321 Austenitic Heat-Resistant Stainless Steel Coil Tube — Wenzhou Jixing Metal Materials
Product Overview
The 321 Stainless Steel Coil Tube from Wenzhou Jixing Metal Materials Co., Ltd is a premium austenitic heat-resistant alloy tubing product engineered for demanding high-temperature industrial environments. As part of our comprehensive materials and metallurgy product line, this coil tube is specifically designed for applications requiring exceptional resistance to intergranular corrosion and sustained thermal exposure in the range of 450°C to 900°C (842°F to 1652°F). The continuous coil form factor offers superior material utilization, reduced cutting waste, and streamlined downstream fabrication compared to straight-length alternatives.
Material & Properties
Grade 321 stainless steel is a titanium-stabilized austenitic chromium-nickel alloy. The addition of titanium (Ti) serves as a potent carbide scavenger, effectively binding carbon atoms and preventing the formation of chromium-depleted zones at grain boundaries — the primary mechanism behind intergranular corrosion in unstabilized austenitic grades such as 304 or 304L.
Key Metallurgical Characteristics
- Stabilization Ratio: Ti/C ≥ 5 × %C — ensures complete carbon scavenging and long-term microstructural stability
- Microstructure: Fully austenitic, non-magnetic, with excellent ductility and formability
- Corrosion Resistance: Superior resistance to intergranular corrosion in the sensitization range of 450–900°C (842–1652°F), where conventional 304/316 grades are vulnerable
- High-Temperature Oxidation Resistance: Maintains structural integrity and surface quality under prolonged thermal cycling
- Creep Strength: Adequate tensile and creep properties for sustained service at elevated temperatures
- Weldability: Excellent weldability without risk of sensitization in the heat-affected zone (HAZ)
Chemical Composition (Typical)
| Element | Specification (wt%) |
|---|---|
| Carbon (C) | ≤ 0.08 |
| Chromium (Cr) | 17.00 – 19.00 |
| Nickel (Ni) | 9.00 – 12.00 |
| Titanium (Ti) | ≥ 5 × %C, minimum 0.30 |
| Manganese (Mn) | ≤ 2.00 |
| Silicon (Si) | ≤ 1.00 |
| Phosphorus (P) | ≤ 0.045 |
| Sulfur (S) | ≤ 0.030 |
| Iron (Fe) | Balance |
Mechanical Properties (Annealed Condition)
| Property | Value |
|---|---|
| Tensile Strength (Rm) | ≥ 515 MPa (74,700 psi) |
| Yield Strength (Rp0.2) | ≥ 205 MPa (29,700 psi) |
| Elongation (%A5) | ≥ 40% |
| Hardness (HBW) | ≤ 201 |
| Density | 8.00 g/cm³ (0.289 lb/in³) |
| Thermal Conductivity (100°C) | 16.3 W/(m·K) |
| Maximum Continuous Service Temperature | 870°C (1598°F) |
| Intergranular Corrosion Resistance Range | 450 – 900°C (842 – 1652°F) |
Specifications
| Parameter | Specification |
|---|---|
| Material Grade | 321 / UNS S32100 / 1.4541 (Ti-stabilized austenitic) |
| Product Form | Coil Tube (continuous coil configuration) |
| Manufacturing Method | Seamless (EN 10216-5 / ASTM A213) or welded (ASTM A554) |
| Outer Diameter (OD) | 6.00 mm – 219.00 mm (0.24" – 8.62") |
| Wall Thickness | 0.50 mm – 12.00 mm (0.020" – 0.472") |
| Coil Inner Diameter (ID) | 300 mm – 1200 mm (11.8" – 47.2") |
| Coil Length | Customized per order (typically 50 m – 200 m) |
| Surface Finish | 2B, BA, No. 4, No. 8, or custom |
| Tolerance (OD) | ± 0.05 mm – ± 0.15 mm (per EN 10216-5) |
| Tolerance (Wall) | ± 10% of nominal |
| Heat Treatment | Solution annealed and water/quench cooled |
| Standards | ASTM A213/A213M, EN 10216-5, GB/T 14976, JIS G3458 |
Manufacturing Process
The production of 321 stainless steel coil tube at Wenzhou Jixing Metal Materials follows a rigorous multi-stage process to ensure dimensional accuracy, metallurgical integrity, and surface quality:
- Raw Material Selection: High-purity titanium-stabilized 321 stainless steel billets or strip are sourced from certified mills with full traceability documentation.
- Hot Rolling / Piercing: Billets are heated to approximately 1150–1200°C (2092–2192°F) and pierced or hot-rolled into seamless tube blanks with controlled wall thickness.
- Heat Treatment: Tubes undergo solution annealing at 1050–1100°C (1922–2012°F) followed by rapid quenching to dissolve titanium carbides uniformly and restore full austenitic structure.
- Cold Drawing / Rolling: Cold working to achieve precise final dimensions (OD, wall thickness) with tight tolerances suitable for coil winding.
- Pickling & Passivation: Acid pickling removes scale and oxide layers; passivation forms a stable chromium oxide film for enhanced corrosion resistance.
- Surface Finishing: Mechanical polishing or electropolishing to achieve the specified surface grade (2B, BA, No. 4, etc.).
- Quality Inspection: Non-destructive testing (eddy current, hydrostatic pressure test), dimensional verification, and chemical/spectrographic analysis.
- Coil Winding & Packaging: Tubes are wound onto precision steel cores with protective packaging to prevent mechanical damage during transport.
Applications
The exceptional intergranular corrosion resistance and high-temperature stability of 321 coil tube make it the material of choice for the following demanding applications:
- Aerospace — Aircraft Exhaust Systems: Withstands extreme thermal cycling and exhaust gas environments without grain boundary degradation. The coil form enables efficient forming of complex exhaust manifold geometries.
- Power Generation — Boiler Headers & Superheaters: Resists sensitization during repeated heating and cooling cycles in high-pressure steam systems, ensuring long service life and reduced maintenance.
- Process Industry — Heat Exchangers: Maintains metallurgical integrity in high-temperature heat exchange applications where temperature fluctuations fall within the 450–900°C sensitization range.
- Petrochemical — Furnace Tubes & Process Piping: Suitable for furnace tube assemblies and high-temperature process lines in refineries and chemical plants.
- Food & Pharmaceutical — High-Temperature Processing Equipment: Meets sanitary requirements while resisting corrosion in aggressive cleaning and sterilization cycles.
- Automotive — Turbocharger Components & Catalytic Converter Housings: Provides durability under sustained high-temperature exhaust conditions.
Unique Selling Points
- Superior Intergranular Corrosion Resistance: Ti/C ≥ 5×%C stabilization ratio provides unmatched protection against sensitization in the critical 450–900°C range — a decisive advantage over 304L in high-temperature service.
- Coil Form Efficiency: Continuous coil delivery minimizes cutting waste (up to 15–20% material savings vs. straight lengths), reduces handling costs, and accelerates downstream fabrication.
- Full Traceability: Every coil is accompanied by a mill test certificate with complete chemical composition, mechanical properties, and heat number traceability.
- Customizable Specifications: Flexible OD, wall thickness, surface finish, and coil dimensions tailored to specific customer requirements.
- Multi-Standard Compliance: Manufactured to meet ASTM, EN, GB, and JIS standards, ensuring global project compatibility.
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd maintains a comprehensive quality management system and holds the following certifications and complies with the following international standards:
- ISO 9001:2015 — Quality Management System certification
- ISO 14001 — Environmental Management System
- EN 10204 Type 3.1 — Mill Test Certificates with independent inspection
- ASTM A213 / A213M — Standard specification for austenitic stainless steel seamless tubing
- EN 10216-5 — European specification for austenitic stainless steel tubes for heat exchange and similar purposes
- GB/T 14976 — Chinese national standard for seamless stainless steel tubes for cold-rolled and cold-drawn applications
- JIS G3458 — Japanese Industrial Standard for austenitic stainless steel seamless tubes
Wenzhou Jixing Metal Materials Co., Ltd is committed to delivering premium-grade 321 stainless steel coil tube with guaranteed metallurgical performance, dimensional precision, and full documentation traceability — meeting the most demanding requirements of aerospace, power generation, and process industry customers worldwide.