Shipbuilding
In daily life, people always refer to steel and iron together as "steel". It can be seen that steel and iron should be a kind of substance; in fact, from a scientific point of view, steel and iron have a little Different, their main components are all iron, but the amount of carbon contained is different. We usually call "pig iron" with a carbon content above 2%, and "steel" with a carbon content below this value. Therefore, in the process of smelting iron and steel, iron-containing ore is first smelted into molten pig iron in a blast furnace (blast furnace), and then the molten pig iron is put into a steelmaking furnace to be refined into steel. Then, steel (steel billet or strip) is used to make steel pipes, for example, carbon steel billets can be made into steel pipes with hollow sections through hot rolling and cold rolling processes (seamless tubes)
The manufacturing process of seamless steel tubes is mainly divided into two major steps:
1. Hot rolling (extruded seamless steel tube): round tube billet → heating → piercing → three-roll cross rolling, continuous rolling or extrusion → stripping → sizing (or reducing) → cooling → straightening → hydraulic test (or flaw detection) → marking → warehousing
2. Cold drawn (rolled) seamless steel tube: round tube blank→heating→piercing→heading→annealing→pickling→oiling (copper plating)→multi-pass cold drawing (cold rolling)→blank tube→heat treatment→straightening → hydrostatic test (flaw detection) → marking → storage.
