What is the difference between hot rolled steel and cold rolled steel?
There are many types of steel based on different types, grades, specifications, finishing and other processing considerations. However, it is the type of steel made in terms of rolling, which is the production method: Hot rolled steels and Cold rolled steels.
Understanding the differences between hot and cold rolled steel enables designers and engineers to achieve better results. Consequently, this situation also affects the costs.
There are many types of steel in various shapes, grades, specifications, finishing and other process aspects. The key difference between prefab steel products is the difference between hot rolled and cold rolled steel.
It may seem obvious, but some types of steel are better suited for certain applications than others. Knowing which to use can help you avoid spending more on raw materials than necessary. It can also save time and money in additional processing. In other words, understanding the differences between hot and cold rolled steel enables designers and engineers to achieve better results and at the best possible price.
The main difference between hot rolled steel and cold rolled steel types is one of the processes. As you can imagine, “hot rolling” refers to operations when the steel is hot. “Cold rolling” refers to operations performed at or near room temperature. Although these techniques affect the overall performance and application, they should not be confused with the official specifications and steel grades regarding metallurgical structure and performance ratings. Steels of different grades and properties can be hot rolled or cold rolled, including basic carbon and other alloy steels.
Hot Rolled Steel
To process hot rolled steel, manufacturers start with a large rectangular slab, or slab. The slab is heated and pretreated, where it is flattened with a large roll, or rollers. From there, it is brought to high temperatures and hot steel is made in the form of a core, passed through a series of compression rollers to bring it to the desired thickness and width, this process is called rolling. For Coil, Steel producers wrap rolled steel in coils and let it cool. They can be produced in other forms such as Steel Profile and steel strip, steel plates.
As Slab Steel cools, its expansion comes back and its width narrows. Hot rolled steel is cooled to room temperature after processing, it is not suitable for sensitive applications. Hot rolled steel is generally not used for precision consumption as they are thick materials – for example in railway tracks and construction projects.
Hot rolled steel requires much less processing as a structure than cold rolled steel, making it much cheaper than cold rolled steel. The hot rolled steel is cooled at room temperature and normalized, that is, it is free from internal stresses that may arise during hardening processes.
We know that hot rolled steel, thickness and width tolerances are not precise compared to cold rolled steels. Hot rolled steels are more ideal in the absence of surface coating. If a better surface quality is desired, the surface structure can be corrected by grinding, sandblasting or acid bath, ie surface cleaning. Descaled steel also offers a better surface for galvanizing, which is paint and other surface coatings.
Cold Rolled Steel
Cold rolled steel is actually hot rolled steel that has undergone further processing. To obtain cold rolled steel, steelmakers buy Hot rolled steel. For the production of cold rolled steel from hot rolled steel, it performs more rolling to obtain more precise dimensions and better surface quality.
Technically, “cold rolled” applies only to steel sheets that are compressed between Steel rolls. However, forms such as profiles or logs are “Pull”, that is, they are not simply passed between the rollers. Thus, hot rolled profiles and billets, once cooled, cannot be formed again.
Having better surface properties than hot rolled steel, it is not surprising that cold rolled steel is used more often for technically delicate applications or where aesthetics are important. However, they are sold at a higher price than hot rolled steels due to the number of operations and costs for cold rolling.
Cold rolled steels are sensitive to their physical properties, the cold rolling process can also create internal stresses within the material steel. In other words, fabricating cold rolled steel – whether by cutting, bending, or welded structures – can release stresses and cause unpredictable fracture or cracking.