These welding methods belong to different degrees of specialization of welding methods, and their application scope is narrow.It mainly includes electric slag welding and high frequency welding with resistance heat as energy.Gas welding, gas pressure welding and explosive welding for welding energy.It can be used for welding, welding, ultrasonic welding and diffusion welding.
(1) the electroslag welding
As mentioned above, electroslag welding is the welding method of energy for the resistance of slag.The welding process is carried out in the vertical welding position, in the gap between the two workpiece ends and the two water-cooled copper sliding blocks.The end of the workpiece is melted by the resistance heat generated by the current through the slag.According to the electrode shape used in welding, electroslag welding is divided into wire slag welding, plate electroslag welding and welding nozzle electroslag welding.The advantage of electroslag welding is that the workpiece can be welded with a large thickness (from 30mm to over 1000mm) with high productivity.It is mainly used for welding joint and t-joint of cross section.Electroslag welding can be used for welding of various steel structures and for the welding of castings.The welding head of electroslag is slow due to heating and cooling. The thermal influence area is wide and the microstructure is large and strong. Therefore, it is necessary to carry out normal fire treatment after welding.
(2) the high frequency welding
High frequency welding is the energy of solid resistance heat.When welding the resistance of the heat generated by high frequency current within the workpiece heated to melt the surface layers of workpiece welding area or close to the plastic state, then apply (or not applied) upset forging force and realize the combination of metals.Therefore, it is a solid-phase resistance welding method.High frequency welding can be divided into high frequency welding and induction high frequency welding according to high frequency current in the workpiece.When contact with high frequency welding, high frequency current is passed into the workpiece by contact with the workpiece.The induction current is generated in the workpiece by the coupling of the external induction loop of the workpiece.High frequency welding is a highly specialized welding method, which should be equipped with special equipment.High productivity and welding speed of 30m/min.It is mainly used to weld the longitudinal seam or spiral seam of the tube.
(3) gas welding
Gas welding is a kind of welding method with gas flame as heat source.The most widely used oxygen-acetylene flame is made of acetylene gas.Because of the simple operation of the equipment, the heating speed and the low productivity of the gas welding, the thermal influence area is larger, and can easily cause larger deformation.Soldering can be used for welding of many ferrous metals, nonferrous metals and alloys.Generally suitable for repair and single piece sheet welding.
(4) the air pressure welding
Like gas welding, air pressure welding is also a heat source with gas flame.When welding, heat the end of the two butt parts to a certain temperature, then apply enough pressure to get a strong connection.It is a solid phase welding.Air pressure welding without filler metal, often used in railway welding and reinforcement welding.
(5) the explosion welding
Explosive welding is another method of solid - phase welding with chemical reaction heat as energy.But it USES the energy generated by the explosive explosion to connect the metal.In the event of an explosion wave, two pieces of metal can be accelerated to form a metal bond in less than a second.In all kinds of welding methods, explosive welding can be soldered in the widest range of different metals.There are two kinds of transition joints that can be welded with two metals which are not compatible with metallurgical welding.It is an efficient way to make composite plate by using a large amount of sheet cover.
(6) the friction welding
Friction welding is the solid phase welding of mechanical energy.It USES the heat generated by mechanical friction between the two surfaces to connect the metal.The heat concentration of friction welding is concentrated at the joint surface, so the thermal influence area is narrow.Pressure is applied between the two surfaces, most of which increase the pressure when the heat is terminated, and the hot metal is subjected to the top forging and the union surface does not melt.Friction welding is high in productivity, and almost all metals that can be heated can be welded together.Friction welding can also be used for welding of heterogeneous metals.A workpiece with a maximum diameter of 100mm is suitable for cross-section.
(7) ultrasonic welding
Ultrasonic welding is also a kind of solid - phase welding method for energy.In the case of ultrasonic welding, the welds are made by the high frequency vibration of the acoustic pole under the lower static pressure, which causes the joint surface to produce a strong splitting friction and heating to the welding temperature.Ultrasonic welding can be used for welding of most metal materials. It can weld metal, foreign metal and metal and non - metal.It can be used for the repeated production of thin plate metal joints with wire, foil or 2~ 3mm.(8) diffusion weld diffusion welding is generally used as a solid-phase welding method for indirect heat energy.Usually in a vacuum or a protective atmosphere.In welding, the surfaces of the two welders are exposed to high temperature and high pressure for a certain time to reach the interatomic distance, which is combined with the simple mutual diffusion of atoms.Not only need to clean the surface of the workpiece surface of the impurities before welding, but the surface roughness is less than a certain value to ensure the welding quality.Diffusion welding has little deleterious effect on the properties of the welded material.It can weld many of the same and heterogeneous metals as well as some non-metallic materials such as ceramics.Diffusion welding can weld complex structures and different thickness.