Welding arc has the following advantages: l) Use of equipment is relatively simple, relatively inexpensive and lightweight. Electrode arc welding using AC and DC welding machines are relatively simple, the welding operation without complicated auxiliary equipment, just with simple tools. Therefore, the purchase of equipment investment, and easy maintenance, which is one of the reasons it is widely used. 2) does not require auxiliary gas protection. Not only to provide filler metal electrode and the welding process to produce a protective welding bath and shielding gas to prevent oxidation, and has strong wind resistance. 3) is flexible and adaptable. Arc Welding Electrode for single or small quantities of products, short and irregular, space is not easy anywhere, and other mechanized welding seam. To reach the place where the electrode can be welded. 4) Wide range, suitable for most industrial metals and alloys welding. Appropriate choice of electrode arc welding electrode can not only welded carbon steel, low alloy steel, but also high-alloy steel and nonferrous metal welding, the same can not only weld metal, and can weld dissimilar metals, can also be cast iron welding and welding and other metal materials. However, the welding arc has the following disadvantages: l) of the technically demanding welder, welder training costly. Electrode arc welding quality, except by the appropriate choice of electrodes, welding parameters and welding equipment, welding operations depends mainly on technology and experience to ensure that the welding arc welding quality to some extent determined by the welding technique. Welders must be regular training, the training costs required great. 2) poor working conditions. Welding arc welder depends mainly on manual and complete the whole process of observing eyes, welder's labor-intensive, and always in high-temperature baking and toxic smoke environment, poor working conditions, so to strengthen labor protection. 3) low productivity. Depends mainly on the electrode manual arc welding, and a smaller selection of welding parameters, in addition, welding electrodes must be frequently changed, and should always be clean weld slag, compared with the automatic welding, welding low productivity. 4) is not suitable for special sheet metal and welding. For the active metals (such as Ti, Nb, Zr, etc.) and refractory metals (such as Ta, Mo, etc.), because these metals are very sensitive to oxygen, not enough to prevent the protective effect of welding the metal oxide, the protective effect is not good enough, weld quality is not up to become, we can not use electric arc welding; for low melting point metals such as Ti, Nb, Zr and its alloys, due to electric arc in terms of its high temperature, so it can not use electric arc welding electrodes welding. Another. Electric arc welding electrode for welding the workpiece thickness of 1.5mm or more, 1mm below the sheet is not suitable for electric arc welding electrodes. As the electrode electric arc welding with simple equipment, easy operation, strong adaptability to any position in space welding characteristics, it is widely used in various industrial fields, is the most widely used welding methods.