The general seamless steel pipe production process can be divided into cold drawing and hot rolling two, cold rolled seamless steel pipe production process is generally more complex than hot rolling, the pipe blank first to carry out three-roll continuous rolling, after extrusion to carry out sizing test, if the surface does not respond to cracks after the round pipe to be cut by the cutting machine, cut the length of about one meter of billet. Then enter the annealing process, annealing to use acid liquid for pickling, pickling should pay attention to whether there is a large amount of blistering on the surface, if there is a large number of blistering production, the quality of the steel pipe does not meet the standard of response. In appearance, cold-rolled seamless steel pipe is shorter than hot-rolled seamless steel pipe, and 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 steel pipe, the surface does not have too much roughness, and the caliber does not have too many burrs. The delivery status of hot-rolled seamless steel pipe is generally delivered after heat treatment in the hot-rolled state. The hot-rolled seamless steel pipe should be strictly hand-selected by the staff after the quality inspection, and the surface should be oiled after the quality inspection, followed by multiple cold drawing experiments, and the perforation experiment should be carried out after the hot rolling treatment, and if the perforation expansion is too large, it will be straightened and corrected. After straightening, it is transferred by the conveyor to the flaw detector for flaw detection experiments, and finally labeled and arranged specifications and placed in the warehouse.

Hot rolling

Round billet → heating →perforation→ three-roll oblique rolling, continuous rolling or extrusion→→ de-sizing (or reducing diameter), → cooling→ straightening→ hydrostatic test (or flaw detection) → marking → warehousing Seamless steel pipe is made of steel ingots or solid pipe billets made of capillaries through perforation, and then made by hot rolling, cold rolling or cold drawing. The specifications of seamless steel pipes are expressed in the number of millimeters of outer diameter * wall thickness. Seamless steel pipes are divided into two categories: hot-rolled and cold-rolled (dialed) seamless steel pipes. Hot rolled seamless steel pipes are divided into general steel pipes, low and medium pressure boiler steel pipes, high pressure boiler steel pipes, alloy steel pipes, stainless steel pipes, petroleum cracking pipes, geological steel pipes and other steel pipes. In addition to general steel pipes, low and medium pressure boiler steel pipes, high pressure boiler steel pipes, alloy steel pipes, stainless steel pipes, petroleum cracking pipes, and other steel pipes, cold-rolled (dialed) seamless steel pipes also include carbon thin-walled steel pipes, alloy thin-walled steel pipes, stainless thin-walled steel pipes, and special-shaped steel pipes. The outer diameter of hot-rolled seamless pipe is generally greater than 32mm, the wall thickness is 2.5-200mm, the diameter of cold-rolled seamless steel pipe can be up to 6mm, the wall thickness can be 0.25mm, the outer diameter of thin-walled pipe can be up to 5mm, the wall thickness is less than 0.25mm, and the dimensional accuracy of cold rolling is higher than that of hot rolling.

Generally, seamless steel pipe is made of 10, 20, 30, 35, 45 and other high-quality carbon steel 16Mn, 5MnV and other low-alloy structural steel or 40Cr, 30CrMnSi, 45Mn2, 40MnB and other bonded steel hot rolled or cold rolled. Seamless pipes made of 10, 20 and other low carbon steel are mainly used for fluid transportation pipelines. Seamless pipes made of medium carbon steel such as 45 and 40Cr are used to manufacture mechanical parts, such as stressed parts of automobiles and tractors. Generally, seamless steel pipes should be used to ensure strength and flattening test. Hot rolled steel pipes are delivered in hot rolled state or heat treated state; Cold rolled is delivered in hot and heat-treated state.

Hot rolling, as the name implies, the temperature of the rolled parts is high, so the deformation resistance is small, and a large amount of deformation can be achieved. Taking the rolling of steel plate as an example, the thickness of the continuous casting billet is generally about 230mm, and after rough rolling and finishing rolling, the final thickness is 1~20mm. At the same time, due to the small width-to-thickness ratio of the steel plate, the dimensional accuracy requirements are relatively low, and the plate shape problem is not easy to occur, and the convexity is mainly controlled. For the organization requirements, it is generally achieved by controlled rolling and cold control, that is, controlling the opening temperature and final rolling temperature of finishing rolling. Round pipe billet → heating→ perforation→ heading→ annealing→ pickling→ oiling (copper plating), →multi-pass cold drawing (cold rolling) → billet pipe→ heat treatment→ straightening→ hydrostatic test (flaw detection) → marking → storage

Process

Pipe blank – inspection – peeling – inspection – heating – perforation – pickling – grinding – lubrication air drying – welding head – cold drawing – solution treatment – pickling – pickling passivation – inspection – cold rolling – degreasing – cutting head – air drying – internal polishing – outer polishing – inspection – marking – finished product packaging

Industrial tube process

Pipe blank – inspection – peeling – inspection – heating – perforation – pickling – mushroom repair – lubrication air drying – welding head – cold drawing – solution treatment – pickling – pickling passivation – inspection – constant temperature storage – delivery