According to the nature of the electrode drug skin, the electrode can be divided into two categories of acid electrode and alkaline welding rod. Drug skin contains large amounts of acidic oxides (TiO2, SiO2, etc.) electrode is called the acid electrode. Drug skin contains large amounts of alkaline oxides (CaO, Na2O, etc.) is called the alkaline electrode. Acid electrode AC and DC welding performance is good, but the weld mechanical properties, especially the poor impact toughness, suitable for low-carbon steel and low strength low alloy steel welding is the most wide electrodes. Alkaline electrode desulfurization, dephosphorization ability dehydrogenase role of drug skin. Welded joints hydrogen content is very low, it is also known as low-hydrogen electrodes. Alkaline electrode welds with good crack resistance and mechanical properties, but poor process performance, general welding with DC power supply is mainly used for welding of important structures (such as boilers, pressure vessels and alloy structural steel, etc.). According to the use of welding rod, welding rod can be divided into structural steel electrode (carbon steel electrodes and low-alloy welding rod), stainless steel electrodes, cast iron welding, heat-resistant steel Welding Electrodes, low temperature Welding Cable, welding electrodes, copper and copper alloys, nickel and nickel alloys, aluminum and aluminum alloys, including structural steel electrode is the most widely used.