Stainless steel seamless steel pipe is a long steel material with a hollow section and no seams around it. It is a steel pipe that is resistant to corrosion by weakly corrosive media such as air, steam, and water, and chemically corrosive media such as acids, alkali, and salts. Also known as stainless acid-resistant steel pipe.
Stainless steel seamless steel pipe is a long steel material with a hollow section and no seams around it. It is a steel pipe that is resistant to corrosion by weakly corrosive media such as air, steam, and water, and chemically corrosive media such as acids, alkali, and salts. Also known as stainless acid-resistant steel pipe.
Features
1. First, the thicker the wall thickness of the product, the more economical and practical it is. The thinner the wall thickness, the processing cost will increase significantly;
2. The process of this product determines its limited performance. Generally, seamless steel pipes have low precision: uneven wall thickness, low brightness of the inner and outer surfaces of the pipe, high cost of sizing, and pitting and black spots on the inner and outer surfaces that are difficult to remove;
3. Its detection and shaping must be processed offline. Therefore, it reflects its superiority in terms of high pressure, high strength, and mechanical structural materials.
Stainless steel seamless pipes are steel pipes that are resistant to corrosion by weakly corrosive media such as air, steam, and water and chemically corrosive media such as acids, alkalis, and salts. Also known as stainless acid-resistant steel pipe.
The corrosion resistance of stainless steel seamless pipes depends on the alloying elements contained in the steel. Chromium is the basic element that makes stainless steel corrosion resistant. When the chromium content in steel reaches about 12%, chromium interacts with the oxygen in the corrosive medium to form a thin oxide film (self-passivation film) on the surface of the steel. , which can prevent further corrosion of the steel matrix. In addition to chromium, commonly used alloy elements for stainless steel seamless pipes include nickel, molybdenum, titanium, niobium, copper, nitrogen, etc. to meet the requirements for the structure and performance of stainless steel for various purposes.
Stainless steel seamless pipe is a hollow long circular steel material that is widely used in industrial transportation pipelines and mechanical structural components such as petroleum, chemical industry, medical, food, light industry, mechanical instrumentation, etc. In addition, when the bending and torsional strength are the same, the weight is lighter, so it is also widely used in manufacturing mechanical parts and engineering structures. It is also commonly used to produce various conventional weapons, gun barrels, artillery shells, etc.
type
According to the rolling method, it is divided into hot rolling, hot extrusion and cold drawn (rolled) stainless steel pipes.
According to the different metallographic structures of stainless steel, it can be divided into semi-ferritic and semi-martensitic stainless steel pipes, martensitic stainless steel pipes, austenitic stainless steel pipes, austenitic-ferritic iron stainless steel pipes, etc.
Production process
1. Hot rolling (extruded seamless steel pipe): round tube blank → heating → perforation → three-roll cross rolling, continuous rolling or extrusion → tube removal → sizing (or diameter reduction) → cooling → straightening → hydraulic test (or flaw detection) → Mark → Warehouse.
The raw material for rolling seamless pipes is round tube billet. The round tube billet must be 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 to a temperature of approximately 1,200 degrees Celsius. The fuel is hydrogen or acetylene. Temperature control in the furnace is a key issue. After the round tube comes out of the furnace, it must be pierced through a pressure punching machine. Generally, the more common piercing machine is the tapered roller piercing machine. This type of piercing machine has high production efficiency, good product quality, large perforation diameter expansion, and can penetrate a variety of steel types. After perforation, the round tube blank is successively cross-rolled, continuous rolled or extruded by three rollers. After extrusion, the pipe must be removed and calibrated. The sizing machine rotates a tapered drill bit at high speed into the steel blank to drill holes 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 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 a metal flaw detector (or hydraulic test) by a conveyor belt for internal flaw detection. If there are cracks, bubbles and other problems inside the steel pipe, they will be detected. After quality inspection, steel pipes must undergo strict manual selection. After the quality inspection of the steel pipe, spray the serial number, specification, production batch number, etc. with paint. And it is hoisted into the warehouse by a crane.
2. Cold drawn (rolled) seamless steel pipe: round tube blank → heating → perforation → heading → annealing → pickling → oiling (copper plating) → multi-pass cold drawing (cold rolling) → billet tube → heat treatment → straightening →Hydraulic test (flaw detection)→Marking→Storage.
The rolling method of cold-drawn (rolled) seamless steel pipe is more complicated than 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 round tube blank is hollowed out, it needs to be headed and annealed. After annealing, special acidic liquid should be used for pickling. After pickling, apply oil. Then it is followed by multiple passes of cold drawing (cold rolling) and then special heat treatment. After heat treatment, it is treated in the same way as the steel pipe cooling process.
