Cold rolled seamless steel tubes are cold-drawn or cold-rolled precision seamless steel tubes used for mechanical structures and hydraulic equipment with high dimensional accuracy and good surface finish. Cold rolled seamless steel tubes are divided into general steel pipes, low and medium pressure boiler steel pipes, high pressure boiler steel pipes, alloy steel pipes, stainless steel pipes, petroleum cracking pipes, and other steel pipes, as well as carbon thin-wall steel pipes, alloy thin-wall steel pipes, Stainless thin-walled steel pipes, special-shaped steel pipes. The outer diameter of hot rolled seamless steel tube is generally greater than 32mm and the wall thickness is 2.5-75mm. The diameter of cold rolled seamless pipe can be up to 6mm and the wall thickness can be up to 0.25mm. The outer diameter of thin-walled pipe can be up to 5mm and the wall thickness is less than 0.25mm. Cold rolling has higher dimensional accuracy than hot rolling.
1) Difference in process
1. Cold rolled formed steel allows local buckling of the section, so that the bearing capacity of the bar after buckling can be fully utilized; while hot-rolled steel does not allow local buckling of the section.
2. Hot rolled steel and cold-rolled steel have different causes of residual stress, so the distribution on the cross section is also very different. The residual stress distribution on the section of cold-formed thin-walled steel is curved, while the distribution of residual stress on the section of hot-rolled or welded steel is thin-film.
3. The free torsional stiffness of hot rolled steel is higher than that of cold rolled steel, so the torsion resistance of hot rolled steel is better than that of cold rolled steel.
2) Different advantages and disadvantages
Advantages: fast forming speed, high output, and does not damage the coating, can be made into a variety of cross-sectional forms to meet the needs of the use conditions; cold rolling can cause large plastic deformation of the steel, thereby improving the yield of the steel point.
Disadvantages:
1. Although there is no thermal plastic compression during the forming process, residual stress still exists in the section, which will inevitably affect the overall and local buckling characteristics of the steel;
2. The cold rolled section steel style is generally an open section, which makes the free torsional stiffness of the section lower. It is prone to torsion when under bending, and it is prone to bending and torsion buckling under pressure, and its torsion resistance is poor;
3. The wall thickness of cold rolled steel is small, and there is no thickening at the corners where the plates are joined, and the ability to withstand local concentrated loads is weak.
1) Difference in process
1. Cold rolled formed steel allows local buckling of the section, so that the bearing capacity of the bar after buckling can be fully utilized; while hot-rolled steel does not allow local buckling of the section.
2. Hot rolled steel and cold-rolled steel have different causes of residual stress, so the distribution on the cross section is also very different. The residual stress distribution on the section of cold-formed thin-walled steel is curved, while the distribution of residual stress on the section of hot-rolled or welded steel is thin-film.
3. The free torsional stiffness of hot rolled steel is higher than that of cold rolled steel, so the torsion resistance of hot rolled steel is better than that of cold rolled steel.
2) Different advantages and disadvantages
Advantages: fast forming speed, high output, and does not damage the coating, can be made into a variety of cross-sectional forms to meet the needs of the use conditions; cold rolling can cause large plastic deformation of the steel, thereby improving the yield of the steel point.
Disadvantages:
1. Although there is no thermal plastic compression during the forming process, residual stress still exists in the section, which will inevitably affect the overall and local buckling characteristics of the steel;
2. The cold rolled section steel style is generally an open section, which makes the free torsional stiffness of the section lower. It is prone to torsion when under bending, and it is prone to bending and torsion buckling under pressure, and its torsion resistance is poor;
3. The wall thickness of cold rolled steel is small, and there is no thickening at the corners where the plates are joined, and the ability to withstand local concentrated loads is weak.
