Cold-Drawn Cold-Rolled Seamless Steel Pipe

Seamless Cold-Drawn or Cold-Rolled Steel Tubes for Precision Applications

High precision cold drawn seamless steel tube identifies the precision steel pipe with high dimension precision (inside diameter and outside diameter), good surface finish, excellent roundness and straightness, and uniform wall occurrence. It can be very popular in mechanical structure and hydraulic gym equipment. This cold rolled or cold drawn seamless steel tube can greatly lessen machining time, improve cling utilization rate and raise the product excellence.

Length of Cold-Rolled Precision Steel Pipe

  • General length is between 2000 mm to 7000 millimeters.
  • The fixed length and multiple length of cold drawn seamless steel tube in order to be controlled above the general length range. The allowable deviation of total length end up being in accordance with the next rules:
  • 1) For precision steel pipes with the space of similar to or when compared with 5000 mm, the deviation should be within 0 to +5 mm.
  • 2) For cold drawn seamless steel tubes with the space of far more than 5000 mm, the deviation should be between 0 to +10 mm.
  • For your delivered precision steel pipes with multiple lengths, really should leave notch margin much like the following regulations:
  • 1) For pipes with the outer layer diameter of equal to or compared to 159 mm, the notch should be within a few mm.
  • 2) For cold drawn seamless steel tubes with the side diameter in excess of than 159 mm, it will be between 10 to fifteen mm.

Curvature (Tortuosity)

Once this precision steel pipe is due to cold finished (hard) state (BK state) or in cold finished (soft) state (BKW state), the curvature should not exceed as well as more.0 mm/m.
When cold drawn seamless steel tube will be cold finished and stress-relieved state (BKS), annealed state (GBK) or normalized state (NBK), the tortuosity donrrrt want to exceed i.5 mm/m.

Weight

  • Delivery weight of such precision steel pipe should meet the kind of specifications. The density of steel is 7.8 5kg/dm3.
  • Can certainly deliver cold drawn seamless steel tubes with theoretical weight subject to the buyer's requirements. This may be negotiated between 2 parties and specified within contract. The tolerance of actual delivery weight and theoretical weight should go along with the following requirements:
  • 1) The tolerance of each precision steel pipe must be within -8% to +10%.
  • 2) The tolerance of cold drawn seamless steel tubes with the batch weight of 10 tons reaches least ±7.5%

Attentions

  • Steel inner and outer surfaces should be smooth. Localized pit, scratch and small scratch shall not exceed the depth of 7.08 mm. The actual thickness of precision steel pipes with those flaws shouldn't be smaller compared to the allowable minimum deviation of wall thickness.
  • Other defects along the inner and outer surfaces of cold drawn seamless steel tubes can be removed by appropriate models. After removal, the actual wall thickness should not really less then an allowed minimum thickness difference.
  • For your inside and outside surfaces of precision steel pipes delivered in cold-finished state, phosphate and lubricant adhesion layer are permitted to carry on.
  • For that inside and outside surfaces of cold drawn seamless steel tubes delivered in heat treatment state, oxide film is allowed to exist mainly because it does not influence leading inspection, but loose oxide scale or oxide skin is prohibited.

Parameters of Cold-Rolled Precision Steel Pipe

Mechanical Properties

Grade Delivery Status
BK BKW BKS GBK NBK
Tensile Strength (MPa) EAF (%) Tensile Strength (MPa) EAF (%) Tensile Strength (MPa) EAF (%) Tensile Strength (MPa) EAF (%) Tensile Strength (MPa) Yield Point (MPa) EAF (%)
Not less than
10 410 6 375 10 335 12   24 335 205 24
20 510 5 450 8 430 10 390 20 410 245 20
35 590 4 550 6 520 8 510 17 530 315 17
45 645 4 630 5 610 7 590 14 600 355 14
Note:
1. EAF means the elongation after fracture.
2. For the cold drawn seamless steel tube with the outside diameter of not more than 30 mm and wall thickness of more than 3 mm, the minimum yield point can reduce 10MPa.

 

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