Cold rolled steel coil is essentially hot rolled steel that has undergone further processing. Once hot rolled steel has cooled, it is then passed through the rollers again at room temperature. In order to achieve more exact dimensions and better surface qualities.
Cold “rolled” steel is often used to describe a range of finishing processes, though technically, “cold rolled” applies only to sheets that undergo compression between rollers. However, forms like tubes or bars are “drawn,” not rolled. So hot rolled tubes and bars, once cooled, are processed into what are called “cold finished” tubes and bars. Other cold finishing processes include polishing, grinding and turning. Each of which is used to modify existing hot rolled stock into more refined products.
Cold rolled steel can often be identified by the following characteristics:
- Tubes have better concentric uniformity and straightness
- Smooth surfaces that are often oily to the touch
- Better more finished surfaces with closer tolerances
- Bars are of proper dimensions and have well-defined edges and corners
With better surface properties than hot rolled steel, it is often used for more technically precise applications or where aesthetics are important. However, due to the additional processing cold finished products come at a higher price.
In terms of physical characteristics, cold rolled steels are typically harder and stronger than hot rolled steels. As the metal is shaped at the lower temperatures resistance against deformation, resistance against tension breaking, and the steel’s hardness are all raised due to hardening.
These additional treatments, however, can create internal stress within the material. This can result in unpredictable warping if the steel is not stress relieved prior to welding, grinding, or cutting.
Depending on what you are looking to create, each material has its own benefits and drawbacks. For unique projects or one-off productions, prefabricated steel materials can provide the key elements for any structural configuration imaginable.
For projects where you will be mass-producing units, casting is another option that can save time in machining and assembly. Cast parts can be created to form in a range of quality materials.