Production technology of hot rolled seamless steel pipe

Seamless steel pipe plays an important role in urban infrastructure and the production, processing and manufacturing of mechanical products. Therefore, driven by the market, its production and processing technology has developed rapidly. The production process of hot rolled seamless steel pipe is the production process of rolling above the metal recrystallization temperature. It is widely used because of its low energy consumption and good mechanical properties.

The production process of hot rolled seamless steel pipe mainly includes round billet, heating, perforation, three roll cross rolling, continuous rolling or extrusion, pipe stripping, sizing (or reducing), cooling, straightening, hydrostatic test, etc. Generally, perforation, pipe rolling and sizing reduction are the main deformation processes in the production process. The equipment used are piercing mill, pipe mill and sizing (reducing) mill. For each main deformation process, there are corresponding strict production process control requirements.

1. Perforation

In the process of perforation, the thickness of capillary wall is uniform, the ovality is small and the geometric size is small; The inner and outer surfaces of the capillary tube shall be relatively smooth without defects such as scabs, folds and cracks, so as to improve the mechanical properties; The piercing speed shall be consistent with the rolling cycle. During the pipe rolling process, the temperature of the steel pipe shall be kept above the metal recrystallization temperature, which meets the rolling needs.

2. Pipe rolling

In the process of pipe rolling, the steel pipe needs to have high wall thickness uniformity, so that the wall thickness of the steel pipe is relatively consistent; It is required to have good internal and external surface quality, avoid mechanical property defects such as mechanical wear, scratch and torsional stress crack on the internal and external surfaces during pipe rolling, and do not damage its internal stress structure and improve the mechanical property quality of the steel pipe.

3. Diameter reduction

The essence of the reduction process is to reduce the big circle to a small circle, and the total reduction rate and small single frame reduction rate required in the production process are used to determine the diameter; Try to realize diversified production of pipe blank, that is, one pipe blank can produce finished products with multiple pipe diameters; Try not to damage the smooth internal and external surfaces of the steel pipe, prevent mechanical damage to the internal stress of the steel pipe and improve its mechanical performance quality.