What are the Advantages and Disadvantages of Hot Rolling and Cold Rolling?

2023-04-11 Yan yifan China Sheet Metal Manufacturer, Custom made metal boxes, Industrial Machine Enclosures, Metal Enclosure, Metal Enclosures for Electronics, outdoor vending machine enclosures, sheet metal box manufacturers, sheet metal supplier, steel box manufacturers

Hot rolling: ingots or billets at room temperature is difficult to deform, not easy to process, generally heated to 1100 ~ 1250 ℃ for rolling, this rolling process is called hot rolling. The termination temperature of hot rolling is generally 800 to 900 ℃, after which it is generally cooled in air, and thus the hot rolling state is equivalent to normalizing treatment.

Advantages: fast forming, high yield, and do not damage the coating, can be made into a variety of cross-sectional forms to meet the needs of the conditions of use; cold rolling can make a large plastic deformation of steel, thereby increasing the yield point of steel.

Disadvantages: residual stresses still exist in the cross-section, which must have an impact on the overall and local buckling characteristics of the steel; the free torsional stiffness of the cross-section is low;

Cold rolling: refers to cold rolling with hot rolled steel coil as raw material at room temperature, after pickling to remove oxidation skin for pressure processing, the finished product is rolled hard coil. Although the process also heats up the steel sheet, it is still called cold rolling. General cold-rolled steel such as galvanized, color steel sheet must be annealed, so plasticity and elongation is also better, widely used in automotive, home appliances, hardware and other industries.

Advantages: It can destroy the casting organization of the ingot, refine the grain of steel, and eliminate the defects of microstructure, so that the steel organization is dense and the mechanical properties are improved. This improvement is mainly reflected along the rolling direction, so that the steel is no longer isotropic to a certain extent; bubbles, cracks and looseness formed during casting can also be welded together under the action of high temperature and pressure.

Disadvantages: After hot rolling, non-metallic inclusions inside the steel (pressed into thin sheets, the phenomenon of delamination; uneven cooling caused by residual stress, residual stress, although self-phase equilibrium, but the performance of steel members under the action of external forces still have some impact. Such as deformation, stability, fatigue resistance and other aspects may have a negative effect.

To sum up: The main difference between cold rolling and hot rolling is the temperature of the rolling process. “Cold” for room temperature, “hot” for high temperature.

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