Cold drawn seamless tubing vs hot rolled seamless tubing

Cold drawn seamless tubing is a kind of steel pipe processed by a series of cold-drawing, cold-bending and other technologies under normal temperature environment; and hot rolled seamless tubing compared with cold drawn seamless tubing, it is in a steel pipe processed above the recrystallization temperature.

From the appearance, the common cold rolled seamless tubings are thin-walled small tubes, with glossy surface and high dimensional accuracy. Hot rolling is more of a thick-walled large tube with an oxide layer on the surface, black, or with red rust, and it is easily corroded.

From the point of view of the process flow,hot rolled seamless tubing (extruded seamless steel pipe) production process: tube blank→heating→piercing→three-roll skew rolling, continuous rolling→tube removal→sizing→cooling→straightening→hydraulic test→marking→warehousing;

The production process of cold drawn seamless tubing: tube blank → heating → perforation → heading → annealing → pickling → oiling → multi-pass cold drawing → billet tube → heat treatment → straightening → hydraulic test → marking → storage. The rolling method of cold drawn seamless tubing is more complicated than that of hot rolling, and the first three steps of their production process are basically the same.

From the perspective of the degree of bending of the section, when making a cold drawn seamless tubing, its section can have a certain degree of bending, and the bending is conducive to the bearing capacity of the cold drawn seamless tubing. However, when making a hot rolled seamless tubing, its section must not be partially bent, which will affect its service life.

From the perspective of surface accuracy, due to the difference in the production process of cold drawn seamless tubing and hot rolled seamless tubing, the surface finish of their dimensional accuracy accuracy is also different. Generally speaking, cold drawn seamless tubing are more precise than hot  rolled seamless tubing, and the surface finish is much better.

From the point of view of production tools, the production process of cold drawn seamless tubing and hot rolled seamless tubing is different. When the cold drawn seamless tubing is formed, it needs to go through the pipe slug process, heat treatment, perforation technology, hot rolling process, head treatment, pickling process, phosphating treatment, cold drawing process, annealing treatment, straightening treatment, pipe cutting process, As well as inspection of finished products, packaging and processing. The hot rolled seamless tubing needs to be subjected to the tube process, heat treatment, piercing and forming, tube rolling treatment, sizing treatment, cooling bed treatment, straightening treatment, switching treatment, and final inspection and packaging. From these introductions, it can be seen that there are certain differences in their technological procedures.

From the perspective of cross-sectional distribution, the cross-sectional distribution of cold drawn seamless tubing and hot rolled seamless tubing is also somewhat different, because the reasons for residual stress are different during forming. This leads to some bending of the residual stress of the cross-section of the cold drawn seamless tubing, while the residual stress of the hot rolled seamless tubing belongs to the film type.

In terms of categories, because the production processes of hot rolled seamless tubing and cold drawn seamless tubing are different, hot rolled seamless tubing sold on the market are divided into hot rolled seamless tubing and hot-rolled welded steel pipes; and cold drawn seamless tubing can be divided into cold drawn seamless tubing and cold-drawn welded steel pipe, cold drawn seamless tubing can be divided into two types: round pipe and special-shaped pipe.

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