Hot rolling process of seamless steel pipe

1. Manufacturing and processing methods of seamless steel pipes:

(1) Hot rolling (extruded seamless steel tube): round tube billet→heating and piercing→three-roll cross-rolling, continuous rolling or extrusion and one-off tube→sizing (or reducing)→cooling→straightening→hydraulic pressure Test (or flaw detection) → mark → warehousing (2) cold drawn (rolled) seamless steel pipe: round tube billet → heating → piercing → heading → annealing → pickling → oiling (copper plating) → multi-pass cold drawing ( Cold rolling)→Heat treatment of blank tube→Straightening→Hydraulic test (flaw detection)→Marking→Warehousing

2. Hot rolled

Hot rolling is relative to cold rolling. Cold rolling is rolling below the recrystallization temperature, and hot rolling is rolling above the recrystallization temperature.

3. Rolling mill composition:

The hot strip rolling mill consists of a roughing mill and a finishing mill. The rough rolling mill consists of three types: semi-continuous, 3/4 continuous, and full-continuous: ①The semi-continuous one has a scale-breaking (removing oxide scale) stand and a reversible stand with vertical rolls; ②3/ 4 In the continuous type, in addition to the above-mentioned racks, there are also 2 serially arranged racks; ③The full continuous type is composed of 6 to 7 racks. The finishing mills are all composed of 5 to 7 continuously arranged racks and coilers. Hot strip rolling mills are named according to the length of the roll body. Those with a length of 914mm or more are called wide-band steel mills. Finishing mill work rolls with a length of 1700mm are called 1700mm hot strip rolling mills, which can produce 1550mm wide strip coils. There are four methods for hot strip rolling according to product width and production process: wide strip hot rolling, wide strip hot rolling, narrow strip hot rolling, and planetary rolling mill hot strip rolling.