Introduction of Stainless Steel Seamless Pipe:
Stainless Steel Seamless Pipe is a kind of long steel with a hollow cross section and no seams around it. Generally speaking, the thicker the wall thickness, the more economical and practical it is; while the thinner the wall thickness, the processing cost will increase significantly.
Stainless Steel Seamless Tube Production Manufacturing Methods:
Stainless steel seamless tube production methods are diverse, mainly including hot rolling, cold rolling, cold drawing and extrusion processes. Different production methods are suitable for the manufacture of seamless pipes of different specifications and uses.
1. Hot rolling method
Hot rolling method is a common process for the production of stainless steel seamless pipe, suitable for manufacturing large size, thick-walled seamless pipe. The production process is as follows:
(1) Raw material preparation: select high-quality stainless steel pipe billets, inspect and remove surface defects, and cut to the required length.
(2) Heating and piercing: After the billet is heated to a high temperature, it is pierced on a piercing machine to form a hollow tube.
(3) Rolling and sizing: the rough pipe continues to be rolled on the automatic pipe rolling machine, the wall thickness is adjusted through the equalizing machine, and finally the pipe is sized on the sizing machine to meet the specifications.
(4) Cooling and straightening: After rolling, the steel pipe is cooled by water spraying from cooling tower, and then straightened.
(5) Quality inspection and storage: steel pipes are subject to hydrostatic test or flaw detection, and after passing, they are marked and put into storage.
The advantages of hot rolling method are high production efficiency and low cost, but the dimensional accuracy and surface finish are relatively low.
2. Cold Rolling and Cold Drawing
Cold Rolling and Cold Drawing are mainly used to produce seamless tubes with smaller size, thinner wall thickness and higher quality. The process is as follows:
(1) Pretreatment: After the billet is heated and pierced, it is subjected to beating, annealing and pickling.
(2) Cold working: multiple passes are carried out on the cold drawing machine or cold rolling mill to gradually adjust the pipe size.
(3) Heat treatment and straightening: After cold working, the steel pipe needs to be heat treated to restore its mechanical properties, followed by straightening.
(4) Quality inspection and warehousing: steel pipes are subject to strict flaw detection, size measurement and appearance inspection, and are labeled and warehoused after passing.
The advantages of cold rolling and cold drawing methods are high dimensional accuracy and good surface finish, but the production cost is higher.
3. Extrusion method
Extrusion method is carried out by placing a heated billet into a closed extrusion cylinder and extruding the billet out of the die holes under the action of piercing rods and extrusion rods. This method is suitable for the production of seamless tubes with small diameters.
The advantage of the extrusion method is that complex shapes and small diameters of pipes can be produced, but the production efficiency is relatively low.
Stainless steel seamless pipe classification:
1, according to the manufacturing process can be divided into hot rolled pipe, cold rolled pipe, cold drawn pipe and extruded pipe.
2, according to the shape of the cross-section, can be divided into round tube and shaped tube, of which the round tube is most widely used.
Seamless Stainless Steel Tubes Common Materials
Seamless Stainless Steel Tubes can be divided into several series and grades according to the chemical composition and performance characteristics. The following is a detailed introduction of common materials:
1. 200 series
(1) 201 (1Cr17Mn6Ni5N)
A: Chemical composition: C ≤ 0.15, Si ≤ 1.00, Mn 5.5-7.5, P ≤ 0.060, S ≤ 0.030, Ni 3.5-5.5, Cr 16.0-18.0, N ≤ 0.25.
B: Performance characteristics: 201 Stainless Steel It is a kind of low-nickel austenitic stainless steel with certain acid and alkali resistance, high density, no bubbles and pinholes after polishing. Due to its low cost, it is widely used in decorative tubes, industrial tubes and shallow drawn products.
C: Application areas: commonly used in the production of watch cases, watch bands, kitchen utensils, sinks, etc..
(2) 202 (1Cr18Mn8Ni5N)
A: Chemical composition: similar to 201, but with higher manganese content, usually around 8%.
B: Performance characteristics: compared with 201, 202 has better strength and toughness, but corrosion resistance is slightly inferior to 300 series.
C: Application areas: mainly used in building decoration, furniture and other fields.
2. 300 series
(1) 301 (1Cr17Ni7)
A: Chemical composition: C ≤ 0.15, Si ≤ 1.00, Mn ≤ 2.00, P ≤ 0.045, S ≤ 0.030, Ni 6.5-8.0, Cr 16.0-18.0.
B: Performance characteristics: 301 stainless steel has good corrosion resistance and molding, but the strength is higher, suitable for deep-drawn machining C: Application areas: commonly used in the manufacture of stainless steel.
C: Application areas: commonly used in the manufacture of tableware, kitchen equipment, automotive parts and so on.
(2) 302 (1Cr18Ni)
Chemical composition: similar to 301, but with higher chromium content.
B: Performance characteristics: corrosion resistance is better than 301, suitable for use in harsher environments.
C: Application: used in the manufacture of tableware, chemical equipment, etc..
(3) 304 (0Cr18Ni9)
A: Chemical composition: C ≤ 0.08, Si ≤ 1.00, Mn ≤ 2.00, P ≤ 0.045, S ≤ 0.030, Ni 8.0-10.5, Cr 18.0-20.0.
B: Performance characteristics: 304 is the most widely used stainless steel material, with good corrosion resistance, heat resistance and low temperature performance.
C: Application areas: widely used in food processing equipment, chemical equipment, medical equipment and so on.
(4) 304L (00Cr19Ni10)
A: Chemical composition: ultra-low carbon version of 304, C ≤ 0.03.
B: Performance characteristics: better intergranular corrosion resistance than 304, suitable for welding applications.
C: Application areas: commonly used in chemical vessels, pipelines, etc..
(5) 321 (1Cr18Ni9Ti)
A: Chemical composition: similar to 304, but with added titanium.
B: Performance characteristics: excellent intergranular corrosion resistance, high temperature strength.
C: Application areas: used in aviation, chemical, automotive and other fields.
(6) 316 (0Cr17Ni12Mo2)
A: Chemical composition: C ≤ 0.08, Si ≤ 1.00, Mn ≤ 2.00, P ≤ 0.045, S ≤ 0.030, Ni 10.0-14.0, Cr 16.0-18.0, Mo 2.0-3.0.
B: Performance characteristics: corrosion resistance is better than 304, especially for chloride ion resistance Stronger.
C: Application: Widely used in marine equipment, chemical equipment, medical equipment and so on.
(7) 316L (0Cr17Ni14Mo2)
A: Chemical composition: ultra-low carbon version of 316, C ≤ 0.03.
B: Performance characteristics: excellent resistance to intergranular corrosion, suitable for welding.
C: Application areas: used in chemical pipelines, marine engineering, etc..
(8) 310S (0Cr25Ni20)
A: Chemical composition: C ≤ 0.08, Si ≤ 1.50, Mn ≤ 2.00, P ≤ 0.045, S ≤ 0.030, Ni 19.0-22.0, Cr 24.0-26.0.
B: Performance characteristics: excellent resistance to high temperatures, suitable for use in high temperature environments.
C: Application areas: used in boilers, heat exchangers and so on.
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