The main difference between hot rolled steel and cold rolled steel is the way they are processed. Hot rolled steel is steel that has been rolled at high temperatures, while cold rolled steel is essentially hot rolled steel that has been further processed in a cold rolled material. Here, the material is cooled and then annealed and/or tempered and rolled. Different grades and sizes of steel can be hot-rolled or cold-rolled. Understanding the differences between hot-rolled and cold-rolled steel can help you determine the type that best suits your needs.
Hot rolling is the process used to make hot-rolled steel and involves rolling the steel at high temperatures, usually over 1700°F. These high temperatures are above the recrystallization temperature of the steel. These high temperatures are above the steel's recrystallization temperature, making the steel easy to shape, form and manufacture into larger sizes. As it cools, hot-rolled steel tends to shrink unevenly, providing less control over the size and shape of the finished product than cold-rolled steel.
Hot rolled steel tends to have a scaly surface that can be removed by pickling, grinding or sandblasting. This steel is essentially normalized, which means there are no internal stresses due to quenching or work-hardening processes, as it can be cooled at room temperature. Other properties may include
Hot-Dipped Galvanized Steel Coil
Slightly rounded edges and corners of the plate product (due to shrinkage and less precise finishing)
More ductile and can be turned into a variety of shapes
Increased ductility and toughness
Hot-rolled steel tends to be cheaper than cold-rolled steel because it is manufactured without any delay and does not require reheating as cold-rolled steel does. It is also largely normalized because it can be cooled at room temperature; this means that it has no internal stresses due to quenching or work-hardening processes.
Hot rolled steel tends to be cheaper than cold rolled steel because it is manufactured without any delay and does not need to be reheated as cold rolled steel does. It can be used in applications where precise shapes and tolerances are not required, such as
Structural components (railroad tracks, I-beams, sheet metal)
Cold Rolled Steel Coils
Cold-rolled steel is essentially hot-rolled steel that is further processed by cooling and annealing or temper rolling at room temperature. Cold-rolled steel is produced with tighter dimensional tolerances and a wider range of surface finishes than hot-rolled. It is also 20% stronger than hot-rolled through the use of strength hardening.
When producing more precise shapes, the process involves
Cold rolled steel typically results in a better, shinier surface and tighter tolerances. It can also produce a smoother surface that is greasy to the touch. Other advantages include
Can be used for precision applications
Harder and stronger than hot-rolled steel
Improved hardness, tensile strength and resistance to work-hardening deformation
Aesthetic finishes with a wider range of surface finishes
Cold rolled steel is used in applications where tolerances, surface conditions, concentricity and straightness are influential factors. It also provides a more aesthetically pleasing and visually appealing surface. Other applications include
Aerospace structural parts