Not all steelmaking processes involve heating steel to or above its recrystallization temperature. Cold rolling, for example, is performed at room temperature. Not surprisingly, it requires greater pressure to roll and form steel at room temperature. Because cold-rolled steel is manipulated well below the recrystallization temperature of steel, however, it offers several benefits. Below are some of the top benefits of cold-rolled steel.
Increased Strength
Cold-rolled steel is significantly stronger than hot-rolled steel. As the rollers compress the steel at room temperature, the steel becomes stronger due to strain hardening. Just how strong is cold-rolled steel exactly? Although there are exceptions, cold-rolled steel is typically about 20% stronger than its hot-rolled counterpart.
Improved Surface Finish
In addition to being stronger, cold-rolled steel has an improved surface finish. It’s smoother and has fewer surface imperfections than hot-rolled steel. Not only does this improve the aesthetics of cold-rolled steel; it makes cold-rolled steel a more suitable material for certain applications, such as the construction of bridges.
Tighter Tolerances
Cold rolling allows for tighter tolerances than hot rolling. What does this mean exactly? In metalworking, the term “tolerance” refers to the overall thickness of metal. Cold-rolled steel is typically thinner — without sacrificing strength — than hot-rolled steel. As a result, cold rolling offers tighter tolerances than aren’t found in other steelmaking processes.
Multiple Options
There are several different options available for creating cold-rolled steel, some of which include full-hard, half-hard, quarter-hard and skin-rolled. Of all those options, full-hard cold rolling is often preferred because it offers the tightest tolerances. When performed correctly, full-hard cold rolling can reduce the thickness of steel by up to 50%. Other cold rolling processes can also reduce the thickness of steel, but they aren’t as effective as full-hard cold rolling.
What Are the Disadvantages of Cold-Rolled Steel?
As you can see, cold-rolled steel offers several benefits, some of which include increased strength, improved surface finish, tighter tolerances and multiple options. But there are still a few disadvantages associated with cold-rolled steel. When compared to hot-rolled steel, cold-rolled steel typically costs more money to produce. For many metalworking companies, this makes hot rolling a more attractive process.
Another disadvantage of cold-rolled steel is its low malleability. It’s easier to deform and manipulate the shape of hot-rolled steel because the process requires heating steel to or above its recrystallization temperature. Cold rolling, however, involves compressing steel under rollers at room temperature, thereby making it more difficult to shape.