Carbon (C) Carbon is the main alloying element in steel, When the carbon content increases, the strength of steel, the hardness significantly increased, while the plasticity decreases. In the welding process, the carbon play a certain role in deoxy role in the arc under high temperature and oxygen compounds, to generate carbon monoxide and carbon dioxide gas, arc and pool ambient air excluded, to prevent oxygen in the air, nitrogen harmful gas bath adverse impact of reducing the oxygen and nitrogen content in weld metal. If the carbon content is too high, severe reduction will cause a large splash and stomatal Take into account the impact of carbon steel hardenability and increase crack sensitivity, low-carbon steel welding core carbon content is generally 0.1%. Manganese (Mn) manganese steel is a good alloying agent, and its strength and toughness increased with increasing manganese content. In the welding electrode, manganese is also a good deoxidizer, can reduce the oxygen content in the weld. Manganese and sulfide co-formation of manganese sulfide float in the slag, thereby reducing the weld hot cracking tendency. General carbon structural steel welding core manganese content of 0.30% 0 55% of welding some special-purpose steel wire, the manganese content up to 1. 70% of 2.10%. Silicon (Si) Silicon is also a good alloying agent, adding an appropriate amount of silicon in steel can improve the yield strength, flexibility and acid resistance; if the content is too high, then reduce the ductility and toughness. In the welding process, the silicon also has a good deoxidation capacity with oxygen to form silicon dioxide, but it will improve the viscosity of the slag, easy to promote non-metallic inclusions generated. Chromium (Cr) Chromium can increase the hardness, wear resistance and corrosion resistance. For low-carbon steel, chromium is an accidental impurity. Metallurgical characteristics of the chromium is subject to rapid oxidation, the formation of refractory oxides of chromium oxide (Cr2O3), thereby increasing the likelihood of weld metal inclusions. Chromium oxide transition to slag make the slag viscosity increased, decreased mobility. Nickel (Ni) of nickel on the toughness of steel have more significant effects, the general low-temperature impact value higher, the appropriate incorporation of nickel. Sulfur sulfur (S) is a harmful impurities, with the increase of sulfur content, will increase the tendency of hot cracking of welds, Welding Cable sulfur content not greater than 0.04%. In the welding of important structures, the sulfur content not greater than 0.03%. Phosphorus (P)