What are the factors affecting the corrosion of Jiangsu bimetal liner?

What are the factors affecting the corrosion of Jiangsu bimetal liner?

The selection of wear-resistant and anti-corrosion pipes and equipment is particularly important, which completely solves the problems of wear-resistant and anti-corrosion in the chemical industry, such as running, emitting, dripping and leaking. The following is a brief introduction to the use of Jiangsu bimetal liner in the chemical industry. 1、 Reasons for corrosion damage of Jiangsu bimetal liner: 1. Overtemperature and overpressure during operation, imperfect equipment management and careless thinking are also the main reasons for corrosion. 2. There are many corrosive media in chemical production, such as acid, alkali, salt, water, oxygen, etc., which is one of the main reasons for corrosion. 3. The unreasonable layout design, improper material selection, low manufacturing and processing quality, surplus welding, lack of anti-corrosion methods or poor construction quality of the bimetal composite liner provide an environment for corrosion damage. 2、 Connotative elements of corrosion damage of Jiangsu bimetal liner: 1. The rougher the appearance of the parts, the more likely they are to corrode. If the surface has oxide film, it is corrosion resistant. 2. Different metals have different corrosion resistance abilities with respect to different media. 3. Metal corrosion is fast at the places where the shape of equipment layout changes suddenly, such as openings, gaps or dead corners. 4. The coarser the metal grains, the faster the corrosion. On the contrary, the slower it is, for example, stainless steel has higher corrosion resistance than cast iron. 3、 Jiangsu bimetallic liner plate constitutes the external elements of corrosion damage: 1. The greater the external force or residual stress on the components of the bimetal composite liner, the faster the corrosion. 2. The type, chemical composition, concentration, pH value, impurities, moisture and oxygen content of the medium are the external causes of corrosion. 3. The faster the medium moves, the more likely it is to corrode. It will erode the protective film, causing vortex, turbulence and cavitation, leading to severe impact wear and cavitation corrosion. 4. Stress and fatigue. On the one hand, the occurrence of equipment stress is formed during processing, such as the deformation stress of cold processing and the arrangement stress of hot processing; On the other hand, the parts subject to pressure or rotation in the work will also cause stress. The effect of these stresses will lead to the internal distortion of the bimetallic composite liner, thus reducing the electrode potential of this part and aggravating the corrosion of the micro battery. 5. The higher the temperature and pressure of the medium, the faster the corrosion. As corrosion is a chemical reaction, the corrosion rate will be increased by 1-3 times for every 15% temperature rise. With the increase of temperature, the dispersion speed increases, and the resistance of electrolyte decreases, so the reaction of corrosive battery is accelerated. Jingjiang Yongxin Special Steel Co., Ltd. specializes in the production of bimetallic liner, mainly engaged in: Jiangsu bimetallic liner, bimetallic composite liner, rod mill liner, mining bimetallic composite liner, ball mill bimetallic composite liner, rod mill bimetallic composite liner, rod mill bimetallic liner, semi-automatic mill liner, super large ball mill bimetallic composite liner and other products. Welcome to consult and cooperate!

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What is the effect of high pressure deformation on bimetal composite liner?

High pressure deformation mainly by hydrostatic extrusion can improve the strength and plasticity of bimetal composite liner alloy at the same time, and reduce the brittle plastic transition temperature. These performance improvements may even be retained in subsequent processes. The research on the influence of high pressure deformation on the performance of Jiangsu bimetal liner is introduced. The research of various countries shows that the research situation and various mechanisms proposed by various countries to explore the reasons for high pressure deformation to improve the performance of bimetal liner materials are summarized. The mechanism of high pressure deformation on defect healing and the mechanism of dislocation pressure multilateralization proposed by Soviet scholars are first proposed. For the manufacture of bimetallic composite liner systems with a diameter of less than 10 microns, the traditional method of drawing by mold is difficult. The electrolytic corrosion method, which was successfully researched in the 1950s and then widely used, is effective in this case. Now, tungsten and tungsten rhenium bimetallic liner alloy (grades BAP5 and BP20) microfilaments with a diameter of 5-10 μ m have been prepared in batches by the above method, and the filaments with a diameter of 3-5 μ m have been prepared under laboratory conditions. The possibility of obtaining molybdenum and molybdenum rhenium alloy fine wires for lining plate was determined. The following technical data are the characteristics of industrial bilateral equipment for obtaining microfilaments with a diameter of 5-15 μ m by electrolytic corrosion. The purpose of improving the high temperature resistance of bimetal composite liner material is to meet the requirements of engine valves, turbine blades and rocket engine materials. A California researcher applied the coating method to retain the strength of the metal corresponding to half the melting point of the refractory metal. The metal used for lining plate is a series of electroformed refractory metals, including nickel, nickel drill and nickel manganese. The specific process is: adding particles with a diameter less than 1 μ M, such as thorium oxide or zirconia mixture, as coating materials. The proposal of the task When developing a thermionic diverter that converts flame heating directly into electrical energy, various possible bimetallic composite liner materials were studied. The results show that nickel base superalloy and more Jiangsu bimetal liner iron base alloys can meet the requirements of corrosion resistance, but their strength is not enough. In this regard, dispersion strengthened nickel based alloys or iron based alloys are slightly better.

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2020

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03

What is the fatigue strength of the bimetal liner?

High temperature fatigue refers to the process of bimetallic liner plate damage to the plate fracture due to the effect of cyclic and repeatedly changing stress under high temperature. Thermal fatigue refers to that when the temperature of bimetal composite liner changes and is constrained by external forces during heating and cooling, the internal expansion and contraction deformation of the liner corresponding to itself will produce stress and damage the Jiangsu bimetal liner. When heating and cooling repeatedly and rapidly, the stress will have impact, and the stress generated will be greater than that under normal conditions. At this time, some bimetal lining plates will be brittle. This phenomenon is called thermal shock. Thermal fatigue is similar to thermal shock, but the former is mainly accompanied by large plastic strain, while the latter is mainly brittle failure. The composition and heat treatment conditions of bimetal composite liner plate have influence on high temperature fatigue strength. Especially when the carbon content increases, the high temperature fatigue strength is obviously improved, and the solution heat treatment temperature also has a significant impact. Generally speaking, ferritic bimetallic liner has good thermal fatigue performance. In the austenitic Jiangsu bimetallic liner, the grades with high silicon and good extensibility at high temperatures have good thermal fatigue properties. The smaller the thermal expansion coefficient, the smaller the strain under the same thermal cycle, the smaller the deformation resistance and the higher the fracture strength, the longer the service life. It can be said that the fatigue life of martensitic bimetallic liner 1Cr17 is longer, while the fatigue life of austenitic liner plates such as 0Cr19Ni9, 0Cr23Ni13 and 2Cr25Ni20 is shorter. In addition, castings are more likely to be damaged due to thermal fatigue than forgings. At room temperature, the 107 times fatigue strength is 1/2 of the tensile strength. Compared with the fatigue strength at high temperature, there is not much difference in the fatigue strength from room temperature to high temperature.

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What should be paid attention to when the bimetal backing plate is welded through?

The temperature control of bimetal liner involves many parameters. The excitation frequency is inversely proportional to the square root of capacitance and inductance in the excitation circuit, or is proportional to the square root of voltage and current. The excitation frequency can be changed by changing the capacitance, inductance or voltage and current in the circuit. So as to control the welding temperature. Why should the cooling process of welded junction be good? Because of the milling of the welding end face of the bimetal backing plate, how to keep the end face clean, and the cooling process and time of the weld junction, these problems may not be shown from the weld junction. However, the inherent performance of the welded junction cannot be guaranteed. Therefore, the correct and effective implementation of welding procedures and operating procedures is crucial, and is closely related to the stability of welding equipment performance and the sense of responsibility of operators. In terms of electric fusion connection, it is not enough to ensure the stability of the transmission and discharge voltage of the electric fusion plate and the accuracy of the welding time. However, preparations before welding, such as whether the end face of the bimetal composite liner plate to be welded is clean, will definitely affect the welding effect if there are impurities. If the oxide layer is scraped, not scraped or not scraped enough, it is likely to cause the failure of welding. For low carbon steel, the welding temperature shall be controlled at 1250~1480 ℃, which can meet the requirements of 3~5mm plate wall thickness penetration. In addition, the welding temperature can also be realized by adjusting the welding speed. When the input heat is insufficient, the heated weld edge cannot reach the welding temperature, and the metal structure remains solid, forming incomplete fusion or incomplete penetration; When the input heat is insufficient, the heated weld edge exceeds the welding temperature, resulting in overburning or droplet, which causes the weld to form a cavity. After the two edges of the bimetal composite liner slab are heated to the welding temperature, the common metal grains are formed under the extrusion of the extrusion roller to penetrate and crystallize each other, resulting in a solid weld. If the extrusion force is too small, the number of common crystals formed will be small. The strength of weld metal decreases and cracks will occur after being stressed; If the extrusion force is too large, the molten metal will be extruded from the weld, which will not only reduce the strength of the weld, but also produce a large number of internal and external burrs, and even cause defects such as weld overlap. Whether the assembly of the electric fusion plate and the bimetal backing plate to be welded is correct will also affect the welding quality. In addition, whether the storage conditions of the electrofusion plate before welding meet the standards and whether the cooling process after welding is proper are all factors affecting the welding quality of the bimetal backing plate.

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