Round steel tube is used in a variety of industries. It is primarily good for applications that need good structural and mechanical support. But what else do you need to know about round steel tubing?
For starters, round steel tube comes in a wide assortment of outside diameters, wall thicknesses and lengths.
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Round Steel Tubing: Seamless
Piercing and rotating a heated red hot solid metal bar through the center of the tube produces a seamless tube (or pipe).
One thing to keep in mind with seamless round steel tubing is that the cost for parts produced from these products can be very competitive due to the high rate of metal displacement when compared to other forging processes.
Depending on the final part configuration, seamless mechanical tubing is often the most economical method of manufacturing.
Hot Finished Seamless and
, Cold Drawn Seamless
Produced from grades 1026 and 4140, hot finished seamless (HFSM) steel tubing can be made to specification ASTM 519. HFSM is furnished in as-rolled, no subsequent thermal treatment, or finishing, and to specific OD and ID wall dimensions.
Produced from 1026 hot-rolled stock, cold drawn seamless (CDSM) steel tubing can be made to ASTM 519 and produced to OD and ID dimensions. This product offers better surface quality, dimensional accuracy, and mechanical properties compared to hot finished.
Round Steel Tubing: Welded
ERW (electric resistance welded)
ERW is typically produced from low carbon steel grades 1008 or 1010. This product offers good forming qualities and is not typically suited for highly engineered applications.
The process involves slitting a coil to width, which will form into the desired tube diameter through a series of rolls and a welded process. From there, the coil thicknesses will form the final wall thickness of the tube.
Flat rolled steel is fed through forming rolls which force the strip into a cylinder. Each forming roll pushes the strip a small amount until it is converted into the desired tubular shape. The edges of the strip are then electric resistance welded.
This process can often create a “flash” which is the steel that extrudes (melts through) the seam of an electric resistance welded tubular. Flash may be present on the outside as well as the inside of tubulars. The flash curl generated during the welding process is coherent and will not flake off.
OD flash should be removed to provide a smooth, consistent surface.
The welding process of ERW produces variations in hardness between the welded seam and the rest of the tube. If the ERW tube is to be cold drawn, it must first be heated to a suitable uniform temperature above the transformation range and cooled in air to a temperature below the transformation range; this is called normalizing.
DOM (drawn over mandrel)
Improve surface finish and dimensional accuracy while enhancing mechanical properties with DOM. This is a cold-drawn process in which the tubing is drawn through a die and over a mandrel.
The benefits of DOM round steel tubing include:
- Close tolerances
- High yield and tensile strength
- Superior surface finish
- Excellent concentricity
- Manufactured to an almost infinite range of OD and wall thickness dimensions
D.O.M. (Welded) A-513-Type 5
· Carbon 1020: 10 ga. (typically .134 wall) and lighter
· Carbon 1026, ST52.3 & 4130 (typically .135 wall and heavier)
· Typically produced to OD/ID dimensions
D.O.M. (Welded) A-513-Type 6 (SSID)
· Special Smooth Inside Diameter
· Typical grades ST52.3 and 1026
Round Steel Tubing: Value Add
As with any steel product, round steel tubing can be enhanced through additional processing. For round steel tubing, this includes saw cutting, deburring, drilling, and laser cutting.
Check out all the benefits of a tube laser: