Stainless steel seamless pipe is a kind of long steel with hollow section and no joint around. The thicker the wall thickness is, the more economical and practical it will be. The thinner the wall thickness is, the higher the processing cost will be.
Stainless steel seamless tube is resistant to air, steam, water and other weak corrosive medium and acid, alkali, salt and other chemical corrosive medium corrosion steel tube.Also known as stainless acid - resistant steel pipe.
The corrosion resistance of seamless stainless steel tubes depends on the alloying elements contained in the steel.Chromium is the basic element that enables stainless steel to obtain corrosion resistance. When the content of chromium in steel reaches about 12%, the oxygen of chromium and corrosion medium interact to form a very thin oxide film (self-passivation film) on the steel surface, which can prevent further corrosion of the steel matrix.In addition to chromium, stainless steel seamless tube commonly used alloy elements nickel, molybdenum, titanium, niobium, copper, nitrogen and so on, in order to meet the various USES of stainless steel structure and performance requirements.
Stainless steel seamless pipe is a kind of hollow long round steel, which is widely used in petroleum, chemical, medical, food, light industry, mechanical instrument and other industrial transmission pipes and mechanical structural components. 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 all kinds of conventional weapons, barrels, shells, etc.
As seamless steel pipe has good comprehensive performance, it is widely used in chemical industry, construction, water supply, drainage, petroleum, light and heavy industry, refrigeration, sanitation, water heating, fire protection, power, aerospace, shipbuilding and other basic engineering.
According to rolling method, stainless steel pipe can be divided into hot rolling, hot extrusion and cold drawing (rolling).
According to the different microstructure of stainless steel, it can be divided into semi ferritic semi martensitic stainless steel seamless pipe, martensitic stainless steel seamless pipe, austenitic stainless steel seamless pipe, austenitic ferritic stainless steel seamless pipe, etc.
Manufacturing process of stainless steel seamless pipe
1. Hot rolling (extrusion of seamless steel tube): round tube blank → heating → piercing → three roll cross rolling, continuous rolling or extrusion → pipe stripping → sizing (or reducing) → cooling → straightening → hydrostatic test (or flaw detection) → marking → warehousing
2. Cold drawing (rolling) seamless steel pipe: round tube blank → heating → piercing → heading → annealing → pickling → oiling (copper plating) → multi pass cold drawing (cold rolling) → blank tube → heat treatment → straightening → hydrostatic test (flaw detection) → marking → warehousing.
1. Chemical analysis: chemical analysis shall be carried out for the chemical composition of the material, and the chemical composition shall meet the requirements of the standard.
2. Air pressure and water pressure test: the pressure pipe shall be put into the water pressure test one by one, and the specified pressure value shall not be kept for less than 5 seconds without leakage. The normal supply water pressure test is 2.45mpa, and the air pressure test is p = 0.5mpaa.
3. Corrosion test: the industrial corrosion-resistant steel pipes supplied shall be tested for corrosion resistance according to the standard provisions or the corrosion method agreed by both parties, and there shall be no tendency of intergranular corrosion.
4. Process performance inspection: flattening test, tensile test, impact test, flaring test, hardness test, metallographic test, bending test, NDT (including eddy current test, X-ray test and ultrasonic test).
5. Theoretical weight:
Cr Ni austenitic stainless steel w = 0.02491s (D-S)
Cr Ni Mo austenitic stainless steel (kg / M) s-wall thickness (mm)
D- outer diameter (mm)
grade of steel