The manufacturing process of Austenitic Stainless Steel Seamless Tube :

1. Hot rolling: round tube billet → heating → piercing → three-roll cross rolling, continuous rolling or extrusion → tube stripping → sizing → cooling → straightening → hydraulic test → marking → storage.

The raw material for rolling seamless pipes is round pipe blanks. The round pipe blanks are cut by a cutting machine into a billet with a length of about 1 meter and sent to the furnace for heating via a conveyor belt. The billet is fed into the furnace and heated at a temperature of approximately 1200 degrees Celsius. The fuel is hydrogen or acetylene. The temperature control in the furnace is a key issue. After the round tube is out of the furnace, it must be pierced by a pressure piercing machine. After piercing, the round tube billet is successively cross-rolled, continuously rolled, or extruded by three rolls. After squeezing, take off the tube and calibrate.

A sizing machine is used to rotate a tapered drill bit into the steel blank to punch holes at a high speed to form a steel pipe. The inner diameter of the steel pipe is determined by the length of the outer diameter of the drill bit of the sizing machine. After the steel pipe is sized, it enters the cooling tower and is cooled by spraying water. After the steel pipe is cooled, it will be straightened. After straightening, the steel pipe is sent to the metal flaw detector by the conveyor belt for internal flaw detection. If there are cracks, bubbles, etc. inside the steel pipe, it will be detected. After the quality inspection of steel pipes, strict manual selection is required. After the quality inspection of the steel pipe, paint the serial number, specification, production batch number, etc. with paint. It is hoisted into the warehouse by a crane.

2. Cold rolling: round tube billet → heating → piercing → heading → annealing → pickling → oiling → multi-pass cold rolling → billet tube → heat treatment → straightening → hydraulic test → marking → storage.

The rolling method of cold-rolled seamless steel pipe is more complicated than that of hot rolling. The first three steps of their production process are the same. The difference starts in the fourth step. After the round tube blank is emptied, it must be heated and annealed. After annealing, use a special acid liquid for pickling. After pickling, apply oil. Then it is followed by multiple passes of cold rolling and then billeting, and special heat treatment. After heat treatment, it is straightened.