Within the steel industry, steel tubing and hollow steel bar are some of the most commonly used steel materials for a variety of applications. Both these products, which offer a significant cost advantage to solid metal bar stock while providing similar strength, are offered at Wasatch Steel.
Steel tube and hollow bar may be similar in shape, but they do have a few important differences that you should know before working with either. Here are these basic differences.
Hollow bar can be produced to be extremely homogenous, and can also capture very tight dimensional tolerances. The latter is more difficult with tube, and tube can also create a lower-quality product than is generally desired if the manufacturer is not careful to remove excess metal. This is to avoid stress concentrators in welded tubing.
In addition, tubing should be annealed or heat-treated after welding to ensure the creation of a homogenous product. If welding creates different crystalline structures near the weld zone, this can limit the mechanical properties found in the tubing.
Perhaps the biggest difference between tube and hollow bar is how they’re made. Tube is made by running slit coils of a base metal and running it through a tube mill, which forms it into a given shape. From here, edges are joined together using a weld, generally high frequency welding or electric resistance welding. Finally, excess metal is removed from the outside, and newly joined tubing is usually brought through an annealing process.
Hollow bar requires no welding, however. It can either be created using drilling through a solid bar or through centrifugal casting, which is when molten metal is poured into a round mold that’s rotating at high speeds – the force generated by the spinning mold causes the molten to push to the inside mold wall, where it cools and hardens.
Welded tubing can be created using a wide variety of materials, and hollow bar comes in only just short here. In some cases, harder and stronger materials are more difficult to extrude for hollow bar creation, so a piercing method will be used. The decision between these two usually comes down to the desired application – material type and tolerances need to be considered, and design considerations will come into play also.
Want to learn more about steel tubing and hollow steel bar, or interested in any of our other steel services? The experts at Wasatch Steel are standing by to assist you.