Cold finished（Soft）Pipe&Tube

The manufacturing process involves cold drawing operations or cold rolling processes followed by precise low-temperature stress relieving at 400-600°C, significantly lower than full annealing temperatures. This controlled thermal treatment eliminates partial residual stresses from cold working while preserving the refined microstructure achieved through cold deformation, unlike complete annealing which reconstructs the metallic structure.

These BKW condition pipes demonstrate enhanced plasticity compared to hard condition tubes, with elongation rates improved to 15%-25% depending on material grade. The substantial stress reduction enables reliable performance in medium-difficulty forming operations including bending, flaring, and flanging without cracking concerns. Meanwhile, they maintain dimensional accuracy comparable to BK tubes, with excellent stability in outer diameter/wall thickness tolerances and surface roughness typically within Ra≤1.6μm, requiring no secondary processing for assembly.

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The balanced mechanical properties of Cold Finished Steel Pipes (BKW/+LC) show tensile strength between hard and fully annealed conditions, such as 350-480MPa for St35 material grades. This optimal balance preserves partial cold-working strengthening effects while ensuring better processability than BK tubes, achieving the perfect combination of precision and manufacturability. The superior surface quality remains unaffected by low-temperature annealing in protective atmospheres, presenting clean, smooth surfaces without oxide scale.

Technical Advantages:

  • Optimized balance between precision and processability

  • Enhanced plasticity with elongation 15%-25%

  • Maintained dimensional accuracy and surface quality

  • Preserved partial cold-working strengthening effects

  • Reduced residual stresses without microstructural reconstruction

  • Immediate usability for medium-forming operations

These stress-relieved cold-finished tubes serve effectively in hydraulic and pneumatic systems for medium-low pressure hydraulic lines, cylinder barrels, and pneumatic connectors requiring both precision and minor bending/assembly capabilities. The mechanical manufacturing industry utilizes these pipes for precision components requiring subsequent machining, welding, or forming, such as shaft sleeves, gear blanks, and small brackets where hard condition tubes might crack during processing.

The automotive and household appliance sectors employ these BKW/+LC condition tubes for small-diameter oil pipes and fluid conduits in air conditioning and compressor systems where precision and assembly convenience are equally important. General precision applications benefit from these tubes in scenarios requiring dimensional accuracy with simple secondary processing like flaring or threading, offering higher efficiency than GBK tubes and better processability than BK condition pipes.

Supported by Tianzhan’s 21 years of seamless tube specialization and 30 years of technical expertise in our R&D team, we provide customized BKW/+LC solutions tailored to your specific application requirements. Our advanced manufacturing capabilities ensure each Cold Finished Steel Pipe (BKW/+LC Condition) meets exact specifications for materials, dimensions, surface quality, and mechanical properties, delivering reliable performance for applications demanding both precision and moderate formability.