321 Ti-Stabilized Austenitic Stainless Steel Coil Tube
Wenzhou Jixing Metal Materials Co., Ltd. presents a premium-grade 321 Ti-stabilized austenitic stainless steel coil tube, engineered for demanding high-temperature industrial applications. This product represents the pinnacle of heat-resistant stainless steel coil tubing technology, offering exceptional resistance to intergranular corrosion in elevated temperature environments ranging from 450°C to 900°C.
Product Overview
The 321 stainless steel coil tube is a titanium-stabilized austenitic alloy designed specifically for applications requiring sustained high-temperature service. By incorporating titanium in a ratio of Ti/C ≥ 5×%C, this alloy effectively prevents chromium carbide precipitation at grain boundaries, thereby maintaining outstanding corrosion resistance even after prolonged exposure to temperatures within the critical sensitization range of 450–900°C. This makes the 321 coil tube the material of choice for high-temperature exhaust systems, power generation equipment, and chemical processing installations where reliability and longevity are paramount.
Material & Properties
The 321 grade stainless steel is a modification of the standard 304 austenitic stainless steel, with titanium added as a stabilizing element. The titanium preferentially combines with carbon to form titanium carbides, preventing the formation of chromium carbides that would otherwise deplete chromium at grain boundaries and lead to intergranular corrosion. Key metallurgical characteristics include:
- Stabilization Ratio: Ti/C ≥ 5×%C, ensuring complete carbon binding and elimination of sensitization risk
- Intergranular Corrosion Resistance: Superior performance in the 450–900°C temperature range where standard 304 grade would suffer severe degradation
- Weldability: Excellent welding characteristics with minimal post-weld sensitization, eliminating the need for stabilizing heat treatment in most applications
- Creep Resistance: Enhanced high-temperature strength and resistance to stress rupture at elevated service temperatures
- Formability: Retains the excellent cold and hot working properties characteristic of the austenitic stainless steel family
- Non-magnetic: Maintains austenitic microstructure throughout normal processing and service conditions
Specifications
| Parameter | Specification |
|---|---|
| Material Grade | ASTM A269 / ASME SA-269 TP321, ASTM A213 / ASME SA-213 T321 |
| Chemical Composition (Typical) | C ≤ 0.08%, Si ≤ 0.75%, Mn ≤ 2.0%, P ≤ 0.045%, S ≤ 0.030%, Cr 17.0–19.0%, Ni 9.0–12.0%, Ti ≥ 5×%C |
| Product Form | Coil Tube (盘管) |
| Classification | Austenitic – Heat Resistant (奥氏体-耐热型) |
| Operating Temperature Range | Up to 900°C (continuous service) |
| Corrosion Resistance Range | Resistant to intergranular corrosion at 450–900°C |
| Outer Diameter Range | Customizable per customer requirements |
| Wall Thickness | Customizable per customer requirements |
| Surface Finish | Pickled & Passivated, Mill Finish |
| Delivery Condition | Annealed (Solution Annealed) |
| Coil Weight | Standard industrial coil packaging |
Manufacturing Process
Wenzhou Jixing Metal Materials Co., Ltd. employs a rigorous multi-stage manufacturing process to ensure the highest quality and dimensional accuracy of every 321 coil tube produced:
- Raw Material Selection: Only certified 321-grade stainless steel billets and slabs from approved mills are procured, with full chemical analysis verification confirming Ti/C ≥ 5×%C compliance.
- Hot Rolling & Annealing: Billets are hot rolled to the required tube dimensions and subsequently annealed to restore full austenitic microstructure and ensure optimal mechanical properties.
- Cold Drawing / Cold Reduction: Tubes are cold worked to achieve precise dimensional tolerances, improved surface finish, and enhanced mechanical strength.
- Solution Annealing: Final annealing at 1010–1150°C followed by rapid cooling to homogenize the microstructure and ensure complete titanium carbide formation.
- Pickling & Passivation: Surface treatment to remove oxide scale and establish a protective chromium oxide passive film for superior corrosion resistance.
- Coil Winding & Inspection: Tubes are precisely coiled to specified diameters and subjected to comprehensive quality inspection prior to packaging.
Applications
The 321 Ti-stabilized stainless steel coil tube is specifically engineered for the following high-temperature and corrosive environments:
- Aerospace Industry: Aircraft exhaust pipes and turbocharger ducts where sustained temperatures of 450–900°C are common and intergranular corrosion resistance is critical for airworthiness certification.
- Power Generation: Boiler headers, superheater tubes, and economizer components in coal-fired, gas-fired, and nuclear power plants operating at elevated temperatures.
- Heat Exchangers: Shell-and-tube heat exchangers, double-pipe heat exchangers, and air preheaters in chemical processing, petrochemical, and oil refining industries.
- Furnace Components: Radiant tubes, convection tubes, and furnace fixtures in industrial heating applications.
- Chemical Processing: Reactor internals, distillation columns, and process piping in environments where both high temperature and oxidizing/corrosive media are present.
- Marine & Offshore: High-temperature exhaust systems and heat recovery units in marine propulsion and offshore platform installations.
Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system and holds the following certifications ensuring product conformity to international standards:
- ISO 9001:2015 — Quality Management System Certification
- ISO 14001 — Environmental Management System Certification
- ASTM / ASME — Material compliance with ASTM A213/A269 and ASME SA-213/SA-269 specifications
- EN 10216-5 — European standard compliance for heat exchanger tubing
- Third-Party Inspection (TPI) — Available upon request for critical applications
- Mill Test Certificates (MTC) — Provided with every shipment, confirming full chemical and mechanical analysis
- NADCAP / Aerospace Quality — Available for aerospace-grade orders
Unique Selling Points
Exceptional High-Temperature Integrity: The Ti/C ≥ 5×%C stabilization ratio provides unmatched resistance to intergranular corrosion throughout the entire 450–900°C sensitization range, dramatically extending component service life in critical applications.
Superior Weldability Without Stabilizing Treatment: Unlike unstabilized austenitic grades, 321 coil tube can be welded in the as-received condition without requiring subsequent stabilizing heat treatment, reducing fabrication costs and production lead times.
Proven Aerospace Heritage: Decades of service in aircraft exhaust systems validate the material's reliability under the most demanding thermal cycling conditions.
Cost-Effective Alternative to Higher Grades: 321 coil tube delivers performance comparable to 310 or 347 grades at a significantly lower material cost, offering optimal value for high-temperature applications.
Flexible Coil Delivery: Delivered in coil form for seamless integration into automated tube processing, forming, and fabrication lines, minimizing waste and maximizing productivity.
Wenzhou Jixing Metal Materials Co., Ltd. is committed to delivering world-class 321 stainless steel coil tube products that meet the exacting standards of global industrial and aerospace sectors. With state-of-the-art manufacturing facilities, rigorous quality control, and dedicated technical support, we are your trusted partner for high-temperature stainless steel tubing solutions.