What is Hot Rolled Steel?
It is a type of steel that is formed using the hot rolling process at a temperature above its recrystallization temperature. Steel is easier to shape at this elevated temperature. Compared to cold rolled steel, hot rolled typically does not require any post-forming heat treatment. Hot rolled usually has more mill scale than cold rolled steel.
To process, manufacturers start with a large, rectangular billet. The billet gets heated and sent for pre-processing, where it is flattened into a large roll. From there, it is kept at a high temperature, and the glowing white-hot steel is run through a series of compression rollers to achieve its finished dimensions. For sheet metal, manufacturers spin the rolled steel into coils and leave it to cool. For other forms, such as bars and plates, materials are sectioned and packaged.
Steel shrinks slightly as it cools. Because hot rolled steel is cooled after processing, there is less control over its final shape, making it less suitable for precision applications. Hot rolled steel is often used when minutely specific dimensions aren’t crucial—in railroad tracks and construction projects, for example.
Hot rolled can often be identified by the following characteristics:
- Scaled surfaces, the remnants of cooling from extreme temperatures.
- Slightly rounded edges and corners for bar and plate products (due to shrinkage and less precise finishing).
- Slight distortions, where cooling may leave slightly trapezoidal forms rather than perfectly squared angles.
Hot Rolled Steel for Construction
Hot-rolled steel is commonly used to form steel beams and columns on construction projects. They are created by passing heated steel between large rollers, which deform it into the required shape, such as; H, I, W, S, C, angles, tubes, and so on.
Because the creation typically requires much less processing than cold rolled steel, which makes it a lot cheaper and because it is allowed to cool at room temperature, it’s essentially normalized—meaning it’s free from internal stresses that can arise from quenching or work-hardening processes.