A comparison of the production processes of HR coils and CRCA coils

by Ankur Js professional WRITTER

Let us start by understanding what rolling is. The process of rolling involves passing metal sheets through rollers for a uniformed and reduced thickness. Rolling can be done at room temperature or at an increased temperature.

When steel is passed through a roller to turn into a coil at a very high temperature (anything above room temperature) it is called “hot rolled” coil or HR Coil.  The process of hot rolling is when the metal is passed through rollers above the metal’s recrystallization temperature. This makes Hot rolled steel more malleable as compared to cold rolled steel. Apart from malleability there are other differences as well.

On the other hand, CRCA coils are a product of cold rolling close annealing. Cold Rolling is when the rolling process takes place at room temperature, the material is said to roll below its recrystallization temperature.  After undergoing the process of cold rolling, the coils become very hard lose ductility. In order to restore ductility these cold rolled coils are annealed in to proactive nitrogen-hydrogen atmosphere to obtain the desired orientation grain size.

Comparing Hot Rolled Steel and Cold Rolled Steel

Price: Hot rolled steel is less expensive than cold rolled steel. This is due to slightly stronger properties of cold rolled steel.  This makes it more attractive to use for metalworking companies.

 

Flexibility: Hot rolled steel is more malleable than cold-rolled steel. Since the process of Hot rolled steel requires heating steel above its recrystallization temperature or at it, it is easier to change the shape of hot-rolled steel. Whereas, during cold rolling, the steel is compressed under rollers at room temperature it becomes more difficult to deform.

 

Wide use in less time: Due to the flexibility of hot rolled metal, it becomes commonly usable as sheet metal, HR coils. Projects that involve hot rolled steel take much lesser time as compared to those with cold rolled steel.

 

Durability: Hot rolled steel is 20% weaker than cold rolled steel. The heat applied weakens the metal. Cold-rolled steel is significantly stronger as the rollers compress the steel at room temperature making it stronger due to strain hardening.

 

Surface Finish: Hot rolled steel is rougher to the touch as compared to cold rolled steel.  The colling process involved in Hot Rolled Steel causes elements to settle in rougher places, whereas, cold rolled steel is aesthetical smoother with lesser imperfections on the surface. Due to this surface finish, it is more suitable for certain projects like bridge constructions etc.

 

Tighter Tolerances: In the metalworking industry tolerance means thickness of the metal. The kind of tolerance offered by CRCA coils won’t be found in HR Coils. Cold-rolled steel is quite thin as compared to hot rolled steel but not at the cost of the strength. 

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Created on Mar 30th 2021 23:16. Viewed 278 times.

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