4130 Oval Tubing

Where Oval Tube Is Used

Oval tube has application in bicycle design (top tubes and downtubes where aerodynamic profiling and reduced lateral bending resistance are desired), and in specialist automotive bodywork components. However, these applications typically use aluminium alloy or mild steel, not 4130 chromoly.

For 4130 Requirements

If a design calls for an oval cross-section in 4130, the options are: fabricating from round tube by mechanically flattening (which significantly changes mechanical properties and is not recommended for structural applications); machining from solid bar stock; or reviewing the design to determine whether round tube of equivalent section modulus meets the engineering intent.

Oval and Streamline Sections

The best-known example is streamline tubing for aircraft struts, a teardrop or elongated oval section that reduces drag while carrying wing and landing gear loads. Race cars use similar sections for suspension wishbones exposed to the airflow, and motorcycle and bicycle frames use ovalised tubes to gain stiffness in one plane.

These sections start as round seamless tube and are shaped by rolling or drawing through profiled tooling. Supply is limited to particular sizes, and tooling may be needed for anything unusual, so treat an oval requirement as a special enquiry. Send the major and minor axis dimensions, the wall, the length and the quantity. Small quantities are sometimes better made by the fabricator from round tube, as described under elliptical tubing. The parent material is described under round tubing.