316L stainless steel welded pipe and 2205 duplex stainless steel welded pipe are two different materials. What is the difference between them? 2205 duplex stainless steel pipe has a history of 80 years. Nitrogen is added to the material of 2205 stainless steel pipe to improve local corrosion resistance. Its solid solution structure contains about half of the ferrite and austenite phases, and generally the least compatible content It also needs to reach 30%, so it has the performance characteristics of ferritic and austenitic stainless steel.Compared with austenitic 316L steel pipe, 2205 duplex stainless steel pipe has the following advantages.1. The yield strength is more than twice that of 316L austenitic stainless steel, and it has sufficient plastic toughness for forming. The wall thickness of pressure vessel made of 2205 stainless steel pipe is 30-50% less than that of 316L stainless steel pipe, which is beneficial to reduce costs.2. 2205 steel pipe has excellent resistance to stress corrosion cracking, especially in the marine environment containing chloride ions, stress corrosion is difficult to solve the outstanding problem of austenitic stainless steel.3. The general corrosion resistance of 2205 duplex steel used in many media is due to ordinary 316L stainless steel, and super duplex stainless steel has extremely high corrosion resistance. For example, it can even replace high-alloy austenitic stainless steel in acetic acid, formic acid, etc. Tubes, and even corrosion-resistant alloys.4. It has good local corrosion resistance. Compared with austenitic stainless steel with the same alloy content, in view of the high strength and good corrosion resistance of 2205 duplex stainless steel, its wear corrosion resistance and corrosion fatigue performance are due to general 316L austenitic stainless steel.5. The coefficient of linear expansion is lower than that of austenitic stainless steel, which is close to that of carbon steel. It is suitable for carbon steel connection and has important engineering significance.6. No matter under the conditions of dynamic or static load, it has higher energy absorption capacity than 316L stainless steel pipe. This has obvious practical application value for structural parts or pipelines to deal with sudden collisions, explosions, etc., the advantages of 2205 stainless steel pipe.Compared with 316L stainless steel pipe, the disadvantages of 2205 stainless steel pipe are as follows;1. The universality and versatility of application are not as good as 316L austenitic stainless steel. For example, for long-term application, the temperature of the medium used must be controlled below 250 degrees.2. Its plastic toughness is lower than that of 316L stainless steel, and its cold and hot processing technology and forming performance are poor.3. There is medium temperature brittleness, and it is necessary to strictly control the heat treatment and welding process system to avoid harmful interactions and damage performance.The main reason for the disadvantage of duplex stainless steel compared with austenitic stainless steel is that duplex stainless steel contains a large amount of ferrite structure.
Eastking Steel has a large stock of 2304, 2205 and 2507 duplex stainless steel plates to choose from, which is sufficient to meet your strict requirements for corrosion resistance and high strength.Duplex stainless steel is a stainless steel sheet with a relatively high chromium content (between 18% and 28%) and an appropriate amount of nickel (between 4.5% and 8%). The almost equal content of ferrite and austenite forms a balanced (two-phase) microstructure, combined with its chemical composition can explain its strong corrosion resistance and excellent mechanical properties. Alloys 2304 and 2205 are the most common grades. The ability to resist chloride stress corrosion cracking is another significant feature of this stainless steel sheet.Compared with ordinary austenitic or duplex stainless steels, super duplex stainless steels have stronger pitting and crevice corrosion resistance. This is because chromium, molybdenum and nitrogen are further added to this grade. Alloy 2507 is the most common super duplex grade.
1. Chemical polishingChemical polishing is a commonly used surface treatment process for stainless steel. Compared with the electrochemical polishing process, its biggest advantage is that it does not require a DC power supply and special fixtures. It can polish parts with complex shapes and has high productivity. In terms of functionality, chemical polishing can not only obtain a physically and chemically clean surface, but also remove the mechanical damage layer and stress layer on the surface of stainless steel to obtain a mechanically clean surface, which helps prevent local corrosion of parts and improve Mechanical strength, prolong the service life of parts. Since the patent on chemical polishing of stainless steel was issued in the early 1940s, many formulas have been published so far, but people still find it difficult to apply them in practice. Because there are many varieties of stainless steel, and different grades of stainless steel have different corrosion laws, it is impossible to use the same solution, so there are many types of stainless steel chemical polishing solutions.The basic composition of chemical polishing solution includes corrosive agent, oxidizer and water. Corrosive agent is the main ingredient, if stainless steel is dissolved in the solution, polishing cannot be performed. Oxidizers and additives can inhibit the process and make the reaction proceed in a direction favorable to polishing. Water regulates the concentration of the solution and facilitates the diffusion of reaction products. Whether the chemical polishing of stainless steel can proceed smoothly depends on the reasonable combination of the above components.2. Electrolytic polishingStainless steel electrolytic polishing is to hang stainless steel products on the anode and perform anode electrolytic processing in the electrolytic polishing solution. Electrolytic polishing is a special anode process. In the entire anode electrolytic polishing process, the surface of stainless steel products undergoes two contradictory processes at the same time, that is, the continuous formation and dissolution of oxide film on the metal surface. However, the conditions for the chemical film formation of the protruding parts and depressions on the surface of stainless steel products to enter the passive state are different, and due to anode dissolution, the concentration of metal salt in the anode area continues to increase, forming a high resistivity consistency on the surface of stainless steel products Mucosal layer. The thickness of the viscous mucosa at the microscopic unevenness of the product surface is different, and the anode microscopic surface current is unevenly distributed. The current density at the microscopic protrusions is high and the dissolution is faster, so that the burrs or microscopic protrusions on the surface of the product are preferentially dissolved to achieve leveling; the current density at the depressions is lower and the dissolution is slower. Due to the different current density distribution, the surface of the product continuously forms and dissolves at different rates. The anode surface undergoes two opposite processes at the same time, film formation and dissolution, and the continuous generation and dissolution of the passive film, so that the surface of the stainless steel product is leveled to achieve a highly smooth and glossy appearance, which satisfies the purpose of polishing and finishing the surface of the stainless steel product.
The principle of making 8k mirror stainless steel plate is that the stainless steel raw material is polished on the surface of the steel plate through the polishing equipment with the abrasive liquid, so that the surface of the plate is flat and the brightness is as clear as a mirror. Stainless steel mirror panel products are widely used in building decoration, elevator decoration, industrial decoration, facility decoration and other decoration projects.The process of stainless steel mirror panel processing can be divided into two methods: normal grinding and fine grinding. Which of these two processing methods produces a better mirror effect? And this must be judged by looking at the brightness of the mirror surface, and the blisters and grinding heads on the surface of the sheet must be less. Generally speaking, stainless steel plates are processed on a polishing machine. The slower the traveling speed, the more groups of grinding, and this effect will be very good; when stainless steel plates are processed by polishing equipment, the first thing to do is to The plate is sanded, and then the stainless steel plate is put into the grinding fluid, which needs to be ground through 8 groups of grinding heads with different thicknesses. The grinding process is basically the surface treatment of the stainless steel plate. There is no depth in this process. This step is mainly for Remove the oxide layer on the surface of the stainless steel plate.After finishing the above process, it can be washed and dried. The color stainless steel mirror panel is colored on the basis of the stainless steel mirror panel. Now the high-end color stainless steel mirror panel is processed by vacuum ion plating technology. It is even possible to perform pattern etching on the mirror panel, and various patterns and styles of pattern etching plates can be obtained.