New knowledge of steel pipe: the difference between hot rolled seamless steel pipe and cold rolled seamless steel pipe

New steel pipe knowledge: the difference between hot-rolled seamless steel pipe and cold-rolled seamless steel pipe Hot-rolled and cold-rolled steel are all steel or steel forming processes, they have a great impact on the organization and performance of steel, steel rolling mainly Hot rolling is the main method, and cold rolling is only used for the production of small steels and sheets.
1. Hot rolling Advantages: It can destroy the ingot casting structure, 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. This improvement is mainly reflected in the rolling direction, so that the steel is no longer isotropic; to a certain extent, the bubbles, cracks and looseness formed during pouring can also be welded under high temperature and pressure.
Disadvantages: 1. After hot rolling, the non-metallic inclusions (mainly sulfides and oxides, and silicates) inside the steel are pressed into thin sheets and a layering (sandwich) phenomenon occurs. Stratification greatly degrades the properties of the steel in the thickness direction, and it is possible that interlayer tearing occurs when the weld seam shrinks. The local strain induced by weld shrinkage often reaches several times the strain at yield point, which is much larger than the strain caused by load; 2. Residual stress caused by uneven cooling. Residual stress is the stress of the internal self-phase equilibrium under the action of no external force. Hot rolled steel of various sections has such residual stress. The larger the section size of general steel, the greater the residual stress. Although the residual stress is self-balanced, it still has some influence on the performance of steel components under external forces. Such as deformation, stability, anti-fatigue and other aspects may have an adverse effect.
Sales of thick-walled seamless steel pipe, large-diameter seamless steel pipe, hot-spreading seamless steel pipe manufacturers - Shandong Liaogang Metal.
Cold Rolling refers to the processing of steel plates or strips into various types of steel at cold temperatures by cold drawing, cold bending, cold drawing, etc. at room temperature.
Advantages: high forming speed, high yield, and no damage to the coating, can be made into a variety of cross-sectional forms to meet the needs of the use of the conditions; cold rolling can make the steel produce a large plastic deformation, thereby increasing the yield of the steel point.
Disadvantages:1. Although there is no hot plastic compression in the forming process, there are still residual stresses in the section, which will inevitably affect the properties of the steel as a whole and local buckling; 2. Cold rolled section steel style is generally open section, making the section free Low torsional stiffness. It tends to twist during bending, bending and torsion buckling tends to occur during compression, and the torsion resistance is poor. 3. The wall thickness of cold-rolled formed steel is relatively small, and it is not thickened at the corners where the plates join, and it can withstand locality. The ability to concentrate loads is weak.
Sales of thick-walled seamless steel pipe, large-diameter seamless steel pipe, hot-spreading seamless steel pipe manufacturers - Shandong Liaogang Metal.
The main differences between hot and cold rolling are:
1. Cold-formed steels allow local buckling of the cross-section so that the post-buckling bearing capacity can be fully utilized; hot-rolled steels do not allow local buckling of the cross-section.
2. The causes of residual stress in hot-rolled steel and cold-rolled steel are different, so the distribution on the cross-section is also very different. The residual stress distribution on the cold-formed thin-wall section steel is curved, while the residual stress distribution on the hot-section or welded section is thin-film type.
3. The torsional stiffness of hot-rolled steel is higher than that of cold-rolled steel, so the torsional performance of hot-rolled steel is better than that of cold-rolled steel.

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