The five elements of the steel performance: 1, carbon (C): steel carbon content increased, yield point and tensile strength increased, but the plasticity and impact decreased, when the carbon content of more than 0.23%, the steel welding performance Deteriorates, the low carbon steel used for welding generally has a carbon content of not more than 0.20%. High carbon content will also reduce the atmospheric corrosion resistance of steel, high-carbon steel in the open yard susceptible to corrosion; In addition, carbon can increase the steel's cold brittleness and aging sensitivity. 2, silicon (Si): add silicon in the steelmaking process as a reductant and deoxidizer, so the killed steel contains 0.15-0.30% of silicon. If the amount of silicon in the steel exceeds 0.50-0.60%, silicon is an alloying element. Silicon can significantly improve the elastic limit of steel, yield point and tensile strength, it is widely used for spring steel. In the quenched and tempered structural steel by adding 1.0-1.2% silicon, the intensity can be increased 15-20%. Silicon and molybdenum, tungsten, chromium and other combinations, to improve the corrosion resistance and the role of antioxidant, heat-resistant steel can be made. Silicon 1-4% of the low-carbon steel, with high permeability, for the electrical industry to do silicon steel. Increasing the amount of silicon will reduce the weldability of the steel. 3, manganese (Mn): In the steelmaking process, manganese is a good deoxidizer and desulfurizer, manganese steel generally 0.30-0.50%. When adding 0.70% or more of carbon steel, even if it is "manganese steel", not only the toughness of steel is higher than that of ordinary steel, but also the higher strength and hardness, the hardenability of steel, the hot working property of steel, Such as 16Mn steel yield point higher than the A3 40%. Manganese 11-14% of the steel has a very high wear resistance, for excavators shovels, ball mill liner and so on. Manganese increased, weaken the corrosion resistance of steel, reduce the welding performance. 4, phosphorus (P): In general, phosphorus is a harmful element in steel, increasing the cold brittleness of steel, so that the deterioration of the welding performance, reduce plasticity, so that the performance of cold-formed deterioration. Therefore, it is usually required that the content of phosphorus in steel should be less than 0.045%, and the quality steel should be lower. Sulfur (S): Sulfur is also a harmful element in normal circumstances. The hot brittle steel to reduce the ductility and toughness of steel, causing cracks in the forging and rolling. Sulfur on the welding performance is also unfavorable, reducing corrosion resistance. Therefore, sulfur content is usually less than 0.055%, high-quality steel requirements of less than 0.040%. Adding 0.08-0.20% sulfur to the steel improves machinability, often called free-cutting steel.
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