Definition of stainless steel seamless pipe

Stainless steel seamless steel pipe is a kind of long steel with hollow section no joint around. Stainless steel seamless pipe

Features of stainless steel seamless pipe:

First of all, the thicker the wall thickness of the product, the more economical practical. The thinner the wall thickness, the higher the processing cost. Secondly, the process of the product determines its limited performance. Generally, the accuracy of seamless steel pipe is low: the wall thickness is uneven, the brightness inside outside of the pipe is low, the shaping cost is high, there are pitting black spots inside outside. It is easy to remove; third, its detection shaping should be processed offline. Therefore, in the high-pressure, high-strength mechanical structure material reflects its advantages.

Type of stainless steel pipe:

The rolling methods include hot rolling, hot extrusion cold drawing (rolling) of stainless steel pipes.

According to the metallographic structure of stainless steel, it can be divided into semi Ferritic semi martensitic stainless steel pipe, martensitic stainless steel pipe, austenitic stainless steel pipe, austenitic ferrite iron stainless steel pipe, etc.

1. Hot rolling (extrusion seamless steel pipe): round tube blank → heating → piercing → three roll cross rolling, continuous rolling extrusion → pipe dismantling → sizing ( reducing diameter) → cooling → straightening → hydraulic test ( defect) detection → marking → storage

The raw material for rolling seamless pipe is round billet. The tube blank is cut into pieces about 1 meter long by cutting machine sent to furnace for heating through conveyor belt. The blank is fed into the furnace to be heated at a temperature of about 1200 ℃. The fuel is hydrogen acetylene. The temperature control in the furnace is the key problem. After the tube blank is released, it needs to pass through the pressure piercer. A more common piercer is a tapered roller piercer. This kind of punching machine has high production efficiency, good product quality, large hole diameter can grind various kinds of steel. After piercing, the tube blank is rolled, rolled extruded in three rolls. After extrusion, the pipe shall be calibrated. The sizing machine rotates into the steel blank at high speed through a conical bit to form a steel pipe. The inner diameter of the steel pipe is determined by the outer diameter length of the drill bit of the sizing machine. After sizing, the steel pipe enters the cooling tower is cooled by spraying water. After cooling, straighten the steel pipe.

2. Cold drawn (rolled) seamless steel pipe: round billet → heating → piercing → heading → annealing → pickling → oiling (copper plating) → multi pass cold drawing (cold rolling) → billet tube → heat treatment → straightening → hydrostatic test (flaw detection) → marking → warehousing.

The rolling method of cold drawn (rolled) seamless steel pipe is more complicated than that of hot rolling (extrusion) seamless steel pipe. The first three steps of their production process are basically the same. The difference starts with step four. After the tube blank is hollowed out, it needs to be headed annealed. After annealing, it is absorbed by acid liquid. After pickling, oil. Cold rolling followed by hot drawing. After heat treatment, straighten it. After straightening, the steel pipe is sent to the metal flaw detector through the conveyor belt for internal flaw detection. If there are cracks bubbles inside the steel pipe, it will be detected. After the quality inspection of the steel pipe, it is selected by strict manual. After the quality inspection of steel pipe, spray paint, number, specification, production batch number, etc., hoist it into the warehouse by crane.