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You may have heard of both hot- and cold-rolled steel, but do you know the difference between them? If not, we’re here to help.
The Basic Difference
Production of both hot- and cold-rolled steel starts with the same steps. They're both initially processed at extremely high temperatures. However, once the treated steel is ready, cold-rolled steel goes through a few extra steps. The mill lets the metal cool off until it's room temperature, then draws it through rollers or puts it through annealing treatment. This additional labor makes it more expensive than hot-rolled steel.
Visually Telling Them Apart
There are three main visual differences between the two processes. Hot-rolled steel has rounded edges, a rough surface texture, and no grease on its finish. Alternatively, cold-rolled steel has sharp edges, a very smooth surface texture, and an oily or greasy feel to it.
When to Use Hot-Rolled Steel
The pros and cons of hot-rolled steel come down to strength versus price. Hot-rolled steel is weaker than cold-rolled, but it’s also cheaper since it doesn’t go through the second production process. However, this doesn't automatically mean cold is better just because it's stronger and more expensive.
The more significant difference in how to use it is how specific your material needs are. Hot-rolled steel is perfect for welding, railroad tracks, and I-beams because there is less concern for smooth finishes and precise shapes. The tolerance range is also wider because the metal shrinks during the cooling process, so you can't be as exact with the measurements.
While hot-rolled steel has a rougher surface, the aesthetic difference is fixable if that's your only reason for avoiding it. It will add to the total cost, but you can grind or sandblast the steel to a smooth finish.
When to Use Cold-Rolled Steel
Cold-rolled steel is going to cost more, but it may be worth the higher price tag if it fits your needs. You're going to pay for tight tolerance, smooth finish, and consistency between pieces.
So when should you splurge on the higher-cost option? In addition to the visual benefits of a smooth surface, cold-rolled steel is best when you need consistency and tight tolerances on a project. Workers shape the steel at room temperature, so there's no risk of shrinkage during the cooling process. You'll know the exact dimensions you're getting, and every piece is uniform.
As a note, while shopping around for options, sometimes cold-rolled steel is also called cold-finished or cold-drawn steel. These names are particularly common when referring to bars.
In the end, there is no right or wrong answer on which one is better. Both have benefits and drawbacks that make the ideal option change from project to project. Whichever product suits your needs, Industrial Metal Supply is here to help.