Arc welding is the most widely used welding method.It includes: Manual arc welding, submerged arc welding, tungsten gas shielded arc welding, plasma arc welding, melting gas welding, etc.Most arc welding is a heat source between electrode and workpiece.When forming a joint, you can use or not use filler metal.The electrode used is a melting electrode during the welding process, which is called the melting electrode arc welding, such as manual arc welding, submerged arc welding, gas shielded arc welding, tubular electrode arc welding, etc.The electrodes used are not molten carbon bars or tungsten bars during the welding process. They are called non-melting polar arc welding, such as tungsten electrode argon arc welding, plasma arc welding, etc
(1）Manual arc welding
Manual arc welding is one of the most widely used welding methods in various arc welding methods.It is the electrode and filler metal coated with paint, and the arc is burned between the end of the electrode and the surface of the welder.The coating can produce the gas to protect the arc on the one hand, while the other hand can produce the slag to cover 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 physical chemical reaction or addition of alloy element to melt gold, improve weld metal performance.Hand arc welding equipment is simple, light and flexible.It can be used for the welding of short joints in maintenance and assembly, especially for hard-to-reach parts.The welding electrode of manual arc welding can be used for most industrial carbon steel, stainless steel, cast iron, copper, aluminum, nickel and alloy.
（2）Submerged arc welding
Submerged arc welding is used as electrode and filler metal in continuous delivery.When welding, a layer of granular flux is covered in the welding area, and the arc is burned under the flux layer, melting the end of the electrode and the local parent material to form the weld.Under the action of arc heat, the upper part flux melts the slag and reacts with the liquid metal.The slag floats on the surface of the molten metal pool. On the one hand, it can protect the weld metal, prevent air pollution, and produce physical and chemical reaction with molten metal to improve the composition and performance of weld metal.On the other hand, the weld metal can be slowly cold.Large welding current can be used for submerged arc welding.Compared with hand arc welding, its biggest advantage is that the weld quality is good and the welding speed is high.Therefore, it is especially suitable for the seam of the straight seam of large workpieces.And most of them are mechanically welded.Submerged arc welding is widely used in welding of carbon steel, low alloy structural steel and stainless steel.Because slag can lower the cooling speed of the joint, some high strength structural steel, high carbon steel and other can also adopt submerged arc welding.
（3）Tungsten gas shielded arc welding
This is a kind of arc welding that does not melt the polar gas. It is used to melt the metal and form the weld with the electric arc between the tungsten electrode and the workpiece.Tungsten is extremely insolated during welding, and only the electrode is used.It is also protected by the argon or helium gas from the torch's nozzle.Additional metals may be added as needed.It is referred to as TIG welding internationally.The tungsten gas shielded arc welding is a great way to connect sheet metal and bottom welding because it controls the heat input well.This method can be used for almost all metal connections, especially for metals such as aluminum and magnesium that can form refractory oxides and reactive metals such as titanium and zirconium.The weld quality of this welding method is high, but compared with other electric arc welding, its welding speed is slower.
（4）Plasma arc welding
Plasma arc welding is also a non-melting electrode arc welding.It is to use electrode and workpiece to compress arc (call forward transfer arc) to realize welding.The electrodes used are usually tungsten.Plasma gas generated by plasma arc can be used for argon, nitrogen, helium or mixture of both.The nozzle is also protected by inert gas.The welding can be added to the metal or not to fill the metal.The welding of plasma arc welding, due to its straight arc and high energy density, the arc penetration ability is strong.The small hole effect generated by welding of plasma arc welding, and for most metals in a certain thickness range, it can not open groove butt joint, and can guarantee the uniformity of penetration and weld.Therefore, plasma arc welding has high productivity and high weld quality.However, the plasma arc welding equipment (including the nozzle) is more complicated, and the welding process parameters have higher control requirements.Tungsten gas shielded arc welding most of the metal can be soldered by the plasma arc welding.In contrast, the welding of extremely thin metal under 1mm is easy to use with plasma arc welding.
（5）Welding electrode gas shielded arc welding
This welding method is used to weld the arc of the gas that is emitted by the welding torch nozzle.The protective gases usually used to protect the arc welding are argon, helium, CO2, or the mixture of these gases.In the case of argon or helium gas, it is called the protective arc welding of melting polar inert gas (known as MIG welding);With inert gas and oxygen gas mixture to protect gas (O2, CO2), or by CO2 or the CO2 + O2 mixture to protect the air, or CO2 or the CO2 + O2 mixture as shielding gas, collectively known as the melting pole active gas shielded arc welding body (referred to as MAG welding in the world).The main advantage of the welding electrode is that it can be easily soldered in various positions, and also has high welding speed and high melting rate.The welding electrode is suitable for most major metals including carbon steel and alloy steel.The welding is suitable for stainless steel, aluminum, magnesium, copper, titanium, zirconium and nickel alloys.This welding method can also be used for arc spot welding.
（6）Tube wire arc welding
The tubular electrode arc welding is also used to weld the flame between the welding wire and the workpiece, which can be considered as a type of welding electrode.The wire used is tubular wire, which contains the flux of various components.When welding, plus protective gas, mainly CO.The welding agent is decomposed or melted, and the slag is used to protect the molten pool, the alloy and the arc.In addition to the advantages of welding electrode, the tube welding electrode has advantages in metallurgy.The tube wire arc welding can be applied to the welding of most black metal joints.Tubular wire arc welding has been widely used in some advanced industrial countries.