1, carbon (C): increased carbon content in steel, the yield point and the tensile strength increased, but reduced ductility and impact resistance, when the carbon content exceeds 0.23%, weldability deteriorates, and therefore for welding Low alloy structural steel, carbon content of not more than 0.20%. But it also reduces the amount of high-carbon steel resistant to atmospheric corrosion, high carbon steel in the open-air yard would easily corroded; in addition, carbon can be increased sensitivity to cold brittleness and aging steel.
2, silicon (Si): Si added as a reducing agent in the steel making process and deoxidizer, it killed steel containing 0.15-0.30% silicon. If the steel is more than 0.50-0.60% silicon, silicon even if alloying elements. Silicon can significantly improve the elastic limit of the steel, the yield point and tensile strength, it is widely used as a spring steel. Added 1.0-1.2% silicon structure in quenched and tempered steel, strength can be increased by 15-20%. Silicon and molybdenum, tungsten, chromium, combined with improving corrosion resistance and antioxidant effects, can produce heat-resistant steel. Silicon 1-4% of low-carbon steel, with a high permeability, do silicon steel for electrical industry. Increase the amount of silicon will reduce weldability.
3, manganese (Mn): in steelmaking process, manganese is a good deoxidizer and desulfurizer, generally 0.30-0.50% manganese steel. In carbon steel added 0.70% or even "manganese", than the average amount of steel steel not only has enough toughness, and has high strength and hardness, improved hardenability of steel to improve the hot workability of steel, 40% higher than the A3 as 16Mn steel yield points. 11-14% manganese steels have high wear resistance, for the excavator bucket, ball mill liners and the like. Manganese content increased, reduced corrosion resistance of the steel, reduce welding performance.
4, phosphorus (P): In general, phosphorus is harmful elements in steel, increased cold brittleness of steel, welding performance deterioration, reduced ductility, so cold bending performance deterioration. Therefore typically require phosphorus content in steel is less than 0.045%, high-quality steel requires lower.
5, sulfur (S): sulfur is usually harmful elements. Hot brittleness of the steel produced, reducing the ductility and toughness of the steel, causing cracks in the forging and rolling. Sulfur is also detrimental to the welding performance and reduce corrosion resistance. So often it requires a sulfur content of less than 0.055%, 0.040% or less than the requirements of high-quality steel. Join 0.08-0.20% sulfur in the steel can be improved machinability, commonly referred to cutting steel.
6, chromium (Cr): the structural steel and tool steel, chromium can significantly improve the strength, hardness and wear resistance, but at the same time reducing the ductility and toughness. Chrome steel can improve the oxidation resistance and corrosion resistance, so it is stainless steel, heat-resistant steel alloying elements important.
7, nickel (Ni): Ni can improve the strength of steel, while maintaining good ductility and toughness. Nickel acid have a higher corrosion resistance, high temperature and heat capacity of rust. But because the nickel is relatively scarce resources, it should be possible to use other alternative alloying elements nickel-chromium steel.
8, molybdenum (Mo): Molybdenum makes grain refinement of steel to improve hardenability and thermal performance, maintain sufficient strength at high temperatures and creep resistance (long subjected to stress at high temperature, deformation, said creep). Adding molybdenum steel, can improve the mechanical properties.
It can also suppress the brittle steel due to the fire caused. In tool steel can improve red sex.
