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Pros & Cons of Antibacterial Stainless Steel Seamless Tubes
May 24, 2022
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This technical article is talking about the pros and cons of antibacterial stainless steel seamless tubes.
The antibacterial stainless steel has good comprehensive performance, good appearance and surface characteristics. It has been widely used in all walks of life. The antibacterial stainless steel pipe is a hollow section of steel, which is generally divided into antibacterial stainless steel seamless pipes and welded pipes.
Advantages:
The forming speed is fast and the yield is high. It can be made into a variety of cross section forms, in order to meet the needs of the use conditions. Cold rolling can produce large plastic deformation of steel, thus raising the yield point of steel. Hot rolling can destroy the casting structure of steel ingot, refine the grain size of steel, and eliminate the defects of microstructure, so that the microstructure of steel is compact and the mechanical properties are improved.
Disadvantages:
1. Metal stratification – After the steel pipe is cold rolled, the steel internal non-metallic inclusions (mainly sulfide and oxide, and silicate) are pressed into thin sections, which causes the stratification (sandwich) phenomenon. Delamination greatly deteriorates the mechanical properties of steel along the thickness direction. It may cause interlaminar tearing when the weld expands.
2. Uneven wall thickness - we are familiar with metal with thermal expansion and cold contraction, due to rolling to the end of the cold rolled out of the steel pipe even in length and thickness are up to standard. Finally, there will be a certain negative difference after cooling. The greater the negative difference, the worse the uniformity of the wall thickness. Therefore, the wall thickness, length, straightness and ellipticity of cold rolled seamless antibacterial stainless steel tubes cannot be too precise.
3. Remain stress - due to uneven cooling, all kinds of cross-section steel pipes have residual stress. The greater the cross-section size of steel, the greater the residual stress. There is a certain impact on the performance under the action of external force. Such as deformation, stability, fatigue resistance and other aspects may have adverse effects.
4. Poor surface finish - the tensile marks on the inner surface of the steel pipe are longitudially distributed, showing symmetry or single straight line folding, some of which are of general length and some of which are local.
As a result of the complexity of the production process of the seamless steel pipes, the wall thickness uniformity is poor. Both the roughness of inside and outside wall surfaces is bad. The actual operation is very easy to make chloride (or sulfur ions) material (such as organic matter) binding on the antibacterial stainless steel wall. They form a local hypoxia acid environment, making the inner surface passivation membrane dissolved lost to the protection of the metal. The metal directly contact with the medium in the acidic environment. As anode loses electrons and forms hydroxide with water, the hydroxyl is replaced by chlorine root of hydroxide dissolved in water and decreases the anode passivation effect. As a cathode, the adhesive captures the hydrogen ions generated by the inner wall and forms hydrogen, which is discharged outward together with the reaction products of the inner wall metal. With the deepening of the reaction, the metal in the tube wall is constantly corroded away and forms pitting corrosion, which gradually deepens and increases. When the temperature rises above 50 degrees, pitting accelerates. The higher the temperature, the faster the pitting speed. Stress corrosion also occurs under high stress conditions and presents stress corrosion propagation characteristics. In addition, the seamless pipe in the welding process will produce a variety of unstable factors. It is not easy to be welded and impenetrable.
The antibacterial stainless steel has good comprehensive performance, good appearance and surface characteristics. It has been widely used in all walks of life. The antibacterial stainless steel pipe is a hollow section of steel, which is generally divided into antibacterial stainless steel seamless pipes and welded pipes.
Advantages:
The forming speed is fast and the yield is high. It can be made into a variety of cross section forms, in order to meet the needs of the use conditions. Cold rolling can produce large plastic deformation of steel, thus raising the yield point of steel. Hot rolling can destroy the casting structure of steel ingot, refine the grain size of steel, and eliminate the defects of microstructure, so that the microstructure of steel is compact and the mechanical properties are improved.
Disadvantages:
1. Metal stratification – After the steel pipe is cold rolled, the steel internal non-metallic inclusions (mainly sulfide and oxide, and silicate) are pressed into thin sections, which causes the stratification (sandwich) phenomenon. Delamination greatly deteriorates the mechanical properties of steel along the thickness direction. It may cause interlaminar tearing when the weld expands.
2. Uneven wall thickness - we are familiar with metal with thermal expansion and cold contraction, due to rolling to the end of the cold rolled out of the steel pipe even in length and thickness are up to standard. Finally, there will be a certain negative difference after cooling. The greater the negative difference, the worse the uniformity of the wall thickness. Therefore, the wall thickness, length, straightness and ellipticity of cold rolled seamless antibacterial stainless steel tubes cannot be too precise.
3. Remain stress - due to uneven cooling, all kinds of cross-section steel pipes have residual stress. The greater the cross-section size of steel, the greater the residual stress. There is a certain impact on the performance under the action of external force. Such as deformation, stability, fatigue resistance and other aspects may have adverse effects.
4. Poor surface finish - the tensile marks on the inner surface of the steel pipe are longitudially distributed, showing symmetry or single straight line folding, some of which are of general length and some of which are local.
As a result of the complexity of the production process of the seamless steel pipes, the wall thickness uniformity is poor. Both the roughness of inside and outside wall surfaces is bad. The actual operation is very easy to make chloride (or sulfur ions) material (such as organic matter) binding on the antibacterial stainless steel wall. They form a local hypoxia acid environment, making the inner surface passivation membrane dissolved lost to the protection of the metal. The metal directly contact with the medium in the acidic environment. As anode loses electrons and forms hydroxide with water, the hydroxyl is replaced by chlorine root of hydroxide dissolved in water and decreases the anode passivation effect. As a cathode, the adhesive captures the hydrogen ions generated by the inner wall and forms hydrogen, which is discharged outward together with the reaction products of the inner wall metal. With the deepening of the reaction, the metal in the tube wall is constantly corroded away and forms pitting corrosion, which gradually deepens and increases. When the temperature rises above 50 degrees, pitting accelerates. The higher the temperature, the faster the pitting speed. Stress corrosion also occurs under high stress conditions and presents stress corrosion propagation characteristics. In addition, the seamless pipe in the welding process will produce a variety of unstable factors. It is not easy to be welded and impenetrable.
