Definition of of hot rolled smls steel tubes
Smls steel pipe is made of a whole round steel perforated. Steel pipes with no welds on the surface are called seamless steel pipes. According to the production method, smls steel pipes can be divided into hot rolled seamless steel pipes, cold rolled seamless steel pipes, cold drawn seamless steel pipes, extruded seamless steel pipes, jacked pipes, etc. Among them, the hot rolling process accounts for a large proportion in the production of seamless steel pipes and is a key step for the quality of seamless steel pipes. In the hot rolling process, the continuous casting billet is first unloaded into the hot rolling mill.
In the hot rolling process, the continuous cast billet is first unloaded into the hot rolling mill, and a roller mill is used to hot-roll it to the required cross-sectional size. The raw material is cooled and condensed, and then the stretcher is used to stretch it to the required size of the finished product.
Classification of hot rolled seamless steel pipes and cold rolled seamless steel tubes
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, etc.
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 (rolled) seamless steel pipes also include carbon thin-walled steel pipes, alloy thin-walled steel pipes, Stainless thin-walled steel pipes, special-shaped steel pipes. The outer diameter of hot-rolled seamless steel pipes is generally greater than 32mm, and the wall thickness is 2.5-75mm. The outer diameter of cold-rolled seamless steel pipes can be up to 6mm, and the wall thickness can be up to 0.25mm. The outer diameter of thin-walled pipes can be up to 5mm, and the wall thickness is less than 0.25mm. Cold rolling has higher dimensional accuracy than hot rolling.
The main production processes of hot rolled seamless steel tubes
Preparation and inspection of tube blank → heating of tube blank → perforation → pipe rolling → steel pipe reheating → diameter determination (reduction) → heat treatment → finished pipe straightening → finishing → inspection (non-destructive, physical and chemical, Taiwan inspection) → warehousing
The delivery state of hot rolled seamless steel tubes is generally in a hot-rolled state after heat treatment. After passing the quality inspection, the hot rolled seamless steel pipe must undergo strict manual selection by the staff. After the quality inspection, the surface must be oiled, followed by multiple cold drawing experiments. After the hot rolling treatment, a perforation experiment must be performed. If the diameter of the perforation is too large, it needs to be straightened. After straightening, it is transferred to the flaw detection machine by the transmission device for flaw detection experiments. Finally, labels are affixed, specifications are arranged, and then placed in the warehouse.
Round tube blank → heating → piercing → three-roll cross rolling, continuous rolling or extrusion → tube removal → sizing (or diameter reduction) → cooling → straightening → hydraulic test (or flaw detection) → marking → warehousing Seamless steel pipes are made from steel ingots or solid tube blanks that are perforated into capillary tubes, and then hot rolled, cold rolled or cold drawn. The specifications of seamless steel pipes are expressed in terms of outer diameter * wall thickness in millimeters.
