Consisting primarily of iron and carbon, as well as trace amounts of other elements, steel is alloy metal that’s used in countless manufacturing applications. You’ll find cars, airplanes, ships, buildings, tools and more made of it. There are different classifications of steel, however, including hot rolled and cold rolled. So, what’s the difference between cold-rolled and hot-rolled steel?
Hot-Rolled Steel Explained
Hot-rolled steel is steel that’s produced using extreme heat. The terms “hot-rolled steel” and “cold-rolled steel” don’t refer to a specific type of steel. Rather, they refer to the way in which steel is produced. With hot rolling, molten steel is pressed at extremely high temperatures, typically reaching or exceeding 1,700 degrees Fahrenheit. This is important because steel recrystallizes at roughly 750 degrees to 1,300 degrees Fahrenheit, allowing it to be reshaped. Once the hot-rolled steel has cooled, it’s ready for use (or to sell).
Cold-Rolled Steel Explained
Cold-rolled steel is still exposed to the same high temperatures as hot-rolled steel, and it’s also pressed in the very same way. The difference between the two is that cold-rolled steel undergoes an additional processing step after it has been hot rolled. To make cold-rolled steel, hot-rolled steel is transported to a mill where it’s cooled to room temperature and then re-pressed using rollers.
Statistics show that cold-rolled steel is about 20% stronger than its hot-rolled counterpart. During the cold-rolling process, steel is compressed to achieve a lower density but higher tensile strength. The end result is a stronger metal that’s better suited for high-stress applications than hot-rolled steel.
Cold-rolled steel is also more ductile than hot-rolled steel. In other words, it can bend under greater stress without breaking. With cold-rolled steel being more ductile than hot-rolled steel, manufacturers can work with it more easily, manipulating the metal’s shape to fit their needs.
You can expect hot-rolled steel to cost less than cold-rolled steel. Since cold-rolled steel requires an extra step in its production process, companies must use more resources to make it. Therefore, they generally charge more for cold-rolled steel than hot-rolled steel.
In conclusion, hot-rolled steel and cold-rolled steel are similar in that they both involve a production technique in which steel is exposed to high temperatures and then pressed. Only cold-rolled steel, however, undergoes the additional step of being pressed at room temperature. It’s a minor step when compared to the entire steel production process, but it increases the metal’s strength as well as ductility.