In the steel rolling production line, both hot rolling and cold rolling are processes for processing steel plates, which have a great impact on the structure and properties of steel. Some users want to know the difference between hot rolling and cold rolling? Today, the editor of Judian will introduce it to you.
The first is the difference between processing raw materials. Hot rolling mainly uses continuous casting slabs or blooming slabs as raw materials, and cold rolling mainly uses hot rolled steel coils as raw materials.
Then there is the difference in craftsmanship.
Hot rolling is the hot-rolled strip from the rolling mill after being heated, cooled to the set temperature by laminar flow, from the coiler to the strip roll, cooled to the strip roll, and then finished into the final product through finish rolling.
The advantage of hot rolling is that it can destroy the casting structure of the ingot, refine the grain of the steel, and eliminate the defects of the microstructure, so that the steel structure is dense and the mechanical properties are improved.
However, after the steel is hot rolled, the internal non-metallic inclusions are pressed into thin sheets, which will cause delamination. And it is possible that interlaminar tearing occurs when the weld shrinks, which has some impact on the properties of the steel.
Cold rolling is to carry out continuous cold rolling after pickling to remove oxide scale, and the final product is rolled hard coil. Due to continuous cold deformation, cold work hardening is caused, which increases the strength and hardness of the hard-rolled coil.
Cold rolling has fast forming speed, high output, and little damage to the coating. It can be made into a variety of cross-sections, so that the steel has a large plastic deformation to meet the needs of various conditions.
However, the cold-rolled steel has residual stress in the section, and the free torsional stiffness is low. It is prone to bending-torsional buckling under compression, has poor torsional performance, and has a small wall thickness. If there is no thickening at the corners where the plates join, the ability to bear local concentrated loads is weak.
This is what we share with you, about the process knowledge of hot rolling and cold rolling, I hope it can be helpful to you.
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