We will see the existence of the welding process in life and work. Where fasteners cannot be used, our first reaction is to use welding to join. There are many types of welding and sometimes it is not clear which one to use. Appropriately, today I will introduce you to the most common welding methods?
1. Arc welding with an electrode
Welding Arc welding is a method of arc welding in which the welding electrodes are manually operated, so the quality of welding depends on the operator's work technology, which requires higher work qualifications from welders. Electrode arc welding is one of the most widely used types of fusion welding. It and gas shielded welding are called the two pillars of fusion welding, accounting for more than 80% of fusion welding.
Its principle: the welding arc is provided by a welding current source, and in a gaseous environment between two electrodes with a certain voltage or between the electrodes and the workpiece to be welded, a strong and prolonged discharge phenomenon is created. When one end of the electrode comes into contact with the workpiece, it causes an instantaneous short circuit and creates a high temperature that quickly melts the contact metal and releases metal fumes. That's why we usually see welders with a welding machine and a pack of welding electrodes.
2. Argon-arc welding
Argon arc welding is a welding technology that uses argon as the shielding gas. This technology is also known as argon gas welding. That is, around arc welding, argon is used as a shielding gas, which isolates the air from the welding zone and prevents oxidation of the welding zone. Compared with manual welding, the arc and molten pool are visible, the operation is convenient, and thin active metal sheet structure can be welded; the welding quality is good, the joint strength can reach 80-90% of the base metal. , and there is no spatter during welding. The stress, deformation, and cracking tendency of welded parts are small, and the welding guard is the most common in life.
3. Gas welding
Gas welding, in English: oxygen gas welding (abbreviated as OFW). Welding method in which the flame produced by the mixed combustion of a combustible gas and a combustion gas is used as a heat source to melt it. The combustion gas is mainly oxygen, and the combustible gas is mainly acetylene, liquefied petroleum gas, etc. This kind of welding does not require electricity, and mainly uses gas cylinders and welding tools. Because it is a pressurized gas storage cylinder , the welding process is also very dangerous. The main advantages of this welding are that it can be used without a power source. and effective for welding cast iron and some non-ferrous metals. Good workability, the disadvantage is that the welding efficiency is low, the deformation after welding is large, and it is difficult to realize automation.
4. Laser welding
Laser welding is an efficient and precise welding method that uses a high energy density laser beam as a heat source.
Laser welding is non-contact welding. The welding process does not require pressure testing, but requires an inert gas to prevent oxidation of the molten pool, and sometimes a filler metal is used. Its main advantages are high speed, large depth and low deformation, the disadvantage is high requirements for location, the need to equip with devices for welding, and the high cost of equipment.
5. Friction welding
Friction welding refers to a welding method using the heat generated by rubbing the contact surface of a workpiece as a heat source, causing the workpiece to plastically deform under pressure.
The principle is as follows: friction destroys the protective film on the metal surface and generates heat, which reduces the strength of the metal and increases its plasticity. The metal on the friction surface produces plastic deformation and flow, and prevents metal oxidation. , and contributes to metal welding Mutual diffusion of atoms forms a strong weld.
Advantages: good and stable welding quality of joints, suitability for welding dissimilar steels and dissimilar metals, high dimensional accuracy of welded joints, no sparks and harmful gases will be generated in the process.
Disadvantages: Rely on rotating welding, and difficult to weld non-circular sections
6. Soldering
Brazing is a method of joining by heating to a soldering temperature below the melting point of the base metal, but above the melting point of the solder, using solder whose melting point does not exceed 450°C (as defined by the American Welding Society). The solder spreads over tightly fitting butt surfaces by capillary action or spreads over the surface of the workpiece by wetting.
Soldering is basically based on wetting the solder with the base metal to form a joint. The advantages are ease of operation, low heating temperature and ease of automation.
7. Submerged Arc WeldingSubmerged arc welding (including submerged arc welding, electroslag welding, etc.) is a welding method in which the arc burns under a layer of flux. Submerged arc welding is one of the mechanized welding methods with high production efficiency today. It has the advantages of high production efficiency, good welding quality and good working environment. It is widely used in the production of important steel structures, such as pressure vessels, pipe sections and box beams.