What Is The Difference Between Cold-drawn Steel Pipe And Hot-rolled Steel Pipe?

Hot rolling

to destroy the casting organization of the ingot, refine the grain of steel, and eliminate the defects of microstructure, thus making the steel organization dense, mechanical properties are improved. This improvement is mainly reflected in the direction along the rolling, so that the steel is no longer isotropic body to a certain extent; casting the formation of bubbles, cracks and sparsity, but also in the high temperature and pressure is welded together.

Cold Rolling

Cold rolling is the process of processing steel plates or strips into various types of steel at room temperature through cold drawing, cold bending, cold pulling and other cold processes.
Advantages: fast molding speed, high yield, and no damage to the coating, can be made into a variety of cross-sectional forms to adapt to the needs of the conditions of use; cold rolling can make the steel to produce a large plastic deformation, thereby increasing the yield point of steel.

Difference 1:

in the production of cold rolled pipe, its cross-section can have a certain degree of bending, bending is conducive to the cold rolled pipe capacity. However, in the production of hot-rolled tube, its cross-section is not allowed to have a localized bending phenomenon, which will affect its service life.

Difference 2:

due to the cold rolled pipe and hot rolled pipe production process is different, so their dimensional accuracy precision surface finish is not the same. Generally speaking, the cold rolled pipe is higher than the precision of the hot rolled pipe, the surface finish is also much better.

Difference 3:

cold rolled pipe and hot rolled pipe production process is different. Cold rolled pipe in the production of molding, need to go through the pipe grudge process, heating treatment, piercing technology, hot rolling process, beating treatment, pickling works, phosphating treatment, cold drawing process, annealing treatment, straightening treatment, cutting process, as well as inspection of the finished product, packing treatment. While the hot rolled pipes need to carry out the pipe grudge process, heating treatment, piercing and forming, rolling treatment, sizing treatment, cold bed treatment, straightening treatment, switching treatment, as well as the final inspection and packing treatment. From these introductions can be seen in their process procedures have certain differences.

Difference 4:

cold rolled tube and hot rolled tube cross-section distribution is also somewhat different, this is because in the production of molding, residual stresses arising from different reasons. This leads to the cold rolled tube cross-section of the residual stress has some bending, while the residual stress of the hot rolled tube is a thin film type.

Difference 5:

Because the production process of hot rolled pipe and cold rolled pipe is different, so the hot rolled pipe sold on the market is divided into hot rolled seamless steel pipe and hot rolled welded steel pipe; while the cold rolled pipe can be divided into cold rolled seamless steel pipe and cold rolled welded steel pipe, cold rolled seamless steel pipe can be divided into round and shaped tube of these two kinds of pipe.
Two kinds of steel pipe in the finished product is not much difference, are generally manufactured in accordance with the standard. Mechanical properties are not what kind of difference, the existence of most of the processing technology is different, as well as the final out of the precision is different, generally speaking, cold-drawn dimensional accuracy and surface finish is higher.