The Advantages and Disadvantages of Hot Rolling and Cold Rolling

The advantage of hot rolling is that it can eliminate certain defects in the cast metal, such as welding pores, refining coarse grains and changing the distribution of inclusions, so that the compactness and mechanical properties of the metal are improved. Secondly, the raw material (steel ingot or billet) is increased in thermoplasticity, and the deformation resistance is lowered. Therefore, the amount of deformation can be increased during rolling, which is advantageous for improving productivity. In addition, due to the reduced metal deformation resistance, the requirements for the rolling equipment can be correspondingly lower, so that the cost of the equipment can be reduced and the energy consumption of the motor can be greatly reduced.

The disadvantage of hot rolling is that rolling with high temperature produces iron oxide scale so that the surface of the metal is not smooth; the size of the product is not accurate; the mechanical properties are not as good as cold rolling.

Compared with hot rolling, cold rolling has the advantages of good surface quality, accurate size, uniform thickness, good mechanical properties, and the ability to produce thin and small rolled piece. The disadvantage of cold rolling is that the rolling pressure is large, requiring high strength and precision of the equipment, large motor power, and high energy consumption. Therefore, the production of the generally cold rolled material is first performed by hot rolling and then cold rolling.