The difference between cold-rolled steel and hot-rolled steel is not in the smelting process, but in the rolling temperature, or the rolling termination temperature. If the final rolling temperature is lower than the recrystallization temperature of the steel, it becomes cold rolled steel.

Hot-rolled steel is easy to roll and has high rolling efficiency. However, the steel is oxidized under hot-rolling conditions and the surface of the product is dark gray and dull.

Cold-rolled steel requires high-power rolling mills and low rolling efficiency. In addition, intermediate annealing is required during the rolling process to eliminate work hardening, so the cost is also high.

However, cold-rolled steel has a bright surface and good quality and can be directly used to process finished products. Therefore, cold-rolled steel plates are widely used.

1. The essential differences

The essence of cold-rolled steel: Cold-rolled steel is steel produced by cold rolling. Cold rolling is to further thin the steel plate to a target thickness at room temperature.

The essence of hot-rolled steel: Hot-rolled steel is a kind of steel that is rolled above the recrystallization temperature.

2. The characteristics different

Characteristics of cold-rolled steel: The thickness of cold-rolled steel plate is more accurate, and the surface is smooth and beautiful. It also has various superior mechanical properties, especially in terms of processing performance.

Characteristics of hot-rolled steel: During hot-rolling, the metal has high plasticity and low deformation resistance, which greatly reduces the energy consumption of metal deformation. Hot rolling can improve the processing performance of metals and alloys, that is, break the coarse grains in the casting state, significantly heal cracks, reduce or eliminate casting defects, transform the as-cast structure into a deformed structure, and improve the processing performance of the alloy.

3. Different processing requirements

Processing requirements for cold-rolled steel: Cold-rolled steel requires high-power rolling mills and low rolling efficiency. In addition, intermediate annealing is required during the rolling process to eliminate work hardening, so the cost is also high.

Processing requirements for hot-rolled steel: Hot-rolled steel is easy to roll and has high rolling efficiency. The hot-rolling temperature includes the opening rolling temperature and the final rolling temperature. The determination of the opening rolling temperature is mainly based on the solidus line temperature in the alloy phase diagram. About 80%, and the final rolling temperature should be determined based on the plasticity diagram of the alloy, which is generally required to be controlled above the recrystallization temperature of the alloy.

4. The uses different 

(1) Uses of cold-rolled steel:

Cold-rolled plates and strips are widely used, such as automobile manufacturing, electrical products, rolling stock, aviation, precision instruments, food cans, etc. Cold-rolled thin steel plate is the abbreviation of ordinary carbon structural steel cold-rolled plate. It is also called cold-rolled plate, commonly known as cold plate, and is sometimes mistakenly written as cold-rolled plate. Cold plate is made of ordinary carbon structural steel hot-rolled steel strip, which is further cold-rolled into a steel plate with a thickness of less than 4mm.

Since rolling at room temperature does not produce iron oxide scale, the cold plate has good surface quality and high dimensional accuracy. Coupled with annealing treatment, its mechanical properties and process performance are better than hot-rolled thin steel plates. In many fields, especially In the field of home appliance manufacturing, it has gradually been used to replace hot-rolled thin steel plates.

(2) Uses of hot-rolled steel:

Structural steel: mainly used in the production of steel structural parts, bridges, ships, and vehicles.

Weathering-resistant steel: Adding special elements (P, Cu, C, etc.), it has good corrosion resistance and atmospheric corrosion resistance. It is used in the production of containers, special vehicles, and building structures.

Automotive structural steel: high-strength steel plate with good stamping performance and welding performance, used in the production of automotive FRAME, WHEEL, etc.

Hot-rolled special steel: carbon steel, alloy steel, tool steel for general mechanical structures, used in the production of various mechanical parts after heat treatment.

Cold-rolled original plate; used to produce various cold-rolled products, including CR, GI, color-coated plates, etc.

Steel plate for steel pipes: It has good processing performance and compressive strength, and is used to produce high-pressure gas pressure vessels with an internal volume of less than 500L filled with LPG, acetylene gas and various gases.

Steel plate for high-pressure vessels: It has good processing performance and compressive strength and is used to produce high-pressure gas pressure vessels with an internal volume of less than 500L filled with LPG, acetylene gas and various gases.

Stainless steel plate: Stainless steel has good corrosion resistance and is mainly used in the food industry, surgical equipment, aerospace, petroleum, chemical and other industries.