The general production process of seamless steel tubes can be divided into two types: cold drawing and hot rolling. The production process of cold rolling seamless steel tubes is generally more complicated than that of hot rolling. In the sizing test, if the surface does not respond to cracks, the round tube will be cut by a cutting machine and cut into a billet with a length of about one meter. Then enter the annealing process, annealing should be pickled with an acidic liquid, and pay attention to whether there is a lot of blistering on the surface during pickling. If there is a lot of blistering, it means that the quality of the steel pipe does not meet the corresponding standard. In appearance, the cold-rolled seamless steel tube is shorter than the hot-rolled seamless steel tube. The wall thickness of the cold-rolled seamless steel tube is generally smaller than that of the hot-rolled seamless steel tube, but the surface looks brighter than the thick-walled seamless steel tube, and the surface is not too much. Much rough, and the caliber doesn't have too many burrs.
The delivery state of hot-rolled seamless steel tube is generally that the hot-rolled state is delivered after heat treatment. The hot-rolled seamless steel tube must be hand-selected strictly by the staff after the quality inspection. After the quality inspection, the surface should be oiled, followed by several cold-drawing experiments. After the hot-rolling treatment, the perforation experiment should be carried out. If the diameter of the perforation is too large, it should be straightened and corrected. After straightening, it will be sent to the flaw detector by the conveyor for the flaw detection experiment, finally labeled and arranged in specifications, and then placed in the warehouse.
Round tube blank→heating→piercing→three-roll skew rolling, continuous rolling or extrusion→tube removal→sizing (or reducing)→cooling→straightening→hydraulic test (or flaw detection)→marking→storage seamless steel tube It is made of steel ingots or solid tube blanks through perforation to make capillaries, and then hot-rolled, cold-rolled or cold-drawn. The specification of seamless steel tube is expressed by outer diameter * wall thickness mm.
The outer diameter of the hot-rolled seamless steel tube is generally greater than 32mm, and the wall thickness is 2.5-200mm. The outer diameter of the cold-rolled seamless steel tube can reach 6mm, and the wall thickness can reach 0.25mm. Rolling has higher dimensional accuracy than hot rolling.
Generally, seamless steel tubes are made of 10, 20, 30, 35, 45, and other high-quality carbon-bonded steels such as 16Mn, 5MnV, and other low-alloy structural steels or 40Cr, 30CrMnSi, 45Mn2, 40MnB, and other combined steels by hot rolling or cold rolling. Seamless pipes made of low carbon steel such as 10 and 20 are mainly used for fluid transportation pipelines. 45, 40Cr, and other medium carbon steel seamless pipes are used to manufacture mechanical parts, such as the stressed parts of automobiles and tractors. Generally, a seamless steel tube is used to ensure strength and flattening test. Hot-rolled steel pipes are delivered in a hot-rolled or heat-treated state; cold-rolled steel pipes are delivered in a heat-treated state.
Hot rolling, as the name implies, 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 steel plates as an example, the thickness of the continuous casting slab 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 main control is to control the crown. For those with organizational requirements, it is generally realized by controlled rolling and controlled cooling, that is, controlling the opening temperature and final rolling temperature of finishing rolling. Round tube billet → heating → perforation → heading → annealing → pickling → oiling (copper plating) → Multi-pass cold drawing (cold rolling) → billet tube → heat treatment → straightening → hydraulic test (flaw detection) → marking → storage.
The above is about the production process of seamless steel tubes, I hope it will be helpful to everyone. If you are interested in seamless steel tubes, welcome to pay attention to our website.
