Seamless steel pipes can be divided into hot rolled seamless steel pipes, hot expanded seamless steel pipes, and cold drawn seamless steel pipes according to different production processes. There are four categories of cold rolled seamless steel pipes.
The hot rolled seamless steel pipe is a round steel that is pierced into a tube billet by a piercing machine, and then passed through a hot rolling mill to set the outer diameter of the tube billet to form a finished hot rolled seamless steel tube. The process is simple and the price is relatively low, but the dimensional precision is not high. Domestic production technology can be hot rolled for seamless steel pipes with an outer diameter of 60mm to 600mm.
The hot expanded seamless steel pipe is formed by using the seamless steel pipe billet or the finished seamless steel pipe to be heated to more than 1050 degrees in an electric furnace, and then expanded with an alloy core head to a certain outer diameter. After being expanded into a hot expanded seamless steel pipe, the wall thickness is thinner than the raw material, the length is shortened, and the outer diameter is larger.
Cold drawn seamless steel pipe is a seamless steel pipe that is formed by drawing a seamless steel pipe blank or a finished seamless steel pipe by the grinding tool of a cold drawing machine. It is exactly opposite to the process of thermal expansion, and the drawn finished pipe is longer than the raw material. Yes, the wall thickness is thinner, and the outer diameter is smaller. The drawing process does not require heating, forming at room temperature, and can also be re annealed, sometimes it is not necessary to anneal.
The cold rolling process is also produced at room temperature like the cold drawing process, except that the cold rolling mill is different from the cold drawing machine. Production is slower than cold drawn process production.
