Arc welding of carbon dioxide gas protection

1, carbon dioxide gas shielded arc welding (CO2 welding) is carbon dioxide (sometimes used CO2+O2 mixed gas).

Due to the special effect of the 0 thermal physical properties of carbon dioxide gas, when the conventional welding power is used, the molten metal at the end of the wire is not likely to form a balanced and free axial transition. It usually needs short circuit and droplet necking, so it is more spatter than the free transition of MIG welding. However, if a high quality welder is used and the parameters are chosen properly, a stable welding process can be obtained, so that the splash is reduced to a minimum.

Because of the low price of the protective gas used, the welding seam is good when the short circuit transition is used, and the welding wire with deoxidizer can be used to obtain the welding joint without internal defects. Therefore, this welding method has become one of the most important welding methods for ferrous metal materials.

2. The welding rod is composed of two parts of the welding core and the medicine skin.

The electrode is evenly coated on the welding core outside the metal core. The type of electrode is different, and the core is different. In order to ensure the quality and performance of the weld, the content of metal elements in the welding core is strictly regulated, especially for the harmful impurities (such as sulfur, phosphorus, etc.), which should be strictly limited and superior to the parent material. The composition of the welding core directly affects the composition and performance of the weld metal, so the harmful elements in the welding core should be as few as possible.

The welding core of welding carbon steel and low alloy steel is generally used as the core of low carbon steel and filled with manganese, silicon, chromium and nickel (see the national standard of welding wire GB1300 77). The reason for low carbon use is that the steel wire is plastic with low carbon content, and the wire drawing is easy. On the other hand, it can reduce the CO content of the reducing gas, reduce the spatter or air hole, and increase the temperature of the weld metal solidification, which is beneficial to the invert welding. The addition of other alloying elements is mainly to ensure the comprehensive mechanical properties of the weld, and also to the welding process performance and removal of impurities.

High alloy steel and other metal materials such as aluminum, copper, cast iron, and other metal materials, in addition to the welding core components in addition to the weld metal near the outside, also to control the content of impurities, and often added to certain specific alloy elements according to the process requirements. A welding rod is a melting electrode used for arc welding of covered electrodes. It consists of two parts: the skin and the core. The chamfer on the front of the electrode is about 45 degrees, which is convenient for starting arc. There is a bare core in the rear part, which accounts for about 1/16 of the total length of the electrode, which is convenient for holding the clamp and conductive. The diameter of the electrode, which refers to the diameter of the welding core, is usually 2, 2.5, 3.2 or 3, 4, 5 or 6mm, commonly used as small 3.2, 4, and 5 three, and the length "L" is generally between the 250^-450 mm.