What are the disadvantages of hot and cold rolling processes for seamless tubes

　　Hot rolled and cold rolled (dial) seamless tubes

　　1. The cross-section of the cold-rolled seamless pipe is partially embossed, and then the bearing capacity of the bar can be fully utilized; and the hot-rolled steel does not agree with the section of the section.

　　2. The causes of residual stress in hot-rolled seamless square tubes and cold-rolled sections are different, so the dispersion on the sections is also very different. The residual stress distribution on the section of the cold-formed thin-walled steel is a tortuous type, and the residual stress distribution on the section of the hot-drawn steel or welded steel is a film type.

　　3. The freely changing stiffness of hot-rolled steel is higher than that of cold-rolled steel, so the torsional function of hot-rolled steel is better than that of cold-rolled steel. Cold-rolled seamless pipe cold-rolled seamless steel pipe refers to steel that is processed into various types by cold drawing, cold bending, cold drawing and other cold working at normal temperature.

　　Strengths: fast forming speed, high output value, and no damage to the coating, can be made into a variety of cross-sections to meet the needs of the conditions; cold rolling can cause large plastic deformation of the steel, and then improve the yield of the steel point.

　　Defect:

　　1. Although there is no hot plastic shrinkage during the forming process, there is still residual stress in the cross section, which inevitably affects the characteristics of the whole steel and part of the steel;

　　2. The cold-rolled steel profile is generally an open section, so that the freeness of the section changes less. It is simple to change when it is bent. It is simple to show bending and torsion when pressed, and the torsion resistance is poor.

　　3. The wall thickness of cold-rolled steel is small, and there is no thickening at the corner of the joint of the plate. The ability to gather loads is weak.

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