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Cold-rolled coil and hot-rolled coil are both flat metal materials needed for economic construction, and can be used in the manufacture of furniture, automobiles, ships, building materials and other mass production fields. Although they are all coil materials, there are differences in many aspects such as production process, physical and chemical properties. The following Shanghai hot rolled coil manufacturers from five aspects to explain the difference between them.
First, the production process is different
Hot rolled coil refers to the heating of raw materials to a certain temperature through preheating furnace, and then rough rolling, and in the subsequent rolling mill after many rolling cooling, and finally form a flat metal material.
Cold-rolled coils need to first heat the billet to a certain temperature, and then through continuous rolling or repeated rolling into a thinner steel plate. It then goes into a cold mill and is rolled again into a finer steel sheet.
Second, different temperature states
The temperature required for hot-rolled coil production is higher, up to more than 1000 degrees Celsius, while cold-rolled coil requires a low temperature state for processing.
Therefore, because the process of hot rolling needs to be carried out under high temperature conditions, it is easy to lead to changes in the structure of the chemical elements in the steel, and problems such as steel deformation and cracks often occur. In the process of cold rolling, the temperature is lower and the chemical reaction is less obvious, so the coil produced is less prone to these problems.
Three, the accuracy is different
The hot rolled coil produced by multi-pass rolling needs to withstand relatively high temperature in the manufacturing process, which leads to certain protrusions and bubbling on its surface, and thus the surface is not smooth enough.
The cold-rolled coil, due to the relatively low temperature in the production process, produces a smooth surface, relatively uniform thickness, and higher precision.
Fourth, there are differences in mechanical properties
Hot-rolled coil has a significant effect on the yield and strength of steel, giving it a more uniform strength and a more conventional metallographic structure than cold-rolled coil. Cold-rolled steel plates have better mechanical properties, uniform color coating, polished surface and uniform thickness. They can be adapted to a variety of deep drawing, shearing, extrusion and bending processes, which can improve their physical and chemical properties.
Five, the difference in heat resistance
Hot-rolled coils are thicker, their packing density is greater than that of cold-rolled coils, and can be used at higher temperatures. Cold rolled coil due to the relatively thin thickness, and the development of a wide variety of cold rolled coil suitable for specific engineering applications, can meet the requirements of higher performance, such as strength low alloy steel coil, so it can be more widely used.
To sum up, there are differences between cold-rolled coil and hot-rolled coil in terms of production process, physical and chemical properties, mechanical properties and heat resistance. Therefore, the use of the occasion is also different. Choose the right cold-rolled coil or hot-rolled coil according to different use occasions, specific requirements and materials, argonauts, pressure vessels and other requirements.
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