1, carbon (C): increased carbon content in steel, yield and tensile strength increased, but the plasticity and impact reduction, when the carbon content of more than 0.23%, the steel welding performance deterioration, so for welding Low alloy structural steel, carbon content is generally not more than 0.20%. The high carbon content also reduces the atmospheric corrosion resistance of steel, and the high carbon steel in the open field is easy to rust. In addition, carbon can increase the cold brittleness and aging sensitivity of steel.

2, silicon (Si): in the steelmaking process as a reducing agent and deoxidizer, so sedative steel containing 0.15-0.30% of the silicon. If the silicon content of steel exceeds 0.50-0.60%, silicon even alloying elements. 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% of the silicon, the strength can be increased by 15-20%. Silicon and molybdenum, tungsten, chromium and other combinations, to improve the role of corrosion resistance and oxidation, can produce heat-resistant steel. Silicon-containing 1-4% of low-carbon steel, with a 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 desulfurization agent, the general steel containing 0.30-0.50% manganese. When adding 0.70% or more of carbon steel, it will not only have sufficient toughness, but also have high strength and hardness, improve the quenching of steel and improve the hot working performance of steel even if it is "manganese steel" Such as 16Mn steel than A3 yield point 40% higher. Containing 11-14% of the steel has a high wear resistance, for the excavator bucket, ball mill liner. Manganese increased, reducing the corrosion resistance of steel, reducing welding performance.