Common iron welding process metal welding
- Jan 03, 2019 -

1. Arc welding


Arc welding is currently the most widely used welding method. It includes: hand arc welding, submerged arc welding, tungsten gas shielded arc welding, plasma arc welding, and gas metal arc welding. Most arc welding is based on the arc of combustion between the electrode and the workpiece. When forming the joint, the filler metal may or may not be used. When the electrode used is a wire that is melted during the welding process, it is called a melting arc welding, such as hand arc welding, submerged arc welding, gas shielded arc welding, tubular wire arc welding, etc.; the electrode used is not melted during the welding process. When a carbon rod or a tungsten rod is used, it is called non-melting arc welding, such as tungsten argon arc welding, plasma arc welding, and so on.


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2. Hand arc welding


Hand arc welding is one of the earliest and most widely used welding methods in various arc welding methods. It is an electrode coated with an external coating electrode and a filler metal. The arc is burned between the end of the electrode and the surface of the workpiece being welded. On the one hand, the coating can generate gas to protect the arc under the action of arc heat, and on the other hand, it can produce slag covering the surface of the molten pool to prevent the interaction of the molten metal with the surrounding gas. The more important role of slag is to produce a physicochemical reaction with molten metal or to add alloying elements to improve weld metal properties. The hand arc welding equipment is simple, light and flexible. It can be applied to the welding of short seams in maintenance and assembly, especially for welding in hard-to-reach areas. Hand arc welding with the corresponding electrode can be applied to most industrial carbon steel, stainless steel, cast iron, copper aluminum, nickel and their alloys.


3. Submerged arc welding


Submerged arc welding is a wire that is continuously fed as an electrode and a filler metal. During welding, a layer of granular flux is applied over the weld zone, and the arc burns under the flux layer to melt the end of the wire and the local base material to form a weld. Under the action of arc heat, the upper part of the flux melts the slag and undergoes a metallurgical reaction with the liquid metal. The slag floats on the surface of the molten metal pool, which can protect the weld metal, prevent air pollution, and produce physical and chemical reactions with the molten metal to improve the weld metal and performance. On the other hand, the weld metal can be made. Slowly licking. Submerged arc welding can use a larger welding current. Compared with hand arc welding, its biggest advantage is the good weld quality and high welding speed. Therefore, it is particularly suitable for welding straight seams of large workpieces. And most use mechanized welding. Submerged arc welding has been widely used in the welding of carbon steel, low alloy structural steel and stainless steel. Since slag can reduce the joint cooling rate, some high-strength structural steels, high-carbon steels, etc. can also be submerged arc welded.


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4. Tungsten gas shielded arc welding


This is a non-melting gas shielded arc welding that utilizes an arc between the tungsten electrode and the workpiece to melt the metal to form a weld. During the welding process, the tungsten does not melt and acts only as an electrode. At the same time, argon or helium is fed from the nozzle of the torch for protection. Additional metals can be added as needed. Internationally known as TIG welding. Tungsten gas protection arc soldering is an excellent way to connect thin metal and primer because it provides good control of heat input. This method can be used for almost all metal connections, especially for welding aluminum, magnesium, metals that form refractory oxides, and reactive metals such as titanium and zirconium. This welding method has a high weld quality, but its welding speed is slower than other arc welding.


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5. Plasma arc welding


Plasma arc welding is also an infusible pole arc welding. It uses a compression arc between the electrode and the workpiece (called a forward transfer arc) to achieve welding. The electrodes used are usually tungsten. The plasma gas that produces the plasma arc can be argon, nitrogen, helium or a mixture of both. It is also protected by an inert gas through the nozzle. Filler metal may be added during welding or without filler metal. In plasma arc welding, the arc penetration ability is strong due to the straightening of the arc and the high energy density. The small hole effect produced by plasma arc welding can be used for the non-grooving of most metals in a certain thickness range, and the penetration and weld uniformity can be ensured. Therefore, plasma arc welding has high productivity and good weld quality. However, plasma arc welding equipment (including nozzles) is relatively complicated and requires high control of welding process parameters. Most metals that can be welded by tungsten gas shielded arc welding can be plasma arc welded. In contrast, for extremely thin metal soldering of 1 mm or less, plasma arc welding can be easily performed.