Cold rolling is done when the metal is able to form new grains as the old ones are deformed by rolling and bending the metal.
Cold rolled vs hot rolled sheet metal.
Hot rolled steel involves rolling the steel at high temperatures where cold rolled steel is processed further in cold reduction mills where the material is cooled followed by annealing and or tempers rolling.
The differences between hot rolled steel and cold rolled steel relates to the way these metals are processed at the mill and not the product specification or grade.
Hot rolled steel also tends to be cheaper than cold rolled steel because of the reduced tolerances and slightly lower strength.
It s through a series of breakdown semi finishing sizing semi roughing roughing and finishing that cold rolled steel shapes can be created.
During cold rolling the steel is annealed or exposed to heat and allowed to cool which improves ductility.
Hot rolling and cold rolling are two methods of shaping steel.
Cold rolled has a smooth and shiny finish while hot rolled has a grey and scaly finish.
During the hot rolling process steel is heated to its melting point while being worked changing the composition of the steel to make it more malleable.
Cold worked steels are typically harder and stronger than standard hot rolled steels.
Cold rolled steel is essentially hot rolled steel that has been through further processing.
The steel cools at room temperature.
Whereas cold rolled steel is processed in cold reduction mills followed by annealing and tempering.
Typically mills take hot rolled steel after it s mostly or completely cooled and work it to its final dimension by either rolling it extruding it or drawing the metal over a mandrel.
There are some fundamental differences between these two types of metal.
Basic difference between hot rolled and cold rolled steel is the way they are processed.
During this process the metal shrinks as it cools which can cause some slight warpage.
Cold rolled has sharper corners and more precise dimensions than hot rolled.
Hot rolled steel is rolled or shaped at a high temperature while cold rolled steel is rolled at room temperature.
Hot rolled steel involves rolling the steel above re crystallization temperatures.
But cold rolled steel undergoes additional processing steps resulting in improved properties that can be exploited for different applications.
Once hot rolled steel has cooled it is then re rolled at room temperature to achieve more exact dimensions and better surface qualities.
This is why the tolerance for hot roll steel is looser than cold rolled steel.
Both hot rolled steel and cold rolled steel start out in essentially the same way and both can have the same grades and specifications.
Each type of steel has its advantages and disadvantages and costs for the two types of steel are also different.
This keeps the market price of hot rolled steel lower.
Compared to hot rolled steel cold rolled steel has a nearly 20 increase in strength through the use of strain hardening.
