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Hot rolling and cold rolling are the two most commonly used profile or plate molding process, but also the most basic way of heat treatment of steel, through the heat treatment can have a great impact on the structure and performance of steel, steel rolling tension to hot rolling, cold rolling is only used for the production of small sizes of profiles and thin plates, the following is an introduction to what the difference between them.

First, hot rolling

Benefits: can destroy the casting structure of the ingot, refine the grain of steel, and eliminate the defects of the microstructure, so that the steel structure is dense, mechanical properties are improved. This improvement is strongly embodied in the bias along the rolling, so that the steel is no longer isotropic body to a certain extent; casting the formation of bubbles, cracks and loose, but also in the role of high temperature and pressure is welded together.

Disadvantages:1, after the end of hot rolling, steel internal non-metallic mixtures (nervous sulfides and oxides, and silicates) is pressed into thin sheets, the appearance of delamination (interlayer) signs. Delamination of the steel along the thickness of the tensile properties greatly deteriorated, and there is a risk of interlayer tearing in the weld tightening. Weld tightening induced local strain often reaches several times the yield point strain, much larger than the load-induced strain.

2, uneven cooling caused by dross stress. Dregs stress is in the absence of external forces within the self-equilibrium stress, all kinds of cross-section of hot-rolled steel have this kind of dregs stress, as a rule, the larger the cross-section size of the steel, dregs stress is also larger. Although the dregs stress is self-equilibrium, but the performance of steel components in the external force or have a certain impact. Such as deformation, solidity, resistance to commissioning, etc. are probably breeding unlucky effect.

Second, cold rolling

Refers to at room temperature, subverted cold drawing, cold bending, cold drawing and other cold processing of steel plate or steel strip processing into various types of steel.

Advantages: molding speed, high yield, and does not damage the coating, can be made into a variety of cross-section situation, in order to comply with the use of the necessary conditions; cold rolling can make the steel to produce a large plastic deformation, thereby increasing the yield point of steel.

Disadvantages: 1, although the molding process is not reversed hot plastic compression, but there is still dregs stress within the cross-section, the characteristics of the steel group and local buckling certainly have an impact.

2, cold rolled steel style as usual for the open section, making the section of the free rotation stiffness is low. In the bending is easy to rotate, pressure is easy to bend and twist flexure, torsion performance is poor.

3, cold rolled forming steel wall thickness is small, in the corner of the plate articulation and no thickening, subject to localized convergent load capacity is weak.