Stainless Steel Coil Tube — Half Hard (1/2H) Condition
Product Overview
The Stainless Steel Coil Tube in Half Hard (1/2H) temper represents an intermediate mechanical state achieved through controlled moderate cold working (moderate cold reduction). Manufactured by Wenzhou Jixing Metal Materials Co., Ltd., this product series delivers an optimized balance between strength and ductility, making it suitable for applications demanding enhanced pressure resistance while retaining sufficient formability for secondary shaping operations.
The 1/2H temper condition is obtained by cold drawing or cold rolling the annealed (soft) coil tube to a controlled degree of deformation, introducing work hardening (strain hardening) without reaching the full-hard state. This results in a material that exhibits significantly improved mechanical properties compared to the fully annealed condition while preserving adequate elongation for subsequent forming processes.
Material & Properties
The Half Hard (1/2H) stainless steel coil tube is characterized by the following key mechanical and metallurgical properties:
- Hardness (HV): 220–280 — indicating a moderate level of work hardening achieved through controlled cold deformation, providing improved wear resistance and dimensional stability.
- Elongation (A50.8): ≥20% — ensuring sufficient ductility for post-forming operations such as bending, flanging, and stamping within appropriate geometric parameters.
- Pressure Resistance: Enhanced compared to fully annealed condition due to increased yield strength from cold work hardening, making the tube more resistant to internal pressure loading.
- Grain Structure: Elongated grains with increased dislocation density resulting from moderate plastic deformation, contributing to the improved strength-to-ductility ratio.
Specifications
| Parameter | Specification | Standard / Reference |
|---|---|---|
| Product Type | Stainless Steel Coil Tube (盘管) | — |
| Temper Condition | Half Hard (1/2H) | AISI / ASTM Designation |
| Cold Working Degree | Moderate Cold Reduction | — |
| Vickers Hardness (HV) | 220 – 280 | ISO 6507 / ASTM E92 |
| Elongation at Break | ≥ 20% | ASTM A370 |
| Pressure Resistance | Enhanced (vs. Annealed) | — |
| Bending Radius Requirement | Requires Larger Minimum Bending Radius | — |
| Typical Grades | 304 / 304L / 316 / 316L / 321 | ASTM A554 / A580 / EN 10216-5 |
Manufacturing Process
The production of Half Hard (1/2H) stainless steel coil tube involves a carefully controlled sequence of manufacturing steps:
- Hot Rolling & Annealing: Raw stainless steel strip is hot rolled to approximate dimensions and subsequently annealed to achieve a fully soft (A condition) state with uniform austenitic microstructure.
- Forming (Pipe/Tube Making): The annealed strip is formed into a tubular shape via ERW (Electric Resistance Welding), seamless piercing, or spiral welding methods, depending on the target dimensions.
- Intermediate Annealing: A controlled solution annealing treatment restores ductility prior to cold working, ensuring uniform starting conditions for the deformation process.
- Moderate Cold Drawing / Cold Rolling (1/2H): The tube is passed through calibrated dies or rolls with a controlled reduction ratio (typically 15–35% cross-sectional area reduction), introducing the desired degree of strain hardening to achieve the 1/2H temper. This is the critical step that establishes the HV 220–280 hardness range and ≥20% elongation.
- Coiling: The cold-worked tube is wound into coils of specified outer diameter for efficient storage and downstream processing.
- Quality Inspection: Final products undergo hardness testing, tensile testing, dimensional verification, and surface inspection to confirm compliance with specification requirements.
Applications
The Half Hard (1/2H) temper condition is selected when a balance of elevated strength and retained formability is required. Key application areas include:
- Automotive Industry: Exhaust system components, fuel lines, and structural tubing requiring moderate pressure resistance.
- Appliance Manufacturing: Refrigerator tubing, water heater elements, and dishwasher components where dimensional stability is critical.
- Fluid Conveyance Systems: Hydraulic lines, pneumatic tubing, and process piping operating under moderate internal pressures.
- Mechanical Engineering: Precision shafts, guide tubes, and structural components requiring improved spring back resistance.
- Medical Devices: Instrumentation tubing and endoscope sheaths where controlled stiffness and corrosion resistance are essential.
- Food & Beverage Industry: Sanitary process tubing and CIP (Clean-in-Place) compatible lines.
Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd. adheres to international quality management and product standards to ensure consistent performance:
- ISO 9001: Quality Management System certification ensuring systematic control over manufacturing processes.
- ASTM / AISI Standards: Product compliance with American Society for Testing and Materials specifications for stainless steel tubing (e.g., ASTM A554, ASTM A580).
- EN / DIN Standards: European standard compliance (e.g., EN 10216-5) for seamless and welded stainless steel tubes.
- Material Test Reports (MTR): Each batch is accompanied by a full material traceability report documenting chemical composition, mechanical properties, and heat treatment history.
- Third-Party Inspection: Available upon request — including SGS, BV, or TÜV verification of mechanical properties and dimensional accuracy.
Unique Selling Points
The Half Hard (1/2H) condition from Wenzhou Jixing Metal Materials Co., Ltd. offers a superior strength-to-formability ratio compared to fully annealed tube, with enhanced pressure resistance ideal for demanding fluid conveyance and structural applications. The controlled moderate cold working process ensures consistent HV 220–280 hardness across the entire coil, providing reliable batch-to-batch reproducibility. Combined with comprehensive quality documentation and adherence to international standards, this product delivers dependable performance for OEM manufacturers and industrial processors requiring predictable mechanical behavior in downstream forming operations.