Brazing of heat energy can be a chemical reaction, or indirect heat. It is the use of lower melting point than the melting point of the welded materials for low-metal brazing, heated to melt the solder, the solder materials by capillary action into the joint space within the contact surface, wetting the surface of the metal being welded, the liquid and interdiffusion between the solid phase to form brazed joints. Therefore, the brazing is a solid phase and liquid phase welding method. Brazing heating temperature is lower, the base metal does not melt, but also without pressure. But before welding must take certain measures to clear the Welding Wire surface of oil, dust, oxide film. This is a good wettability to the workpiece, an important guarantee to ensure joint quality. Solder liquidus above 450 â„ƒ and the humidity is lower than the melting point of base metal, known as the brazing; less than 450 â„ƒ, called soldering. According to the heat source or heating methods can be divided into different brazing: flame brazing, induction brazing, furnace brazing, dip brazing, resistance brazing, etc. Brazing temperature is relatively low due to heating, so the less impact the workpiece material properties, welding stress and deformation is also small pieces. However, the strength of brazed joints is generally low, heat resistance is poor. Brazing can be used for welding carbon steel, stainless steel, high temperature alloys, aluminum, copper and other metal materials, you can connect dissimilar metals, metal and nonmetal. Suitable for Tungsten Electrode or at room temperature under load is not the work of connectors for precision, miniature and complex multi-brazing seam welding is especially useful.
These welding methods are different levels of specialized welding method, its scope is narrow. Including the resistance of heat energy electroslag welding, high frequency welding; to chemical energy for welding gas welding, pressure welding, explosion welding; to mechanical energy for welding friction welding, cold welding, ultrasonic welding, diffusion bonding. (1) electroslag welding As mentioned earlier, electroslag welding slag resistance heat is the energy of the welding method. Welding process in the vertical welding position, in the face and on both sides of the workpiece by the two water-cooled copper block assembly formed within the gap. Current through the use of Welding Electrodes slag resistance heat generated will melt the workpiece end. When used according to the welding electrode shape, electroslag welding wire into a very electroslag welding, plate welding and electroslag melting polar mouth electroslag welding. Electroslag welding's advantages are: weldable workpiece thickness (from 30mm to greater than 1000mm), the production rate. Used in cross-section T-butt joints and welded joints. Electroslag welding can be used for a variety of welding steel structures can also be used for welding castings. Electroslag welding head are slow due to heating and cooling, heat-affected zone width, coarse microstructure, toughness, it is generally required to be normalized after welding process. (2) high-frequency welding Frequency resistance welding is a solid with heat energy. Welding using high-frequency current in the resistance heat generated within the workpiece so that the workpiece is heated to melt the welding zone or near the surface of the plastic state, then apply (or not applied) forging force to achieve a combination of metals. Therefore, it is a solid-phase resistance welding method. High-frequency welding current according to high-frequency heat generated in the workpiece can be divided into contact with high-frequency high-frequency welding and induction welding. Exposure to high-frequency welding, high frequency current through mechanical contact with the workpiece passing the workpiece. High frequency induction welding, high frequency current through the workpiece external induction loop coupling and induced current in the workpiece. Strong high-frequency welding is a specialized welding method, according to the product is equipped with special equipment. Production rate, welding speed up to 30m/min. When the tube is mainly used for manufacture of vertical seam or spiral seam welding. (3) welding Welding with a gas flame to heat welding method. The most widely used is acetylene gas as fuel oxygen - acetylene flame. As the equipment is simple to make easy to operate, but the heating rate and low productivity gas welding, large heat-affected zone, and easily lead to a larger deformation. Welding can be used for a lot of black metal, nonferrous metal and alloy welding. Generally applicable to a single piece of sheet metal repair and welding. (4) pressure welding Pressure welding and gas welding as pressure welding is a gas flame as the heat source. Butt welding the two ends of the workpiece is heated to a certain temperature, then put enough pressure to get a solid connection. Is a solid phase welding. Pressure welding without filler metal, welding and steel used in rail welding. (5) Explosive welding Explosive welding is the chemical reaction heat as energy alternative solid-phase welding method. But it is the use of explosives to achieve the energy generated by the metal connections. Role in the blast wave, the two pieces of metal in less than one second of time can be accelerated impact the formation of metal combination. Methods in a variety of welding, explosion welding of dissimilar metals can be welded to the widest range of combinations. Explosion welding can be used on the metallurgy of the two incompatible for a variety of transition metal welded joints. Explosion welding a large surface area used for flat-coated, is an efficient way to fabricate composite panels. (6) friction welding Friction welding is a mechanical energy of the solid phase for Mig Welding Wires. It is the use of mechanical friction between two surfaces of the heat generated to achieve the connection of the metal. Concentrated in the heat of friction welding joints, and are therefore narrow heat-affected zone. Pressure between the two surfaces to be, in most cases is increasing pressure in the heating is terminated, the hot metal by forging the integration of the joint surface is not usually melt. Friction welding productivity high, in principle, almost all can be hot-forged metal can be friction welded. Friction welding of dissimilar metals can also be used for welding. To apply to a circular cross-section of 100mm maximum diameter of the workpiece. (7) ultrasonic welding Ultrasonic welding is a kind of mechanical energy as the energy of the solid phase welding method. Ultrasonic welding, welding the workpiece at a lower static pressure, issued by the sound of very high frequency vibration can produce strong joints crack and friction welding temperature and heated to form a combination. Ultrasonic welding can be used for most of the welding between the metal, to achieve metal, dissimilar metals and welding between the metal and nonmetal. Applied to wire, foil, or 2 ~ 3mm sheet metal joints following the duplication of production. (8) diffusion bonding Diffusion bonding is generally based on indirect heat for the energy of the solid phase welding method. Usually carried out under vacuum or protective atmosphere. Welder welding the two pieces of the surface by high temperature and pressure greater contact and holding a certain time in order to achieve the distance between atoms, each spread through the simple combination of atoms. Not only need to be cleaned before welding surface oxides and other impurities, and surface roughness is lower than a certain value to ensure the welding quality. Diffusion bonding properties of the materials being welded almost no harmful effects. It can weld dissimilar metals, and many of the same species as well as some non-metallic materials such as ceramics. Diffusion welding can be welded and the thickness of the complex structure of very different parts.