Hot-rolled strips and sheets are the steels that have been roll-pressed at very high temperatures over 1,700˚F, which is above the re-crystallization temperature for most steels. This process makes the steel easier to form, which results in products that are easier to work with.
Cold rolled strips and sheets are essentially hot rolled steels that will be processed further. Once the hot rolled steel has been cooled down, it is then re-rolled at the room temperature to achieve precise dimensions with better surface qualities.
Hot Rolled Coils and Cold Rolled Coils
Rolling is a vital process in steel manufacturing, which is widely used for fabricating different applications and techniques. It leads to improve strength and orientation within the steel. In the process of rolling, the steel from large rolls is converted into the steel with the required thickness and shape. There are two types of steel rolling processes: Hot rolling and Cold rolling.
A G Universal Limited is a supplier and manufacturer of high quality Hot Rolled Coils and Cold Rolled Coils in India. We manufacture Hot Rolled Coils and Cold Rolled Coils in different sizes, grades and specification as per international guidelines. We also export our products in many countries.
The complete process of making hot rolled and cold rolled coils is as follows:
- The large rolls of steel are roll-pressed using a very high temperature of more than 1,700˚F to produce hot rolled coils.
- During the processing of hot rolled coils, the manufacturers use a rectangular billet of large size to start the process.
- Once the billet gets heated, manufacturers sent it to pre-process.
- During the pre-processing, the steel is undergoing through a flattening process to generate a hot rolled coil of a large size.
- The hot rolled coil goes through a number of compression stages to get the desired dimensions.
- Once the hot rolled steel starts to cool down, it shrinks gradually. As it is cooled down after processing it is not possible to control the final shape of the product. Hence, it is not suitable for applications that need precision results.
- A hot rolled coil is re-rolled at lower temperature mostly in room temperature once the hot rolled coil has cooled. This helps to achieve more surface qualities with more accurate dimensions.
Hot rolled coils are used in the welding and construction trades to make railroad tracks and I-beams. Hot rolled steel is used when precise shapes and tolerances are not required. Some common examples of usage of hot rolled coils are in the welding, construction of Railroad tracks, I-beams, Agriculture equipment, Stampings, Wheel rims, Water heaters, Strappings, and Truck frames. A hot rolled coil has many benefits for different applications for forming it as per the desired shapes like curved, arched, angled, etc.
Hot rolled coils have following characteristics:
- A scaled surface i.e. a residue of cooling from extreme temperatures
- Slightly rounded edges and corners for bar and plate products
- Slight distortions, where cooling may result in slightly trapezoidal forms, as opposed to perfectly squared angles
Cold rolled coils are used for projects requiring tolerances, surface conditions, concentricity, and straightness. Some examples of usage of cold rolled coils are Home appliances, Metal furniture, Chairs, Tables, Water heaters, Exhaust pipes, Filing cabinets, Shelving products and Aerospace.
Cold rolled coils are identified by the following properties:
- Finished and smooth surfaces
- Square shaped bars with well-defined corners and edges
- Tubes having better uniformity, concentric shape, and straightness
- Harder as it can retain its shape very well