The production process of steel pipes is divided into cold rolling and hot rolling. The quality, performance and function of the steel pipes produced by these two processes are different.
Cold-rolled steel pipes allow local buckling in the cross-section, so that the bearing capacity of the rods after buckling can be fully utilized; while hot-rolled steel pipes do not allow local buckling in the cross-section.
The outer diameter of hot-rolled steel pipes is generally greater than 32mm, and the wall thickness is 2.5-75mm. The diameter of cold-rolled seamless steel pipes can be up to 6mm, and the wall thickness can be up to 0.25mm. The outer diameter of thin-walled pipes can be up to 5mm, and the wall thickness is less than 0.25mm. The cold-rolled ratio Hot rolling has high dimensional accuracy.
The causes of residual stress in hot-rolled steel pipes and cold-rolled steel pipes are different, so the distribution on the cross-section is also very different. The residual stress distribution on the cold-formed thin-walled steel section is curved, while the residual stress distribution on the hot-rolled steel pipe or welded steel section is film-type.
The free torsional stiffness of hot-rolled steel pipes is higher than that of cold-rolled steel pipes, so the torsional performance of hot-rolled steel pipes is better than that of cold-rolled steel pipes.
