The Different Types of Arc Welding
There is a common misconception from people who are not welders. That misconception is that all a welder has to do is grab the welding gun and pull the trigger. Many beginning welders are surprised when they start training that there is so much more to the trade than that. They are also surprised that there are so many different kinds of welding. For beginners, let’s go over the various kinds of welding that exist so that no one is caught by surprise when they start their training and discover they have much more to learn than they thought.
Arc welding is one of the most common kinds of welding. The concentrated heat of an electric arc joins metal by fusing the parent metal to a joint using a consumable electrode. Direct or alternating current could be used, and which one depends on the welding material and the electrode. There are different forms of arc welding, such as MIG or stick welding.
Flux-cored arc welding (FCAW) uses tubular electrodes that are filled with flux. It’s much less brittle than the coatings on SMAW electrodes and preserves most of the alloying benefits. The emissive fluxes shield the welding arc from the air, or shielding gases might be used if nonemissive fluxes are required. It’s popular when welding heavy sections an inch or more thick thanks to the higher weld-metal deposition rate.
Gas metal arc welding (GMAW), also known as MIG welding, shields the welding arc with a gas such as argon or helium or even a mixture. Deoxidizers in the electrodes can prevent oxidation which makes it possible to weld mulitple layers. It’s a simple, versatile, and economical welding process. The temperatures are also relatively low and it is used for thin sheet and sections. It can easily be automated.
Gas tungsten arc welding (GTAW) is also known as TIG welding. It uses tungsten electrodes as one pole of the arc in order to create the required heat. The gas is argon, helium, or a mixture of those two. Filler wires provide the molten material if it is necessary. This process is good for thin materials and the filler wires are similar in composition to whatever is being welded.
Plasma arc welding (PAW) has ionized gases and electrodes that generate hot plasma jets that are aimed at the welding area. These jets are extremely hot. The concentration of higher energy is good for narrower and deeper welds as well as an increase in welding speeds.
Shielded metal arc welding (SMAW) is one of the simplest, oldest, and most versatile welding methods. The arc comes from a coated electrode tip being touched to the workpiece and then withdrawn to maintain the arc. The heat that is generated melts the tip, coating, and base metal and the weld is formed out of that alloy when it solidifies. Slag that is formed and protects the weld from oxides, inclusions, and nitrides has to be removed after every pass. This is commonly used in pipeline work, shipbuilding, and construction.
Submerged arc welding (SAW) has a granular flux that is fed into the weld zone that forms a thick layer, completely covering the molten zone and preventing sparks and spatter. It allows for deeper heat penetration since it acts like a thermal insulator. The process is limited to horizontal welds and used for high speed sheet or plate steel welding. It can be semiautomatic or automatic. The flux can be recovered and treated then used again. This method provides 4-10 times as much productivity as shielded metal arc welding.
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