industry: Subsea pipelines, wellhead equipment, heat exchanger tubes, offshore platforms — where high strength and H₂S resistance are critical (NACE MR0175 compliant).
- Chemical Processing: Reactor vessels, heat exchangers, distillation columns, and piping systems handling chlorides, acids, and aggressive chemical media.
- Marine & Offshore: Seawater piping, ballast tanks, heat exchangers, and structural components exposed to chloride-rich environments.
- Pulp & Paper Industry: Bleaching systems, digesters, and washers where chlorinated alkaline solutions are present.
- Power Generation: Boiler tubes, superheater elements, and condensers operating at elevated temperatures and pressures.
- Food & Pharmaceutical: Sanitary-grade coil tubing for hygienic processing systems requiring high mechanical strength and corrosion resistance.
- Structural Engineering: Architectural cladding, bridge components, and wind turbine structural elements where weight reduction and durability are paramount.
Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management and product certification framework:
- ISO 9001:2015 — Quality Management System certification for manufacturing operations
- ISO 14001:2015 — Environmental Management System certification
- ISO 45001:2018 — Occupational Health & Safety Management System
- API Q1 (ASME Q1) — Quality Management Systems for Petroleum and Natural Gas Industry
- API 5L / API 5CT — Product certification for line pipe and casing/tubing applications
- EN 10204 Type 3.1 — Full product documentation with third-party inspection and test certificates
- CE Marking — Conformity with European Pressure Equipment Directive (PED 2014/68/EU)
- NACE MR0175 / ISO 15156 — Material certification for sour service environments
Unique Selling Points
The 2205 Duplex Stainless Steel Coil Tube from Wenzhou Jixing Metal Materials Co., Ltd. offers a compelling combination of properties that distinguish it from conventional austenitic alternatives:
- Double the Yield Strength: With Rp0.2 ≥ 450 MPa at room temperature — approximately twice that of 304 stainless steel (≥ 205 MPa) — this material enables significant wall thickness reduction, resulting in weight savings of 30–50% while maintaining or exceeding structural performance.
- Elevated Temperature Performance: Retains high yield strength at operating temperatures up to 600°C, making it suitable for high-temperature process applications where 304/316 grades would suffer unacceptable strength loss.
- Superior Corrosion Resistance: A PREN ≥ 35 provides exceptional resistance to pitting and crevice corrosion in chloride-containing environments, far exceeding the PREN ≈ 19 of 304.
- Stress Corrosion Cracking Immunity: The ferritic phase in the duplex microstructure provides inherent resistance to chloride-induced SCC, a known failure mode for austenitic 304/316 grades.
- Coil Form Factor Advantage: The continuous coil tube configuration enables high-efficiency downstream processing — including automated roll forming, cutting, and welding — with minimal material waste and maximum production throughput.
- Full Traceability & Certification: Every coil is accompanied by complete mill test certificates (MTC), chemical analysis reports, and mechanical test data, ensuring full material traceability from melt to finished product.
Technical Notes
Yield Strength (Rp0.2) is defined as the stress at which a material exhibits a permanent (plastic) deformation of 0.2% of its original length. It is determined by applying a uniaxial tensile load to a standardized test specimen and measuring the engineering stress corresponding to a 0.2% offset from the linear elastic region of the stress-strain curve. For 2205 Duplex Stainless Steel, the dual-phase austenite-ferrite microstructure contributes to enhanced dislocation density and solid-solution strengthening, resulting in the characteristically high yield strength of ≥ 450 MPa.
It is important to note that the yield strength of 2205 Duplex is highly dependent on proper heat treatment. Inadequate solution annealing can lead to δ-ferrite enrichment or σ-phase precipitation, which may embrittle the material and reduce ductility. Wenzhou Jixing Metal Materials Co., Ltd. employs strict thermal processing controls to ensure consistent microstructural balance and mechanical property uniformity across every coil produced.