Difference between Cold and Hot rolled sheets

Hot rolling, the process used to make hot rolled steel, involves rolling steel at high temperatures (about 1700˚F). These high temperatures are above steel’s recrystallization temperature, allowing the steel to be easily shaped, formed, and made into larger sizes. As it cools, hot-rolled steel tends to shrink non-uniformly which gives less control over the size and shape of the finished product when compared to cold-rolled steel.

While cold rolled sheets are hot-rolled steel that has been further processed by allowing it to cool at room temperature and annealed or temper rolled. Cold rolling produces steel with closer dimensional tolerances and a wider range of surface finishes than hot rolling. It is also up to 20% stronger than hot rolled through the use of strength hardening.

Hot-rolled steel tends to be cheaper than cold-rolled steel because it is manufactured without any delays in the process and does not require reheating like cold-rolled steel. It is also essential to normalise as it is allowed to cool at room temperature; this means that it is free from internal stresses that can arise from quenching or work-hardening processes. Cold rolled steel typically results in a product with a better, finer surface with closer tolerances. It also yields smoother surfaces that are oily to the touch. It can also be used in precise applications as it is harder and stronger than hot-rolled steel. Its hardness can be increased and it can resist tension breaking. Its pleasing finish with a wider range of surface finish is the highlight of it. 

One of the many differences between hot and cold rolled steel is price. Hot-rolled steel in India tends to be cheaper than cold-rolled steel prices because it is manufactured without any delays in the process and does not require reheating like cold-rolled steel. It can be used in applications where precise shapes and tolerances are not required, such as structural components (Railroad Tracks, I-Beams, Sheet Metal), agricultural pieces of equipment, metal buildings, stampings, and automotive frames.

Cold-rolled steel prices are costlier than hot-rolled and they are used in applications where tolerances, surface conditions, concentricity, and straightness are factors. It also offers a more aesthetic and visually appealing surface. Other applications include home appliances, metal furniture, aerospace structural components, and automotive parts. 

The basic difference between these two types of steel is one of process. Hot rolling refers to processing done with heat. Cold rolling refers to processes done at or near room temperature. Steel of different grades and specifications can be either hot rolled or cold rolled including basic carbon and other alloy steel. If looking for cold-rolled and hot-rolled steel in India, the first name that comes to mind is JSW Steel. Their variety of products and quality had made them the most trusted brand in steel. Do check their website to know more about it.