Stainless Steel Coil Tube — Elongation & Ductility Performance Specification
Wenzhou Jixing Metal Materials Co., Ltd. delivers premium-grade stainless steel coil tubes engineered for superior plastic deformation capacity. Elongation (A%) serves as the definitive indicator of a coil tube's ability to undergo plastic deformation without fracture — a critical parameter for downstream forming, bending, deep drawing, and mechanical processing operations. Our coil tube products are manufactured to meet or exceed international standards, ensuring reliable performance across the full spectrum of temper conditions.
Product Overview
Stainless steel coil tubes from Wenzhou Jixing Metal Materials Co., Ltd. are continuous-length tubular products wound into coils for efficient handling, storage, and automated processing. These coil tubes are produced from high-quality austenitic and ferritic stainless steel grades, offering excellent corrosion resistance, mechanical strength, and formability. The elongation performance of our coil tubes is meticulously controlled during the cold-drawing and annealing stages, ensuring that each product delivers predictable and consistent ductility characteristics tailored to specific temper requirements.
The elongation percentage (A%) measures the percentage increase in gauge length of a tensile specimen at the point of fracture. A higher elongation value indicates greater ductility and the capacity to absorb energy through plastic deformation — a vital property for applications requiring complex shaping, expansion, and mechanical working.
Material & Mechanical Properties
Elongation (A%) — Plastic Deformation Capability
Elongation is the primary indicator of a material's plastic deformation capacity. Wenzhou Jixing Metal Materials Co., Ltd. guarantees the following minimum elongation values across all temper conditions:
- Soft Temper (Annealed): Elongation ≥ 40% — Maximum ductility for deep drawing, severe bending, and complex forming operations.
- Half-Hard Temper (1/2 Hard): Elongation ≥ 25% — Balanced combination of formability and spring-back resistance for moderate forming applications.
- Hard Temper (Full Hard / Cold-Worked): Elongation ≥ 15% — Enhanced dimensional stability and strength for applications requiring minimal post-forming deformation.
Complementary Mechanical Properties
- Tensile Strength: Varies by grade and temper condition; typically 520–750 MPa for austenitic grades (e.g., 304, 316).
- Yield Strength: Generally 205–620 MPa depending on temper and grade.
- Hardenability: Austenitic grades exhibit excellent cold-work hardening response, enabling controlled property enhancement through mechanical working.
- Toughness: Superior low-temperature impact resistance, maintaining ductility even at cryogenic temperatures.
Specifications
| Parameter | Soft Temper | Half-Hard Temper | Hard Temper |
|---|---|---|---|
| Elongation (A%) — Minimum | ≥ 40% | ≥ 25% | ≥ 15% |
| Typical Tensile Strength | 520–620 MPa | 620–720 MPa | 690–750 MPa |
| Typical Yield Strength | 205–310 MPa | 345–520 MPa | 485–620 MPa |
| Applicable Grades | 304, 304L, 316, 316L, 321, 310S | 304, 304L, 316, 316L, 321, 310S | 304, 304L, 316, 316L, 321, 310S |
| Outer Diameter Range | Φ3.0 – Φ50.0 mm | Φ3.0 – Φ50.0 mm | Φ3.0 – Φ50.0 mm |
| Wall Thickness Range | 0.3 – 3.0 mm | 0.3 – 3.0 mm | 0.3 – 3.0 mm |
| Coil Length | Custom (typically 30–100 m) | Custom (typically 30–100 m) | Custom (typically 30–100 m) |
| Surface Finish | Ba & Pickle / Brushed / Polished | Ba & Pickle / Brushed / Polished | Ba & Pickle / Brushed / Polished |
Manufacturing Process
Step 1: Raw Material Selection
Only certified stainless steel strip or rod from reputable mills is used as feedstock. Incoming materials undergo rigorous spectroscopic analysis (OES) to verify chemical composition compliance with ASTM, EN, or JIS standards.
Step 2: Cold Drawing & Forming
Continuous cold-drawing equipment with precision-die tooling shapes the stainless steel into the desired coil tube geometry. The cold-drawing process induces controlled work hardening, which is subsequently managed through temper selection to achieve target elongation values.
3: Intermediate Annealing (Where Required)
For soft temper products, intermediate annealing at controlled temperatures (typically 1050–1150°C) restores full ductility by recrystallizing the deformed microstructure, achieving elongation values ≥ 40%.
Step 4: Temper Conditioning
Final temper condition is achieved through controlled cold-work reduction or partial annealing:
- Soft Temper: Full solution annealing + controlled cooling.
- Half-Hard Temper: Partial cold-work reduction (40–60% reduction) without full recrystallization.
- Hard Temper: Maximum cold-work reduction (60–80%+) to maximize strength while maintaining ≥ 15% elongation.
Step 5: Surface Treatment & Finishing
Coil tubes undergo pickling and passivation to remove surface oxides and contaminants, ensuring optimal corrosion resistance and surface integrity. Additional surface treatments (brushing, polishing) are available upon request.
Step 6: Quality Inspection & Testing
Every production lot undergoes comprehensive testing including:
- Tensile testing (per ASTM A370 / ISO 6892) to verify elongation (A%) compliance.
- Chemical analysis (OES / wet chemistry) for grade verification.
- Dimensional inspection (OD, wall thickness, straightness).
- Surface quality examination (visual + magnetic particle testing where applicable).
- Hydrostatic or pneumatic pressure testing for leak integrity.
Step 7: Coiling, Packaging & Dispatch
Finished coil tubes are wound onto standard or custom spools, wrapped in protective film, and packed in export-grade wooden crates or steel drums to prevent surface damage during transit.
Applications
Wenzhou Jixing Metal Materials Co., Ltd. stainless steel coil tubes with verified elongation performance are widely utilized across diverse industries:
Soft Temper (Elongation ≥ 40%)
- Deep-drawn food processing equipment components (dairy, beverage, pharmaceutical).
- Automotive exhaust system forming and expansion.
- Medical device manufacturing requiring complex geometries.
- Ornamental and architectural applications with intricate bending requirements.
Half-Hard Temper (Elongation ≥ 25%)
- Heat exchanger coils and condenser tubing.
- Fluid conveying systems in chemical and petrochemical plants.
- Spring-loaded components and mechanical assemblies.
- Industrial gas piping requiring moderate forming.
Hard Temper (Elongation ≥ 15%)
- High-pressure hydraulic and pneumatic tubing.
- Precision instrumentation and sensor housings.
- Automotive fuel lines and brake lines.
- Structural components requiring dimensional stability and high yield strength.
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains rigorous quality management systems and produces coil tubes in accordance with the following international standards:
- ISO 9001:2015 — Quality Management System Certification.
- ISO 14001:2015 — Environmental Management System Certification.
- ASTM A554 / A555 — Standard specifications for seamless stainless steel tubing.
- ASTM A376 — Standard specification for cold-drawn seamless stainless steel tubing.
- ASTM A370 / ISO 6892 — Mechanical testing methods (tensile, elongation verification).
- EN 10217 / EN 10216 — European standards for seamless stainless steel tubes.
- JIS G3459 / G3460 — Japanese Industrial Standards for stainless steel tubing.
- GB/T 14976 / GB/T 13296 — Chinese national standards for stainless steel tubes.
Testing & Traceability
Each coil tube shipment is accompanied by a full Mill Test Certificate (MTC) documenting chemical composition, mechanical properties (including elongation A%), heat treatment records, and dimensional data. Full lot traceability is maintained from raw material receipt through final dispatch, ensuring complete accountability and compliance verification.
Key Selling Points
- Guaranteed Elongation Performance: Industry-leading minimum elongation values (≥40% soft, ≥25% half-hard, ≥15% hard) verified through ASTM/ISO-standard tensile testing on every production lot.
- Multi-Temper Availability: Single-source supplier for all three temper conditions, enabling streamlined procurement and consistent quality across product lines.
- Wide Grade & Size Range: Comprehensive portfolio covering austenitic, ferritic, and duplex stainless steel grades in OD from Φ3.0 mm to Φ50.0 mm.
- Continuous Coil Format: Eliminates butt welds, reduces material waste, and enables high-speed automated processing in downstream manufacturing.
- Full Traceability: Complete documentation from mill certificate to shipment, supporting regulatory compliance in food, pharmaceutical, and aerospace sectors.
- Customization Capability: Non-standard dimensions, surface finishes, and temper conditions available upon request to meet specific application requirements.
Note: All elongation values stated above represent guaranteed minimums under standard test conditions (23°C ± 2°C, standard gauge length). Actual performance may exceed stated minimums depending on grade, dimensions, and manufacturing batch. For application-specific elongation requirements, contact Wenzhou Jixing Metal Materials Co., Ltd. technical team for detailed consultation and custom testing protocols.