Stainless Steel Coil Tube – Half-Hard (1/2H) Condition | Moderate Cold Worked
Product Overview
The Stainless Steel Coil Tube in the Half-Hard (1/2H) condition, manufactured by Wenzhou Jixing Metal Materials Co., Ltd., represents a precision-engineered intermediate cold-worked product designed to deliver an optimal balance between mechanical strength and ductility. This grade is produced through controlled moderate cold working (moderate cold rolling), positioning it between the annealed (soft, full-annealed) and full-hard (full cold-worked) states in the mechanical property spectrum.
The 1/2H temper condition is achieved by applying a defined degree of plastic deformation to the initially annealed stainless steel tube coil, inducing strain hardening (work hardening) to enhance tensile strength and hardness while retaining sufficient elongation for secondary forming operations. This condition is particularly valued in applications demanding elevated pressure resistance without the brittleness associated with fully cold-worked materials.
Material & Mechanical Properties
The Half-Hard (1/2H) condition is characterized by the following key mechanical properties, which distinguish it from both fully annealed (soft) and fully cold-worked (hard) conditions:
- Vickers Hardness (HV): 220–280 — indicating a significantly enhanced hardness level compared to the annealed state (typically HV 150–200), providing improved resistance to deformation under load.
- Elongation (A, %): ≥ 20% — ensuring adequate ductility for forming, bending, and fabrication processes without premature fracture.
- Pressure Resistance: Substantially improved compared to the annealed condition, making this temper ideal for pressurized fluid and gas conveying applications.
- Bending Characteristics: Requires a larger minimum bending radius than the annealed condition due to the elevated hardness and reduced formability. Proper tooling and technique must be employed during bending operations to avoid cracking or wall thinning.
Specifications
| Parameter | Specification / Value | Notes |
|---|---|---|
| Product Name | Stainless Steel Coil Tube (盘管) | Supplied in coil configuration for downstream processing |
| Mechanical Condition | Half-Hard (1/2H) | Moderate cold working temper |
| Vickers Hardness (HV) | 220 – 280 | Measured per ASTM E92 / ISO 6507 |
| Elongation (A) | ≥ 20% | Ensures adequate ductility for forming |
| Cold Working Degree | Moderate (Intermediate) | Between annealed (0%) and full-hard (~100%) |
| Pressure Resistance | Enhanced | Superior to annealed condition |
| Bending Radius | Larger than annealed condition required | Tooling adjustments necessary |
| Product Category | Product Specification – Mechanical Condition | Classification No. 49 |
| Manufacturer | Wenzhou Jixing Metal Materials Co., Ltd. | — |
Manufacturing Process
The production of Half-Hard (1/2H) stainless steel coil tubes involves a precisely controlled sequence of metallurgical and forming operations:
- Raw Material Preparation: High-purity stainless steel wire rod or strip is selected and subjected to incoming material inspection for chemical composition and dimensional conformity.
- Tube Forming: The raw material is processed through piercing, drawing, or cold-rolled forming operations to establish the initial tube geometry.
- Full Annealing: The formed tubes undergo a complete solution annealing (stress relief annealing) at elevated temperatures (typically 1000–1150°C for austenitic grades) to restore full ductility and eliminate prior work-hardening effects.
- Moderate Cold Rolling / Drawing (Work Hardening): The annealed tubes are subjected to a precisely calibrated degree of cold deformation — typically in the range of 30–50% cold reduction — to achieve the target Half-Hard (1/2H) temper. This is the critical process step that establishes the HV 220–280 hardness range and maintains elongation ≥ 20%.
- Intermediate Annealing (if required): In multi-pass cold working sequences, intermediate annealing steps may be inserted to prevent excessive strain accumulation and maintain formability.
- Coiling: The finished tubes are wound onto coils of specified inner diameter and width for efficient downstream handling and processing.
- Final Inspection & Testing: Hardness testing (HV), tensile testing (elongation verification), dimensional inspection, and surface quality assessment are performed to ensure compliance with the 1/2H specification.
Applications
The Half-Hard (1/2H) temper condition is specifically selected for applications where enhanced mechanical strength and pressure resistance are required while maintaining reasonable formability. Key application areas include:
- Hydraulic and Pneumatic Systems: Tubes for hydraulic lines, pneumatic circuits, and fluid power systems where elevated burst pressure resistance is critical.
- Automotive Industry: Fuel lines, brake lines, and exhaust system components requiring durability under cyclic pressure loading.
- Food and Beverage Processing: Sanitary process tubing in dairy, brewing, and beverage industries where moderate pressure resistance and corrosion resistance are both required.
- Medical Devices: Tubing for medical gas delivery systems, dialysis equipment, and endoscope channels requiring controlled mechanical properties.
- Chemical Processing: Transfer lines and reactor components in chemical plants where the combination of corrosion resistance and pressure resistance is essential.
- Construction and Architecture: Structural decorative tubes, handrails, and balustrade systems requiring improved rigidity and resistance to deformation.
- Heat Exchanger and Boiler Components: Tubing in heat exchanger bundles and boiler applications where moderate pressure resistance and thermal stability are required.
Quality Certifications & Standards
Wenzhou Jixing Metal Materials Co., Ltd. adheres to stringent international quality management and product standards to ensure consistent delivery of Half-Hard (1/2H) stainless steel coil tubes:
- ISO 9001:2015 — Quality Management System certification ensuring consistent production quality and process control.
- ISO 3834 — Quality requirements for welding of metallic materials (applicable to downstream welded assemblies).
- ASTM / ASME Standards — Product compliance with relevant ASTM (American Society for Testing and Materials) and ASME (American Society of Mechanical Engineers) specifications for stainless steel tubing.
- EN / DIN Standards — Conformity with European and German industrial standards for stainless steel tube dimensions and mechanical properties.
- JIS Standards — Japanese Industrial Standards compliance for international market supply.
- Material Testing: Each batch undergoes verified hardness testing (per ASTM E92 / ISO 6507), tensile testing (per ASTM E8 / ISO 6892), and chemical analysis (per ASTM E415 / ISO 3575) to confirm 1/2H temper compliance.
- Mill Test Certificates (MTC): Full material traceability documentation provided with each shipment, including heat number, chemical composition, mechanical test results, and dimensional verification.
Unique Selling Points
Optimal Strength-to-Ductility Balance: The Half-Hard (1/2H) condition delivers a superior combination of enhanced pressure resistance (HV 220–280) and retained formability (elongation ≥ 20%), making it the ideal intermediate temper for applications that cannot tolerate the brittleness of full-hard materials but require more strength than the annealed condition provides.
Precision Cold Working Control: Wenzhou Jixing Metal Materials Co., Ltd. employs advanced process monitoring and control systems to ensure consistent and repeatable cold reduction rates, guaranteeing uniform mechanical properties across entire production batches.
Enhanced Pressure Resistance: The moderate cold working process significantly improves the tube's ability to withstand internal pressure loads, reducing the risk of deformation or failure in pressurized applications.
Coil Format Advantage: Supplied in coil configuration, this product enables seamless integration into automated downstream processing lines, minimizing material waste and maximizing production efficiency for high-volume fabrication operations.
Processing & Handling Notes
- Bending: Due to the elevated hardness of the 1/2H condition, bending operations require a larger minimum bending radius compared to annealed (soft) tubes. Insufficient bending radius may result in cracking, excessive wall thinning, or springback. Adequate tooling and, in some cases, local annealing of bend zones are recommended.
- Cutting: Standard cutting methods (shearing, sawing, laser cutting) are applicable. Sharp tooling is recommended to minimize burr formation and surface damage on the hardened material.
- Welding: Pre-weld annealing of the weld zone is recommended to restore ductility and prevent cracking. Post-weld stress relief may be necessary for critical applications.
- Storage: Coils should be stored in a dry, ventilated environment on appropriate coil supports to prevent deformation and surface corrosion. Avoid direct contact with carbon steel to prevent galvanic corrosion.