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What Is the Difference Between Hot Rolled vs Cold Rolled Steel?

In short, hot rolled steel is processed at the mill at high temperatures and that’s it. On the other hand, cold rolled steel is processed as hot roll, but once it has cooled to room temperature, it received additional processing for different benefits.

Generally speaking, hot roll steel has a rougher surface, wider tolerances, and lower cost. It is used most commonly for construction, welding, and other projects where tight tolerances and exceptional finishes are not necessary. By comparison, cold roll steel has a smoother surface finish, higher strength, and tighter tolerances. Cold rolled steel is superior if tight tolerances, smooth surface finishes, or consistency are crucial.

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Hot Rolled Steel

Hot Rolling is a mill process that almost all steel stock goes through. First, the steel is heated to over 1700 F (926 C), which is above the recrystallization temperature of the metal. Because of this, the steel is easy to manipulate, shape, and form. Once the material is shaped, it is left to cool to room temperature. During this process, the metal shrinks as it cools, which can cause some slight warpage. This is why the tolerance for hot roll steel is looser than cold rolled steel.

Hot rolled steel also tends to be cheaper than cold rolled steel because of the reduced tolerances and slightly lower strength.

You can visually identify hot rolled steel by the following traits:

  • A rough and scaly surface
  • A dry or oil-free finish
  • Any edges on the material are rounded

Use hot rolled steel for projects where low cost, high strength, or high quantity are needed. Construction, welding, railroads, and I-beams all typically use hot roll. If you need precise shapes or tight tolerances, use cold rolled steel.

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Cold Rolled Steel

Cold roll is initially hot roll material. But then once it has cooled, it undergoes further processing. While at room temperature, cold rolled steel is either annealed or drawn through rollers, depending on what the manufacturer needs the metal to do. These processes tighten the material tolerance and actually make the material stronger. The surface finish, tolerance, straightness, and consistency of cold rolled steel will always be superior to hot rolled steel. As such, it is usually a bit more expensive.

If the cold rolled product was annealed, it will be easier to work than hot rolled material. It should also be heat treated to harden it further once you’ve worked it into the shape you want. If it has just gone through rollers, then it will be stiffer and harder to machine.

You can visually identify cold rolled steel by the following traits:

  • A smooth surface
  • An oily or greasy finish
  • Any edges are sharp

Cold rolled steel is used when tolerance, higher strength, or surface finish are the most important qualities.

Cold Rolled, Cold Finished, or Cold Drawn?

It is worth noting that technically the term Cold Rolled/Cold Roll only refers to sheet or coil products. However, the term is so commonly used for any sort of steel product that receives further processing that is has become standard to use it for those products.

You might hear bar products referred to as Cold Finished or Cold Drawn, which typically involves four specific steps:

  • Cold drawing – Pulling the bar through rollers, this increases the strength, narrows the tolerance, and removes the need for further thermal treatments.
  • Turning – This process removes surface imperfections and further tightens the tolerance.
  • Grinding – This narrows the tolerances even further.
  • Polishing – The final step, this dramatically improves surface finish

You will also see this process written as Cold Rolled TGP or just TGP.

Shop the Products

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Carbon Steel Angle A36

A36 steel is an extremely common structural hot roll steel that offers strength and machinability at a cheap price point.

Shop A36 Angle Equal
Carbon steel Square bar

Carbon Steel Rectangle Bar 1018

7075 plate is known mostly for its use in aerospace applications with its great strength properties at a comparably light weight.

Shop 1018 Square Bar

About Online Metals

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Online Metals is the world’s leading eCommerce metal supplier, specializing in small quantity cut-to-size metals and plastics, delivered in a fast and reliable manner.

Since 1998, Online Metals has expanded our catalog to over 85,000 different cut sizes, grown our national footprint to seven pickup locations across the U.S., and continued to improve upon our best-in-class customer experience.

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