Characteristics of High Frequency Induction Welding of High-frequency Welding H-beam and Its Application in Dissimilar Metal Welding
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1 Huaxiaxin Metal Products Co., Ltd. High-frequency welding H-beam high-frequency induction welding development Huaxiaxin Metal Products Co., Ltd. High-frequency welding H-beam high frequency heating has been widely used in metal heat treatment, melting, welding and other aspects. Induction welding is the use of alternating magnetic field-electric field induction field eddy current effect on the work piece to heat the workpiece, so as to achieve a welding method. Welding equipment consists of AC power supply and induction heating coils. According to its frequency, AC power supply is divided into high-frequency welding H-beam high-frequency and medium-frequency. China Huaxiaxin Metal Products Co., Ltd. High-frequency welding H-beam high-frequency power supply has high frequency, fast heating, and wide application.
The induction coil is an important component of the induction heating equipment. The energy of the AC power supply is transmitted to the weldment by means of heating. It is usually made of copper tubes, and the water in the tubes is cooled during operation. Induction coil can be designed into a reasonable structure according to different needs, and has a major impact on the welding quality and production efficiency. Common structural forms include single-type, multi-spiral, flat, external heat, and internal heat. Induction heating power sources have appeared since the 1950s. They were: industrial frequency induction furnaces, medium frequency generators, and electronic tube oscillators. Huaxiaxin Metal Products Co., Ltd. High-frequency welding H-beam high-frequency power supply [11. 20th century The appearance of silicon thyristors at the end of the 1950s triggered a revolution in the technology of induction heating power supplies, and the rapid development of induction heating power supplies and their applications. By the 1980s, the invention of IGBT switching devices enabled the frequency of inductive power supplies to be as high as 100 kHz and power levels up to MW.
2 Huaxiaxin Metal Products Co., Ltd. Principles and characteristics of high-frequency welding H-beam high-frequency induction welding Huaxiaxin Metal Products Co., Ltd. High-frequency welding H-beam high-frequency induction heating is the use of Huaxiaxin Metal Products Co., Ltd. High-frequency welding H The Faraday electromagnetic effect and Joule effect of the high-frequency magnetic field generated by the high-frequency induction equipment of the section steel generate eddy currents on the surface of the material, and heat energy is generated by the heat energy generated by the eddy current. The induced current (unit: A) generated in the conductor in the alternating magnetic field of the coil is closed
I-den: 4.44BSfNxlO-4 a m ZZ, 7 where B is the magnetic induction intensity (unit: D; S is the cross-sectional area of ​​the work piece affected by the magnetic field (unit: cm2) expanded to the alternating current frequency (unit: Hz); N is the induction coil The number of turns, Z is the impedance of the workpiece (unit: Q) Due to the Joule effect, the relationship between the heat generated by the eddy current in the metallic material and the resistance and induced current of the metal is Q=t2RT (2) It can be known from equation (2). The amount of heat Q generated is proportional to the square of the frequency gate, so the higher the frequency of high-frequency induction of high-frequency welding H-beams in Huaxiaxin Metal Products Co., Ltd., the faster the heating speed.When the alternating current passes through the conductor, the current distribution is the center The density is small, and the closer to the surface density is, the higher the current frequency is, the lower the center of the conductor can be no current, but all concentrated on the surface of the conductor. This phenomenon is called Huaxiaxin Metal Products Co., Ltd. high-frequency welding H-beam high frequency The surface effect of the electric current.Because Hua Xiaxin Metal Products Co., Ltd. high-frequency welding H-beam high-frequency induction skin effect, usually take 85% of the current distribution of the conductor surface layer thickness is the current penetration depth, to characterize The strength of the surface effect is determined by the formula (3). Closed factory: 6 = 4.5x105, / ;; (3) PJ = the current penetration depth in the conductor (unit: m); P is the resistance of the conductor Coefficient (unit: Q·m);permeability of the conductor of anal conductor [unit:T/(A·m)] As can be seen from formula (3), the higher the frequency, the smaller the current penetration depth, then the heating thickness The thinner and concentrated the energy is, the surface layer of the workpiece is rapidly heated.The current density of the two adjacent metal conductors in the high-frequency magnetic field of high-frequency welding H-beams in Huaxiaxin Metal Products Co., Ltd. must be redistributed. On the contrary, the maximum value appears inside the conductor. Conversely, the maximum value appears outside the conductor. This phenomenon is called proximity effect.
The characteristics of high-frequency welding of high-frequency welding H-beams of Huaxiaxin Metal Products Co., Ltd. are as follows: (1) The heating speed is high and the production efficiency is high. Huaxiaxin Metal Products Co., Ltd. High-frequency welding H-beam high frequency induction heating unit power up to 500-1 000 kW Zhan, so the heating speed is very fast, a large area of ​​welding takes only a few seconds, can greatly shorten the welding time, improve productivity ,reduce manufacturing cost. (2) Small heat-affected zone and little damage to the substrate. Hua Xiaxin Metal Products Co., Ltd. high-frequency welding H-beam high-frequency induction heating skin effect makes the heating depth of the workpiece to be welded is very shallow, even up to a few tenths of a millimeter, just rely on the workpiece heat transfer to the core heat, any point of the workpiece When entering the sensor, it is rapidly heated to the melting temperature and leaves the inductor and enters a sharp cooling state. There is almost no holding time, and the heating time is very short. Therefore, the heat affected zone is very small and basically does not damage the substrate. In addition, very few oxide scales are produced. Even if heated in air, the surface of the billet is oxidized and decarburized very little.
(3) Avoid or reduce the formation of interfacial brittle compounds, and the mechanical properties of welded joints are excellent. Due to the high speed of induction heating, energy concentration, and short cooling time, the austenite grains obtained are fine, so that the induction-heated workpiece has a very good metallographic structure. For dissimilar metal welding, the formation of interfacial brittle compounds can be reduced due to the very short heating time, which can effectively improve the mechanical properties of welded joints. (4) to achieve a complex interface welding. The sensor heating head can be designed into a corresponding shape according to the heating needs of different workpieces. The extremely short heating time can achieve local heating, the temperature in the heating zone is quickly established, and the temperature transition area is narrow, so that the sensor can move along the complicated interface. To achieve a complex interface welding. In addition, Huaxiaxin Metal Products Co., Ltd. high-frequency welding H-beam high frequency induction heating welding also has the advantages of energy saving, reproducibility, and easy automation. The disadvantage is that the heating temperature is not easily controlled and the electromagnetic field generated is harmful to the human body.
3 Characteristics and methods of dissimilar metal welding There are many types of metal materials, and their advantages and disadvantages are different. In order to give full play to the advantages of different materials, modern industries often require the use of dissimilar metals, which is of great significance for improving the performance of materials and the effective use of metal resources. Aluminum and its alloys have low density, high specific strength, and are excellent in corrosion resistance, electrical conductivity, and thermal conductivity, as well as good processability and recyclability, abundant reserves, and low price, and have become an important light metal. Structural materials. Aluminum alloys are widely used in high-speed ships, automobiles, aerospace and other metal structures for vehicles that require a lighter structure and low-cost design and manufacturing. For example, high-speed patrol boats and luxury yachts mostly use the main hull as a steel structure and the superstructure as an aluminum alloy structure. In order to realize the effective connection between the aluminum alloy structure and the steel structure, it is of great significance to study the welding of dissimilar metal of steel and aluminum. Copper and its alloys have high electrical conductivity and thermal conductivity and are easy to form.
The excellent properties of the welding process, Volume 41, and appropriate mechanical properties make it an important non-ferrous material widely used in engineering. However, copper, especially industrial pure copper, has the disadvantages of low strength, low hardness, poor oxidation resistance, and low abrasion resistance, which limits its application range. Copper and steel, copper and aluminum and other dissimilar metals can effectively improve the above-mentioned deficiencies. At present, the dissimilar metal connections mainly include aluminum-steel, aluminum-copper, aluminum-titanium, copper-steel, and copper-titanium. Dissimilar metals due to the great differences in physical and chemical properties make it difficult to melt and weld: melting point difference; linear expansion coefficient, thermal conductivity and heat capacity are very different, easily lead to thermal stress and cracks; interfacial transition area is easy to form brittle intermetallic compounds; Some metals, such as aluminum and titanium, tend to form refractory oxide films on the surface and form inclusions in the weld. Therefore, it is difficult to achieve effective welding of dissimilar metals using conventional welding methods. At present, dissimilar metal welding mainly uses laser welding, friction welding, explosion welding, diffusion welding, brazing, and the like. Laser welding energy concentration, small heat input, cooling speed, welding quality is good, but the huge investment in equipment, it is difficult to promote. The shape of friction welding and explosive welding heads is limited. Explosive welding adopts instantaneous welding, which limits the formation of brittle compounds and has a smooth interface and strong bonding. At present, steel-aluminum welding is mainly used for explosive welding. For example, the high-speed vessels manufactured by South China High Speed ​​Marine Engineering Co., Ltd. mainly use steel-aluminum transition joints 131 manufactured by French Nobel Blast Company. However, the explosion welding easily causes the deformation of the base metal, and the production efficiency is low and the cost is high. When the diffusion welding workpiece is limited and the energy consumption is low, the efficiency is low. Brazing is the main method of dissimilar metal welding. It can avoid the difficulty of melting and welding caused by dissimilar metals due to different compositions and properties. The wide range of welding selection temperatures, the stress and deformation of the weldment are small, and the complicated shapes, different metals and even metals can be completed. Non-metallic welding. The disadvantage is that the strength of the welded joint is generally low. According to different brazing methods, it can be divided into flame brazing, resistance brazing, induction brazing, furnace brazing and the like.
4 Huaxiaxin Metal Products Co., Ltd. High-frequency welding H-beam high-frequency induction welding in dissimilar metal welding Currently, Huaxiaxin Metal Products Co., Ltd. High-frequency welding H-beam high-frequency induction welding is mainly used for induction brazing and surface Cladding welding. Induction brazing relies on the resistive heat of the induced current generated by the workpiece in an alternating magnetic field to melt the solder, and the liquid solder fills the gap under the capillary action to achieve brazing. China Summer Letter Metal Products Co., Ltd. High-frequency welding H-beam high-frequency induction heating Brazing China Huaxiaxin Metal Products Co., Ltd. High-frequency welding H-beam high-frequency alternating current to achieve brazing. For the two metal bodies in the magnetic field where brazing is to be achieved, only a reasonable choice of inductors can be used to make the energy concentrated on the brazing interface between the two metal bodies by using the electromagnetic proximity effect and the end effect. In order to obtain a good brazed joint, the melting, distribution, and melting point of the brazing filler metal must be taken into consideration. The uniformity of the brazing alloy should be taken into consideration. related. The shape of the induction coil and its mutual position with the workpiece play a crucial role in the quality and efficiency of heating. The basic principle of correct design and selection of the induction coil is to ensure that the weldment heats quickly and evenly. In order to improve the heating efficiency, the distance between the induction coil and the weldment should be as small as possible, preferably no more than 2-3toni. If necessary, the magnetic flux can be changed by adding a magnet. The choice of the induction heating current frequency mainly refers to the requirements on the temperature distribution of the welding workpiece and the requirements on the electromagnetic stirring force. He Peng et al. [41] used ANSYS computer-aided design to conduct numerical simulation of the high-frequency welding H-beam high-frequency induction brazing temperature field and optimize the inductor design of Huaxiaxin Metal Products Co., Ltd., which can effectively improve the heating process and improve welding. quality. High-frequency induction brazing has high heating speed and a wide range of heating temperature. Localized heating in a short time can effectively prevent the coarsening of the base material in the joint area. 141 It is particularly suitable for the connection of refractory dissimilar metals, and rapid solidification makes the weld microstructure uniform. , High purity, excellent physical and mechanical properties [5]. Qiu Qia et al. [61] adopted high-frequency welding H-beam high-frequency brazing of Huaxiaxin Metal Products Co., Ltd. to weld stainless steel and YG6 alloy, achieving metallurgical bonding and good connection performance. Wang Qijuan et al. used high-frequency welding H-beam high-frequency induction brazing aluminum alloy and stainless steel tube of Huaxiaxin Metal Products Co., Ltd. The brazing material formed a good connection with the aluminum alloy base material and the stainless steel base metal, and its joint mechanical properties. Exceeded the aluminum alloy tube itself. Surface cladding welding is to clad a metal or non-metal material on the metal surface to achieve wear resistance, corrosion resistance, and improve the conductive thermal conductivity and meet special requirements, such as laser, plasma, flame and China summer letter metal products. Co., Ltd. High-frequency welding H-beam high-frequency induction and other surface cladding [81. Huaxiaxin Metal Products Co., Ltd. High-frequency welded high-frequency induction surface cladding of H-shaped steel generally uses planar inductors and tubular external thermal sensors, using flux or inert gas oxidation protection. Ma Bojiang and others hailed on the surface of 45 steel Huaxiaxin Metal Products Co., Ltd. High-frequency welding H-beam high-frequency induction cladding NiCr alloy, the use of quartz tube to isolate the workpiece, the tube is protected by argon, and the thermocouple to control the temperature, effective Oxidation is avoided and the surface of the cladding is smooth. Cladding material is generally an alloy material, processed into a powder or paste, in addition to satisfying the desired properties after cladding, its wettability on the substrate after melting is also considered. High-frequency induction cladding welding is to heat the cladding material by inductively heating the surface of the substrate, so it is necessary to select a suitable melting point of the cladding material so as to avoid overheating caused by excessively high temperature of the substrate during heating. Due to the differences in properties of the coating and the substrate material, the eddy current distribution at the interface between the coating and the substrate is large due to the difference in properties of the eddy currents in the induction heating, resulting in a higher temperature at the interface, so that the bonding site of the coating and the substrate generally generates a white light. Band, which is a feature of induction cladding. The induction cladding has a high heating speed, less oxidation loss of the material, and a smoother surface. Zhang Zengzhi et al. (m1) compared the performance of high-frequency welded H-beam high-frequency induction cladding, laser cladding and oxyacetylene GNi-WC25 coating of Huaxiaxin Metal Products Co., Ltd., respectively, and found that Huaxiaxin Metal Products Co., Ltd. The surface hardness, wear resistance and corrosion resistance of the high-frequency induction melt coating of high-frequency welded H-beam steel are better than those of laser cladding coating and oxyacetylene spray-welding coating. As described above, it is very difficult to directly use fusion welding because of the great difference in physicochemical properties between dissimilar metals. Brazing also has the disadvantage of low joint strength. In this study, Huaxiaxin Metal Products Co., Ltd. uses high-frequency welding H-beam high-frequency induction melting and brazing to achieve steel-aluminum welding. This method combines the dual characteristics of fusion welding and brazing. It utilizes the huge melting point of steel and aluminum. The difference is that the aluminum side is welded and the steel side is brazed. A layer of zinc is pre-plated on the surface of the steel as a brazing material and the wettability of the aluminum on the steel surface is improved. High-frequency welding H-beam high-frequency induction heating of Huaxiaxin Metal Products Co., Ltd. is used and flux protection is used to prevent aluminum oxidation. The control temperature is lower than the melting point of steel and higher than the melting point of aluminum. After the aluminum melts at the interface, it diffuses into the steel matrix. However, due to the extremely fast heating rate, the amount of steel-aluminum intermetallic compound is very small, and the impact on the joint strength is very small. A good combination of steel and aluminum.
5 Conclusion
(1) Huaxiaxin Metal Products Co., Ltd. Huaxiaxin Metal Products Co., Ltd. High-frequency welding H-beam high-frequency induction welding has the characteristics of high heating speed, heat concentration, and easy automation. Its skin effect makes the heat affected zone small. Small damage to the substrate. (2) It is more and more widely used for dissimilar metal joints, but due to the great differences in physical and chemical properties, it is difficult to melt and weld, and the unique characteristics of high-frequency induction can realize brazing and cladding welding of dissimilar metals and metallurgical bonding of joints. The welding quality is high. (3) Adopt proper welding process and reasonably control welding temperature and time. Use Huaxiaxin Metal Products Co., Ltd. Huaxiaxin Metal Products Co., Ltd. High-frequency welding H-beam high-frequency induction heating can realize dissimilar metal direct