Hot Rolled Steel
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-dip galvanized steel coil can be obtained with a pure zinc coating by the hot-dip galvanizing process. It combines the economy, strength and formability of steel with the corrosion resistance of zinc. The hot dip process is a process of applying a zinc coating to steel to prevent rusting. It is particularly useful for a myriad of outdoor and industrial applications.
Characteristics of hot-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
Cold Rolled Steel
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.
The raw material for cold rolled steel coils is a high quality hot rolled product that has been pickled and continuous rolled, degreased, annealed, flattened, slit, and sizing lines.
When producing more precise shapes, the process involves
Decomposition
Semi-finishing
Sizing
Semi-roughing
Roughing
Finishing
Advantages of Cold Rolled Steel
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
Applications for Cold-Rolled Steel
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