St52 DIN2391 BK / NBK Precision Seamless Tube

DIN 2391 St52 BK Seamless Cold-Drawn Precision Steel Tube

DIN 2391 St52 BK refers to a high-quality, seamless, cold-drawn precision steel tube made from non-alloy quality steel grade St52 and delivered in the cold-processed (cold-worked) condition

This product is engineered for mechanical and automotive applications where exceptional dimensional accuracy, a superior surface finish, and enhanced mechanical properties are critical. The cold drawing process ensures these tubes outperform standard hot-finished tubes in precision and strength.

Key Features & Advantages

• Superior Dimensional Accuracy: Manufactured to extremely tight tolerances on outside diameter (OD) and wall thickness (WT).

• Excellent Surface Finish: A smooth, scale-free surface ideal for functional components, often requiring no further finishing.

• Enhanced Mechanical Properties: The cold drawing process significantly increases yield and tensile strength, providing excellent structural integrity.

• High Consistency: Guaranteed chemical and mechanical properties ensure reliability and predictability in manufacturing and performance.

• Ready for Machining: The excellent surface and consistent properties make it suitable for further machining and processing.

Material & Chemical Composition

*Note: Silicon content is typically not a major specified element for St52 grade in this standard but can be present in small amounts. The composition is based on DIN 2391-1 and related material standards.

• Mechanical Properties

  The "BK" (cold-processed) condition is the most common delivery state. The cold working (drawing) hardens the material, resulting in significantly higher strength values compared to the normalized state.

  The guaranteed mechanical properties for DIN 2391 St52 BK are:

   

   

  Property	Yield Strength (Rₑ or Rp0.2)	Tensile Strength (Rₘ)	Elongation at Break (A)
  Value	≥ 420 MPa	580 - 740 MPa	≥ 6 %

  These values are minimum guarantees for the cold-drawn condition as per the standard.

  Comparison Note: If the same tube were supplied in the normalized condition ("+N"), its yield strength would be lower (≥ 355 MPa), but its elongation would be much higher (≥ 22%). The "BK" condition is chosen for its higher strength.

  Typical Applications

  DIN 2391 St52 BK tubes are ideal for high-stress structural parts and precision components, such as:

• Hydraulic and Pneumatic Cylinder Tubes: Where precise dimensions and pressure resistance are vital.

• Automobile Parts: Shock absorber cylinders, steering columns, and other chassis components.

• Precision Machinery: Linear motion shafts, guide sleeves, and bearing housings.

• General Mechanical Engineering: For all types of welded and machined constructions requiring high strength.

• Summary

  DIN 2391 St52 BK represents a top-tier seamless cold-drawn tube that combines the strength of St52 steel with the precision of the cold drawing process. It is the material of choice for engineers and designers who require a reliable, high-performance component that offers excellent machinability, dimensional stability, and superior mechanical properties straight from the mill.

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