Four production processes of seamless steel pipes

According to different production processes, seamless steel pipes can be divided into four categories: hot-rolled seamless steel pipes, hot-expanded seamless steel pipes, cold-drawn seamless steel pipes, and cold-rolled seamless steel pipes.

1. Hot-rolled seamless steel pipes are made by punching round steel into tube blanks through a punching machine, and then the tube blanks are customized into the required outer diameter through a hot rolling machine, and then formed into hot-rolled seamless steel pipe products. The process is simple and the price is relatively low, but the dimensional accuracy is not high.

2. Hot-expanded seamless steel pipes are made by burning seamless steel pipe blanks or finished seamless steel pipes in an electric furnace to above 1050 degrees, and then expanding them to a certain outer diameter with an alloy core. After expanding into hot-expanded seamless steel pipes, the wall thickness is thinner than the raw material, the length is shortened, and the outer diameter becomes larger.

3. Cold-drawn seamless steel pipes are seamless steel pipes formed by drawing seamless steel pipe blanks or finished seamless steel pipes through the mold of a cold drawing machine. It is consistent with the hot expansion process. The finished pipe after drawing is longer than the raw material, the wall thickness is thinner, and the outer diameter is smaller. The drawing process does not require heating and can be formed at room temperature. It can also be re-annealed, but sometimes annealing is not necessary.

4. The cold rolling process is also produced at room temperature like the cold drawing process, but the cold rolling machine is different from the cold drawing machine. The cold drawing machine is formed by a mold, while the cold rolling machine is gradually formed by a mold, so the cold rolling process is slower than the cold drawing process.