What is the Difference Between Hot Rolled and Cold Rolled Steel?

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The main difference between hot rolled and cold rolled steel lies in the temperature at which they are processed. Hot rolled steel is rolled at high temperatures (typically over 1700˚F), while cold rolled steel is processed in cold reduction mills at or near room temperature. Here are some key differences between the two:

Hot Rolled Steel

  • Rolled at high temperatures above the material's recrystallization temperature
  • Rough edges and surfaces that require further processing, like decarburization
  • Larger tolerances for dimensions due to non-uniform shrinkage during cooling
  • Cheaper than cold rolled steel
  • Suitable for welding, railroad tracks, and I-beams

Cold Rolled Steel

  • Processed at or near room temperature
  • Sharp edges and a very smooth surface texture
  • More precise dimensions and greater strength
  • More expensive than hot rolled steel
  • Suitable for applications that require a precise shape, such as car bodies or household appliances

In summary, hot rolled steel is cheaper and has larger tolerances, making it suitable for applications that require welding or rougher surfaces. Cold rolled steel, on the other hand, is more expensive and has more precise dimensions, making it suitable for applications that require a smooth finish and precise shape.

Comparative Table: Hot Rolled vs Cold Rolled Steel

The main differences between hot rolled and cold rolled steel are their processing temperatures, strength, finish, and workability. Here is a table summarizing these differences:

Property Hot Rolled Steel Cold Rolled Steel
Processing Temperature Above recrystallization temperature Below recrystallization temperature
Tensile Strength 67,000 PSI 85,000 PSI
Yield Strength 45,000 PSI 70,000 PSI
Modulus of Elasticity 29,000 KSI 27,557 - 30,458 KSI
Shear Modulus 11,500 KSI 11,600 KSI
Finish Rough, scaly surface, may require additional processing for desired finish Smooth, even surface, ready for use as-is or with minimal processing
Workability More malleable and ductile, suitable for various shapes Less formable and more difficult to manipulate

Hot rolled steel is processed at high temperatures, making it easier to shape and form, while cold rolled steel is processed at room temperature and is stronger and has a smoother finish. Hot rolled steel is more suitable for applications that require malleability and ductility, while cold rolled steel is better for precise shapes and tolerances.