The Difference Between Cold-Finished and Hot-Rolled Steel

Business owners and makers have thousands of steel varieties on the market to choose from. With such an array of metal options, selecting the correct type, grade, and finish of your building material can be tedious. Pennsylvania Steel Co. offers a vast assortment of premium steel products at locations all over the United States. Plus, our online resources help our clients build the best projects possible.

Steel Manufacturing, Summarized

Not to be mistaken with the four main types of steel, the general steel manufacturing process falls into two main categories: hot-rolled and cold-rolled. This process starts with the extreme heating and consequent oxidation of mined steel ore.Basically, pieces of large, rectangular metal called billets are heated and flattened into sizable rolls. 

From there, the steel will go through one of the aforementioned rolling processes for its finalized design. “Rolling” refers to the vital step in the manufacturing process that involves forming the metal by using a series of rollers in an attempt to reshape it or enhance its properties. This formation method (hot or cold rolling) will determine the material’s ultimate function.

Hot Finishing Process vs. Cold Finishing Process

"In the conversation about hot-rolled vs. cold-finished products, all cold-finished products are hot-rolled, but hot-rolled products are not necessarily cold finished. Instead, it’s all a matter of how the bars are processed."

ryerson.com

Once steel is heated past its recrystallization temperature (over 1700º F) it can be easily formed and sized. If the material isn’t processed further at room temperature, it’s considered hot-rolled. The steel that goes through further refinement processes is categorized as cold-rolled. Explore further metal rolling methodology differences, capabilities, and tolerances below!

Hot-Rolled Steel

As hot-rolled steel cools, it tends to shrink and form asymmetrically, allowing for more variation in shape and size. For this reason, hot-rolled steel is used in projects where the finished product doesn’t have specific dimensional requirements.

For example, one of the most commonly recognized forms of hot-rolled steel is sheet metal, which is frequently used in creating air ducts and motor vehicles. In these applications, surface finish and proportions don’t need to be precise.

As a result, hot-rolled steel is typically cheaper in price simply because it doesn’t involve any further processing. Since it doesn’t require any reheating, production costs for hot-rolled steel are much lower.

Cold-Finished Steel

That being said, cold-rolled steel needs reheating to further refine its structural properties. In order to achieve more exact dimensions and surface quality, the metal is re-rolled at a lower temperature. This supplemental rolling results in more specified attributes including exterior finish, durability, and dimensional parameters. 

PA Steel, for example, carries a variety of cold-finished bars in a range of grades and finishes for businesses all over the eastern United States. This equipment is used for creating products such as furniture, garages, and home appliances.

Although it’s typically up to 20% more durable than hot-rolled, cold-finished steel is limited to basic square, round, and flat shapes. Despite its improved resistance, the additional processing performed on cold-rolled metals may make it more susceptible to internal stress. Finalized materials need to be stress relieved prior to grinding or cutting to avoid potentially volatile warping or distortion.

Determining the Appropriate Steel Type

Put simply, the last step in the manufacturing process will influence the final product’s application. If tolerance, surface finish, symmetry, straightness, or aesthetics are a key factor in the project’s creation, cold-rolled steel is likely the ideal choice. Conversely, hot-rolled steel can be used for large-scale or low-budget operations that can account for dimensional changes as it cools.

Tolerance Variety

The table below outlines the varying tolerances of hot-rolled vs. cold-finished steel products:

Data source: rapiddirect.com/blog/hot-rolled-vs-cold-rolled-steel

Premium Steel and Pipe Supply From Pennsylvania Steel, Co.

Visit our new and improved website to browse our selection of high-quality products, including several varieties of cold and hot-rolled steel, plus carbon tubing, stainless steel, finished bars, and more. PA Steel employs an expert team of industry professionals that are prepared to supply you with the ideal metal for any size project. Browse our locations in Pennsylvania, Richmond, Cleveland, Long Island, and more!

If you’re still having trouble figuring out the ideal steel production process for your project, check out our FAQ page or request a quote online today!