Customers often ask about the differences between hot and cold rolled steel sheet. The fundamental differences between these two types of metal go down to the ways they are processed at the mill, and not the product grade or specification.
Hot rolled steel comes from the mill process that involves rolling the material at a high temperature, usually above 1,700° F. Since the steel is beyond its re-crystallization temperature, you can mold and form it easily, making it possible to create larger sizes.
This manufacturing process is pretty straightforward and doesn’t come with much delay. Because of this, hot rolled is generally more affordable than cold rolled steel where reheating is often required.
Hot rolled will shrink slightly once it cools, giving less control on the shape and size of the finished product. You will often find it at welding and construction trades that make I-beams and railroad tracks, where precise shapes are not a requirement.
This is hot rolled steel that goes through further processing. The steel comes to cold reduction mills, where the metal cools at room temperature followed by annealing and tempers rolling. This additional process creates a type of steel that has a wider range of surface finishes and dimensional tolerances.
Due to its decreased carbon content, cold rolled is easier to work with than hot rolled steel. It also has fewer imperfections and has better tensile strength. Any project where surface condition, straightness, and concentricity are major factors, cold rolled steel is the ideal material to use.
It’s easy to get confused from all these terms, so do your research and don’t hesitate to ask your metal fabrication partner for advice. Be sure to evaluate all the physical and chemical properties you need for your project to find which material will work best.