Cold-drawn alloy steel tubes are precision-engineered tubular products manufactured by drawing hot-rolled alloy steel hollows through a tungsten carbide die and over a precision mandrel at room temperature. This cold-working process delivers strict dimensional accuracy, excellent surface finish, and enhanced mechanical properties compared to hot-rolled alternatives.
Engineered for high-stress industrial applications, our tubes achieve tight dimensional tolerances (down to ±0.05 mm), uniform wall thickness, and tailored metallurgical conditions (as-drawn, stress-relieved, or quenched and tempered).
Specifications
|
Parameter |
Specification Range / Standard |
|
Production Standards |
ASTM A519, EN 10305-1, DIN 2391, JIS G3445 |
|
Steel Grades |
AISI/SAE 4130, 4140, 8620, 52100; 25CrMo4, 42CrMo4, 34CrMo4 |
|
Outer Diameter (OD) |
10 mm - 219 mm |
|
Wall Thickness (WT) |
1.5 mm - 30 mm |
|
Length |
Fixed length or random length (3 m - 12 m) |
|
Delivery Condition |
+C (BK), +LC (BKW), +SR (BKS), +A (GBK), +QT (Q+T) |
Material & Manufacturing
Raw Material Inspection: Incoming hot-rolled alloy round bars undergo ultrasonic testing and chemical composition verification.
Hot Piercing & Shell Preparation: Billets are heated in a rotary hearth furnace and pierced to form seamless hollows.
Surface Preparation: Pickling (acid cleaning) removes scale, followed by phosphating and reactive lubrication to ensure stable friction during cold drawing.
Cold Drawing: Hollows are drawn through tungsten carbide dies and over precision mandrels to achieve target dimensions and strain hardening.
Heat Treatment: Controlled atmosphere furnaces perform annealing, stress relieving, or quenching and tempering to eliminate residual stresses and meet required mechanical properties.
Straightening & Cutting: Multi-roll precision straightening machines ensure straightness within 1 mm/1000 mm, followed by automated cold cutting.
Quality Inspection
Every production lot undergoes rigorous verification prior to dispatch:
Dimensional Verification: Laser micrometers and air gauges check OD, ID, and wall thickness continuously along the tube length.
Non-Destructive Testing (NDT): 100% eddy current testing for longitudinal defects and ultrasonic testing for internal flaws per ASTM E213 / EN 10246-7.
Mechanical Testing: Tensile testing (yield strength, tensile strength, elongation), Rockwell/Brinell hardness testing, and ring flattening or flaring tests per lot.
Metallographic Examination: Grain size, inclusion rating, and decarburization depth analysis via optical microscopy.
Documentation & Third-Party Audit: EN 10204 3.1 Mill Test Certificate (MTC) supplied with every shipment. Third-party inspections by SGS, TÜV, or BV can be accommodated upon request.
Applications
Hydraulic Systems: Precision cylinders and fluid power lines requiring high burst pressure resistance.
Automotive Sector: Drive shafts, steering columns, axle tubes, and fuel injection rails.
Industrial Machinery: Roller bearings, heavy equipment structural components, and high-torque drive components.
Energy Equipment: Downhole drilling tools, pump barrels, and high-pressure piping.
Customization & Supply
Dimensional Customization:
Non-standard outer diameters, specific wall thicknesses, and tight custom tolerances reviewed per engineering drawing.
Length Options:
Precision cut-to-length services with tight length tolerances (±0.5 mm) to minimize downstream machining scrap.
Surface Protection:
Anti-rust oil coating, phosphated exterior, plastic caps on both ends, bundled with steel strapping, and wrapped in woven bags or secured in wooden crates.
Logistics Support:
Flexible MOQ, container loading optimization, and established international freight partnerships.
FAQ
Q: What is the typical lead time for standard vs. custom dimensions?
A: Standard sizes listed in stock or active production schedules require 2 - 3 weeks. Custom dimensions requiring specialized drawing dies or custom heat treatment cycles typically take 4 - 6 weeks.
Q: What is the difference between +C and +SR delivery conditions?
A: +C (BK) represents the as-drawn condition with high yield strength and a bright, cold-drawn surface finish. +SR (BKS) is stress-relieved after cold drawing, which reduces internal residual stresses, improves machinability, and stabilizes mechanical properties.
Q: Can you supply tubes with specific mechanical properties rather than just standard grades?
A: Yes. By controlling chemical composition ranges and applying targeted heat treatment (such as quenching and tempering), we can adjust yield strength, tensile strength, and hardness to match your specific engineering requirements.
Q: What NDT standards do your inspection lines comply with?
A: Our automated testing lines comply with international standards including ASTM E213, EN 10246-7, and ISO 10893, backed by full traceability records.
Q: How do you prevent corrosion during ocean transport?
A: Tubes are internally and externally coated with a specialized moisture-displacing anti-rust oil. Ends are sealed with tight-fitting plastic caps, and bundles are wrapped in moisture-resistant film before being loaded into heavy-duty containers or wooden crates.
Q: What is your minimum order quantity (MOQ) for custom alloy grades?
A: MOQ depends on the steel grade and specific dimension. Generally, custom production runs require a minimum of 3 - 5 metric tons per size to ensure rolling and drawing efficiency.
Request a Quote
Submit your engineering requirements and drawing files to receive a formal technical and commercial quotation within 24 hours.
Required RFQ Information:
• Steel Grade: AISI 4130, 42CrMo4
• Outer Diameter and Wall Thickness: mm or inches
• Delivery Condition: +SR, +QT
• Quantity: Metric tons or total meters
• Destination Port and Target Delivery Schedule
• Attachment: Upload engineering drawing (.PDF / .DWG) for rapid evaluation
Upload Drawing & Request Quote
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