Cold-Finished is stock that has been rolled at room temperature. During this rolling process, the stock is doused in oil, which keeps the final product unoxidized, keeping the surface smooth and the natural grey color of the actual steel. Hot RollHot Rolled Imageed is formed at much higher temperatures and is not bathed in oil, allowing for more flexibility in forming the metal, but also allowing for greater corrosion.
Most forms of Hot Rolled are more flexible than Cold Finished. While this isn’t usually noticeable in most forms, you can see a difference in some of the smaller sizes. If you are looking for steel with high structural integrity, Cold-Finished might be a better choice.
At the corners and edges, Hot Rolled may appear to be a little rounded, with dimensions that might be less exact than Cold-Finished.