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Carbon dioxide gas shielded arc welding
1. Carbon dioxide gas shielded arc welding (referred to as CO2 welding) protection gas is carbon dioxide (sometimes using CO2+O2 mixture).
Due to the special effect of 0 thermal physical properties of carbon dioxide gas, the use of conventional welding power source, wire end of molten metal may not form axial free transition equilibrium, we usually need the droplet short-circuit and necking rupture, therefore, compared with MIG welding spatter free transition, more. But if a high quality welding machine is adopted and the parameters are chosen properly, a stable welding process can be obtained so as to minimize the spatter.
Because the protective gas is low in price, the weld is well formed when short circuiting is used, and the quality of the welded joint is free of internal defects with the use of a wire containing deoxidizer. Therefore, this welding method has become one of the most important welding methods for ferrous metal materials.
2. The electrode is composed of two cores and coating composition.
The electrode is coating in metal welding core (coating), uniform centripetal pressure applied to core. The electrode of different types, different cores. The core metal cored electrode, in order to ensure the quality and performance of the weld, there are strict rules on the contents of metal elements in the core, especially for harmful impurities (such as sulfur, phosphorus content, etc.) should be strictly restricted, better than the base metal. The core components directly affect the composition and properties of the weld metal, so the harmful elements in the welding core to as little as possible.
For welding of carbon steel and low alloy steel welding core, are mostly made of low carbon steel as the core, and adding manganese, silicon, chromium, nickel and other components (see wire national standard GB1300 - 77). The reason of low carbon is a low carbon steel wire plastic, wire drawing is relatively easy, on the other hand can reduce the CO content of reducing gas, reduce spatter or porosity and increased weld metal solidification temperature, favorable for overhead welding. The addition of other alloy elements mainly guarantees the comprehensive mechanical properties of the weld, and also has some effect on the welding process performance and the removal of impurities.
Other metal materials of high alloy steel and aluminum, copper, iron, its core components in addition to the requirements of the weld metal are similar, and also to control the content of impurities, and often adding certain alloying elements according to the process. Melting electrode arc welding for the electrode is coated with a coating, which is composed of coating and cores is composed of two parts. At the end of the electrode, the leather has a chamfer of about 45 degrees, which is convenient for starting the arc. There is a bare core in the tail, about the electrode length of 1/16, to facilitate the welding clamp hold and conductive. The electrode diameter of secondary core diameter) actually refers to is usually 2, 2.5, 3.2 or 3, 4, 5 or 6mm of several specifications, commonly used is 3.2 small, 4 small, 5 small three, the length of "L" in 250^-450 mm.