Angle Iron vs. Square Tubing: A Strength Comparison

For just about any project that requires a metal structure, the strength of its framework is one of the first considerations.

Whether you’re building a skyscraper or a car, the framework you create has to stand up to the demands of intended use.

Among the strongest building materials available, angle iron and square tubing are go-to components for creating a framework that’s safe and long lasting.

While both have similar applications, there are key differences in their abilities to withstand stress to keep in mind for your project.

Let’s dive into how angle iron vs. steel square tubing stack up against each other in the strength department.

Angle Iron Strength

Angle iron is one of the most recognizable iron products on the market. Characterized by its L-shape, angle iron components are in almost everything around you. From skyscraper crossbeams to your bed frame or washing machine, you’ll find angle iron.

Because of their shape, angle iron pieces are able to withstand great amounts of pressure.

With a single, 90° bend, angle iron is one of the strongest structural support elements. That’s because it evenly distributes stress along its entire length and resists bending. With only two sides, there’s less of a chance for pressure surrounding a piece to compromise its shape or integrity.

However, with fewer sides offering support, single angle iron beams succumb to torsion more than other structural or mechanical steel components.

Angle Iron Frames: Stronger Together

Angle iron pieces work better together.

That’s why angle iron pieces are almost never used by themselves in any application.

To stave off any twisting, angle iron pieces are fastened together to create a framework. Support structures made with angle iron frames -- whether bolted or welded -- have enhanced cross-sectional integrity. Angle iron frames are nearly impossible to twist regardless of where pressure is coming from.

Square Tubing Strength

Like its L-shaped counterpart, square tubing boasts excellent strength.

It’s often used in the same applications as angle iron, such as:

Building construction
Barriers
Vehicle frames

Square steel tubing’s strength comes from its shape.

Requiring more material to fabricate, square tubes are generally thicker than angle iron or round tubes. Despite requiring more metal to fabricate, its strength-to-weight ratio allows for lighter pieces to hold more weight. That means you can do more with less.

With four uniform sides, square tubing has high tensile strength and stands up to extreme temperatures and pressures. Its shape also resists torsion, splitting, and shrinking.

However, square tubing’s shape is also its source of weakness.

Placed under extreme stress, square tubing’s vertical edges combined with its tension distribution cause pieces to lose strength. This can lead to internal rippling along its 90° bends and other distortions.

Square Tubing: Manufacturing for Strength

To alleviate any concerns with square tube strength, turn to how it’s manufactured.

Though its shape can lead to some issues with strength, square tubes can be made to more than withstand the demands of your project.

Steel tubing of any shape is made in one of two ways: hot or cold forming.

Generally speaking, cold formed steel tubing is stronger. That’s because through strain hardening, it resists bending by up to 20% more than hot formed tubes.

However, hot formed steel tubes can be made stronger than cold formed tubes by adding alloys during processing. Beware: Any impurities within hot formed tubing make pieces susceptible to bending.