Production Processes of Seamless Steel Tube

Seamless steel tube is a kind of long steel with a hollow round section, seamless steel pipe is widely used in many industries. Today let us learn about the main production process about the steel  steel tube.

1 hot-rolled production process ( main inspection process):

Tube blank preparation and inspection →tube billet heating→perforation→rolling tube→seamless steel pipe reheating→fixing (reducing) diameter→heat treatment →finishing of finished pipe→finishing→inspection (non-destructive, physicochemical, table inspection)→warehouse

2 cold rolling (drawing) seamless steel pipe production process: Blank preparation → pickling lubrication → cold rolling (pull) → heat treatment → straightening → finishing → inspection.

Generally, the production process of 10# seamless pipe manufacturers can be divided into cold drawing and hot rolling. The production process of cold rolled seamless steel tube is generally more complicated than hot rolling. The pipe blanks must first be rolled in three rolls, after extrusion. To perform the sizing test, if the surface does not respond to the crack, the seamless steel tube is cut by a cutter and cut into a blank of about one meter in length. Then enter the annealing process, the acidification should be acid-washed with acid liquid. When pickling, pay attention to whether there is a large amount of foaming on the surface. If there is a large amount of foaming, the quality of the seamless tube will not reach the corresponding standard. The appearance of cold-rolled seamless steel pipe is shorter than that of hot-rolled seamless carbon steel pipe. The wall thickness of cold-rolled seamless steel pipe is generally smaller than that of hot-rolled seamless steel pipe, but the surface looks brighter than thick-walled seamless carbon steel tubing, and the surface is not too. It’s rough and there aren’t too many burrs in the caliber.

The outer diameter of hot-rolled seamless pipe is generally larger than 32mm, the wall thickness is 2.5-200mm, the outer diameter of cold-rolled seamless steel tube can reach 6mm, the wall thickness can be 0.25mm, the outer diameter of thin-walled pipe can reach 5mm, the wall thickness is less than 0.25mm, cold rolling is more accurate than hot rolling.

Generally, the seamless steel tube is formed by hot-rolled or cold-rolled low-alloy structural steels such as 10, 20, 30, 35, 45, etc., such as 16Mn and 5MnV, or 40Cr, 30CrMnSi, 45Mn2, 40MnB, and the like. Seamless pipes made of low carbon steel such as 10 and 20 are mainly used for fluid conveying pipes. 45, 40Cr and other medium carbon steel seamless pipes are used to make mechanical parts, such as the force parts of automobiles and tractors. Generally, seamless carbon steel pipe are required to ensure strength and flattening test. The seamless steel tube is delivered at hot rolled state or heat treated state; the cold rolling is delivered in a heat treated state.

Hot rolling, as the name suggests, has a high temperature of the rolled piece, so the deformation resistance is small and a large amount of deformation can be achieved. Taking the rolling of the steel sheet as an example, the thickness of the continuous casting blank is about 230 mm, and after rough rolling and finish rolling, the final thickness is 1 to 20 mm. At the same time, due to the small width-to-thickness ratio of the steel plate, the dimensional accuracy requirement is relatively low, and the shape problem is not easy to occur, and the convexity is mainly controlled.