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The rolling method is divided into hot rolling, hot extrusion and cold drawing (rolling) of 304 stainless steel seamless pipe. According to the metallographic structure of 304 stainless steel seamless pipe, it is divided into semi-ferrite and semi-martensitic 304 stainless steel seamless pipe, martensitic 304 stainless steel seamless pipe, austenitic 304 stainless steel seamless pipe, austenite -Ferritic 304 stainless steel seamless pipe.
1, Hot rolling (extruded seamless steel pipe): round pipe billet → heating → perforation → three-roll diagonal rolling, continuous rolling or extrusion → stripping → sizing (or reducing) → cooling → straightening → hydraulic pressure Test (or flaw detection) → mark
2, The rolling method of cold drawn (rolled) seamless steel pipe is more complicated than that of hot rolled (extruded seamless steel pipe). The first three steps of their production process are basically the same. The difference starts from the fourth step. After the blank tube has been emptied, it must be started and annealed. After annealing, a special acid liquid is used for pickling.
After pickling, apply oil. Then it is followed by multiple passes of cold drawing (cold rolling) and then blanking, and special heat treatment. After heat treatment, it is straightened.
After being straightened, the steel pipe is sent from the conveyor belt to a metal flaw detector (or hydraulic test) for internal flaw detection. Problems such as cracks and bubbles inside the steel tube will be detected.
After the quality inspection of the steel pipe, spray paint with the number, specifications, production batch number, etc.