You can already tell what some of the obvious differences are between hot rolled and cold rolled steel. What you may not have known is that there are also significant differences between cold rolled steel and cold rolled steel sheet metal. You would think that the processes and production for both would be the same, since they are "cold" products. Yet, the opposite is true. Here are their differences, why it matters, and why not all "cold" metal products are the same.
Cold Rolled Steel Is Much Thicker
Cold rolled steel is much thicker than the sheet metal product. The mill took hot rolled steel and cooled it at room temperature for hours to get cold rolled steel. Then one of five main processes are used to process this steel further than the hot rolled steel will ever be processed. After the rolled steel has been cooled, it may also go through a grinding process, a cold drawing process, a turning process (which is essentially sanding away imperfections while the metal is processed on a turning table or industrial lathe), and/or a polishing process where it is made smooth and shiny.
As for the sheet metal, the sheet metal is rolled through flattening and grinding machines until it is just a sheet a few millimeters thick. Cold rolled steel itself can be up to an inch or slightly thicker. The sheet metal is intentionally made thinner so that it can be easily cut, punched, hammered, or milled in dozens of other ways to suit your needs. The sheet metal may also be burnished and polished, but these milling processes are not often used or requested because of the expected or intended use of the sheet metal.
Cold Rolled Has a Higher Carbon Content
Cold rolled steel has a higher carbon content. That really does not mean much unless you understand that it makes cold rolled more difficult to work with and less malleable than sheet metal. The sheet metal has a lower carbon content, which makes it ideal for forming, bending, twisting, and wrapping.
On the one hand, you would want cold rolled in place of hot rolled so that you can use the cold rolled for things that need a tougher, stronger and more durable metal. On the other hand, you cannot bend or shape cold rolled in the same way as the cold sheet metal. It helps to understand that the carbon content, which is what makes diamonds hard, is the reason why you can do some things with the cold rolled that you cannot do with the cold sheet metal, and vice versa.
Rolled Is Rolled and Flat Sheet Is Flat Sheet-Not!
Steel products come through a mill with some misnomers. Cold rolled is cold rolled because it is rolled flat for annealing and cooling processes. It is then cut into bars or left as-is in slab formation. Sheet metal is most commonly left in a flat sheet form, but if it has been fully processed, it can be rolled onto rollers and stored this way. Ergo, cold rolled steel is more often flat slabs, while the sheet metal may actually be stored in rolls. Make sure you know the difference so that when you place an order for steel, you order the correct "cold" metal product.
Numerous Other Steel Products
Now that you understand some differences between cold rolled steel and steel sheet metal, it is unlikely that you will get these products confused in the future. Their applications are as different as their formations are. If you are not entirely certain of what you need, reach out to a professional at a place like A & C Metals - Sawing. they should be able to provide you with more specifics.