Cold-drawn seamless steel pipe is a type of seamless steel pipe produced through a cold drawing process. It uses hot-rolled seamless steel pipe or extruded pipe as the billet. At room temperature, it is pulled through a series of dies to achieve a finished pipe with higher requirements for outer diameter, wall thickness, dimensional accuracy, and surface quality. Because its production process does not involve heating, it is called "cold-drawn."
The typical process flow is as follows:
1. Billet Preparation: Selection of qualified hot-rolled or extruded seamless steel pipe as the billet.
2. Pretreatment: Includes pickling (to remove oxide scale), phosphating, and saponification. Phosphating and saponification are crucial as they form a lubricating layer on the pipe surface, reducing friction during drawing and protecting the dies and pipe surface.
3. Cold Drawing: At room temperature, the pretreated pipe blank is pulled through a die smaller than its outer diameter (or simultaneously using a mandrel to control the inner diameter) under significant tensile force. This causes plastic deformation, achieving diameter reduction, wall thinning, shaping, and improvement of properties. Multiple drawing passes may be required depending on product specifications.
4. Intermediate Heat Treatment: Between multiple drawing passes, stress relief annealing or recrystallization annealing is necessary to eliminate work hardening and restore metal plasticity.
5. Finishing and Processing: After drawing to the target size, straightening, cutting ends, sampling, and inspection are performed.
6. Final Heat Treatment: Depending on product standards and technical requirements, final annealing, normalizing, or quenching and tempering may be conducted to obtain the desired microstructure and properties.
7. Inspection and Warehousing: Final inspection of dimensions, surface, mechanical properties, non-destructive testing (e.g., ultrasonic), etc., is performed. Qualified products are then warehoused.
High Precision: Dimensional accuracy of outer diameter, wall thickness, and inner diameter is far superior to that of hot-rolled pipes.
Excellent Surface Quality: High surface smoothness, low roughness, and free of oxide layer.
Superior Mechanical Properties: The cold working hardening effect provides higher strength, hardness, and fatigue resistance.
Diverse Shapes: Can produce not only round pipes but also various special-shaped cross-section pipes.
Thinner Walls: Capable of producing small-diameter precision pipes with very thin walls.
Limitations: Presence of residual stress, relatively lower toughness; longer production cycle, higher cost; single piece length is limited by equipment.
Due to its high precision, high strength, and excellent surface, cold-drawn seamless steel pipe is widely used in fields with demanding material performance requirements:
The price of cold-drawn seamless steel pipe is not fixed and fluctuates significantly due to various factors. It is usually quoted per ton or per meter. Main influencing factors include:
Raw Material Cost: Market price of the steel itself (e.g., 20#, 45#, alloy steels).
Specifications and Dimensions: The more non-standard the diameter and wall thickness, and the higher the precision requirement, the higher the price.
Material and Grade: Ordinary carbon steel (e.g., 20#) is lower in price; alloy steels (e.g., 40Cr, 42CrMo), stainless steel, etc., are significantly more expensive.
Process Requirements: Heat treatment condition (annealed, normalized, quenched & tempered), surface treatment, special inspections (e.g., ultrasonic, eddy current testing) increase costs.
Market Supply/Demand and Order Quantity: Bulk purchases usually offer better unit prices.
Example Reference (Current general market range, please refer to real-time quotes):
(Important Note: These are volatile market reference prices. Specific procurement must involve obtaining detailed quotes from multiple suppliers.)
Define Purpose and Technical Requirements: First, determine the application, required pressure, torque, wear resistance, and precision requirements for mating components.
Determine Material: Select the appropriate steel grade (e.g., 20#, 45#, 40Cr, stainless steel) and heat treatment state based on mechanical properties, corrosion resistance, working temperature, etc.
Specify Precise Specifications: Provide precise outer diameter, wall thickness, length, and tolerance ranges. The advantage of cold-drawn pipes lies in precision, so clear labeling is essential.
Focus on Surface and Internal Quality: Specify surface finish, allowable minor scratches, etc., based on application requirements. For critical pressure-bearing parts, specify non-destructive testing grades (e.g., Ultrasonic Testing UT).
Supplier Evaluation: Evaluate the supplier's production equipment, technical capabilities, testing methods, and industry reputation.
"Best" is relative and depends on your specific needs (material, specifications, purchase volume, region, budget, etc.). The following are recognized leading manufacturer types and representatives (not constituting specific recommendations):
Top Domestic Large Steel Groups:
Specialized Precision Steel Pipe Producers: Numerous specialized cold-drawn/cold-rolled precision steel pipe factories are clustered in the Yangtze River Delta (e.g., Wuxi, Suzhou), Pearl River Delta, and Shandong. They focus on small and medium-diameter high-precision pipes, offering high flexibility and quick service response. When selecting, focus on their production history, technical expertise, and customer cases.
Internationally Renowned Manufacturers:These companies offer technologically leading products, but prices are usually very high, with long lead times. They are often used in cutting-edge fields with extreme material requirements.
Selection Advice:
In summary, cold-drawn seamless steel tube is a high-performance material distinguished by its excellent dimensional accuracy, superior surface finish, and enhanced mechanical properties achieved through a specialized cold-working process. Its selection hinges on a clear understanding of application requirements, precise specifications, and material properties. If you need to purchase cold-drawn seamless steel pipe, you can contact us, and we can assist you.
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