Half-Hard (1/2H) Stainless Steel Coil Tube — Medium Cold Worked Temper
Product Overview
Wenzhou Jixing Metal Materials Co., Ltd. offers premium-grade Half-Hard (1/2H) Stainless Steel Coil Tubes, engineered through controlled medium cold working to deliver an optimal balance between mechanical strength and formability. This temper condition is achieved by applying a moderate degree of cold reduction to annealed stainless steel tubing, resulting in enhanced yield strength, superior pressure resistance, and maintained ductility — making it the ideal choice for applications demanding both structural integrity and moderate forming capability.
The 1/2H temper represents a critical midpoint in the stainless steel tube temper spectrum, positioned between fully annealed (soft) and fully hard (H) conditions. This intermediate state provides engineers with a versatile material solution that resists deformation under operating loads while still permitting controlled bending, flaring, and shaping during fabrication.
Material & Properties
Temper Characteristics
- Temper Designation: Half-Hard (1/2H) — Medium Cold Worked
- Hardness Range: HV 220–280 (Vickers)
- Elongation at Break: ≥20%
- Yield Strength: Significantly elevated compared to annealed (soft) condition
- Tensile Strength: Enhanced through work hardening effects
- Springback: Moderate — requires consideration in precision forming operations
Key Mechanical Behavior
The medium cold working process introduces dislocation density within the austenitic or ferritic grain structure, creating a strengthened matrix that resists plastic deformation under service loads. The resulting HV 220–280 hardness range provides improved pressure resistance, making these tubes particularly suitable for fluid conveying systems, hydraulic circuits, and pressurized process lines where wall integrity is paramount.
Important Note: Due to the elevated hardness and reduced ductility compared to the fully annealed condition, bending operations on 1/2H coil tubes require a larger minimum bending radius to prevent cracking, surface wrinkling, or thinning at the bend apex. Proper forming parameters must be calculated based on tube diameter, wall thickness, and alloy grade.
Specifications
| Parameter | Specification | Notes |
|---|---|---|
| Product Name | Coil Tube (盘管) | Supplied in coil form for downstream processing |
| Temper Condition | Half-Hard (1/2H) | Medium cold worked temper |
| Hardness | HV 220–280 | Vickers hardness, measured per ASTM E92 |
| Elongation | ≥20% | Adequate ductility for moderate forming |
| Pressure Resistance | Enhanced | Superior to soft/annealed condition |
| Bending Requirement | Larger minimum bend radius | Must account for reduced ductility vs. annealed |
| Product Classification | Product Specifications — Mechanical State | Series No. 49 |
| Supplier | Wenzhou Jixing Metal Materials Co., Ltd. | Manufactured to international quality standards |
Comparison with Other Tempers
| Temper | Hardness (HV) | Elongation | Formability | Pressure Resistance |
|---|---|---|---|---|
| Soft (Annealed) | ~130–170 | ≥40% | Excellent | Standard |
| Half-Hard (1/2H) | 220–280 | ≥20% | Good | Enhanced |
| Hard (H) | ~300–350+ | ≤15% | Limited | Maximum |
Manufacturing Process
Production Workflow
- Material Selection: High-purity stainless steel billets or strip are selected based on alloy grade (e.g., 304, 316L, 321) and intended application requirements.
- Tube Forming: Seamless tubes are drawn through calibrated dies or welded tubes are formed from precision strip, establishing the base coil tube geometry.
- Full Annealing: Tubes are solution-annealed at elevated temperatures (typically 1050–1150°C) followed by controlled cooling to establish a fully soft, recrystallized microstructure.
- Medium Cold Working (Key Step): The annealed tubes undergo controlled cold reduction — either through sizing/drawing or controlled coiling — to achieve the 1/2H temper. The degree of deformation is precisely calibrated to produce HV 220–280 hardness while maintaining ≥20% elongation.
- Surface Finishing: Tubes receive final surface treatment (pickling, passivation) to ensure corrosion resistance and clean surface integrity.
- Coiling & Packaging: Finished tubes are coiled at controlled tension to prevent deformation, then packaged for shipment.
Process Control
- Reduction ratio is monitored to ensure consistent hardness across the coil length
- Hardness verification performed at multiple points along the coil
- Temperature control maintained during annealing to prevent grain overgrowth
- Residual stress management to prevent springback issues during customer forming operations
Applications
The Half-Hard (1/2H) temper coil tube finds extensive application across multiple industries where enhanced mechanical properties are required without sacrificing all formability:
Primary Applications
- Automotive Industry: Fuel lines, brake lines, exhaust components, and air conditioning refrigerant tubes requiring moderate forming and elevated pressure resistance
- Hydraulic & Pneumatic Systems: Hydraulic hose sleeves, pneumatic tubing, and high-pressure fluid conveyance lines
- Oil & Gas: Downhole tubing components, injection lines, and wellhead connections operating under sustained pressure
- Medical Devices: Endoscope tubing, surgical instrument housings, and medical gas delivery systems requiring corrosion resistance and dimensional stability
- Food & Beverage Processing: Sanitary piping, milk processing lines, and beverage transfer systems under moderate pressure
- Construction & Architecture: Structural decorative tubes, handrails, and facade elements requiring improved strength for load-bearing applications
- Electronics & Appliances: Heat exchanger tubes, refrigeration coils, and appliance structural components
Ideal Use Cases
The 1/2H condition is particularly advantageous when:
- Operating pressures exceed the capacity of soft/annealed tubing
- Moderate bending or shaping is required during fabrication (not complex deep draws)
- Dimensional stability under thermal cycling is important
- Resistance to indentation and mechanical damage during service is a priority
Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd. maintains rigorous quality assurance protocols ensuring every coil tube lot meets international standards:
- ISO 9001:2015 — Quality Management System certification ensuring consistent production quality
- ISO 14001 — Environmental Management System for sustainable manufacturing practices
- Material Certifications: EN 10204 3.1 material test certificates provided with each shipment
- Compliance Standards: Product specifications aligned with ASTM A269, ASTM A554, EN 10216, and JIS G3446
- Non-Destructive Testing: Eddy current testing (per ASTM E709) and hydrostatic pressure testing performed on all production lots
- Mechanical Verification: Hardness testing (Vickers), tensile testing, and elongation verification per ASTM E8
- Traceability: Full batch traceability from raw material mill certificates through final inspection
Unique Selling Points
- Optimized Strength-Formability Balance: The 1/2H temper provides a 30–50% improvement in pressure resistance over annealed tubing while retaining sufficient ductility (≥20%) for practical fabrication
- Precise Hardness Control: Tight HV 220–280 range ensures consistent performance across the entire coil length, reducing variability in end-product quality
- Coil Supply Advantage: Delivered in coil form to maximize material utilization and minimize cutting waste in high-volume manufacturing
- Multi-Grade Availability: Available in common austenitic grades (304, 304L, 316, 316L) and duplex stainless steels to suit diverse corrosion environments
- Established Manufacturing Expertise: Wenzhou Jixing Metal Materials brings extensive industry experience in temper-controlled stainless steel tube production, ensuring reliable, repeatable quality
- Customer-Centric Technical Support: Technical guidance provided on forming parameters, minimum bend radii, and application-specific temper selection