1, carbon (C): the increase of carbon content in steel, yield point and tensile strength increased, but the plasticity and impact resistance decreased, when the carbon content of more than 0.23%, bad welding properties of the steel, so for low alloy structural steel welding, the carbon content is generally not more than 0.20%
. High carbon content will also reduce the atmospheric corrosion resistance of steel, in the open field of high carbon steel on
Corrosion; in addition, carbon can increase the cooling of steel
Brittleness and aging sensitivity.
2, silicon (Si): in the process of steelmaking with silicon as a reducing agent and deoxidizer, so calm steel contains 0.15 - 0.30% of silicon. If there is more than 0.50-0.60% silicon in the steel, silicon is alloying. Silicon can be significantly improved
It is widely used as spring steel because of its elastic limit, yield point and tensile strength. Join the 1.01.2% silicon in the quenched and tempered steel, strength can be increased by 15-20%. The combination of silicon, molybdenum, tungsten and chromium can improve the corrosion resistance and oxidation resistance, and can be used to manufacture heat-resistant steel. Low carbon steel containing silicon 1 - 4%, with a high permeability, used in electrical industry silicon steel sheet. The increase in silicon will reduce the weldability of steel.
3, manganese (Mn): in the process of steelmaking, manganese is a good deoxidizer and desulfurizer, manganese in general steel 0.30 - 0.50%. When more than 0.70% of carbon steel is added, even manganese steel is not only adequate for the steel of ordinary steel
Toughness and higher
Strength and hardness increase the hardenability of steel and improve the hot workability of steel, such as 16Mn steel, which is 40% higher than the yield point of A3. Steel containing 11 - 14% manganese is very high
Abrasion resistance, used for excavator bucket, ball mill lining board, etc.. The manganese content increases, weakens the steel corrosion resistance, reduces the welding performance. 4, phosphorus (P): in general, phosphorus is a harmful element in steel, increasing cold brittleness of steel, making welding performance worse, reducing plasticity, and making cold bending property deteriorate. Therefore, steel is usually required to contain less than 0.045% phosphorus, high quality steel requirements are lower.
5, sulfur (S): sulfur is, in general, also a harmful element. To cause hot brittleness of steel, to reduce the ductility and toughness of steel, and to cause cracks in forging and rolling. Sulfur is also detrimental to weldability and reduces corrosion resistance. Therefore, sulfur content is usually less than 0.055%, high quality steel requirements are less than 0.040%. The addition of 0.08-0.20% sulfur in steel improves machinability, often referred to as free cutting steel.
6 chromium (Cr): in structural steel and tool steel, chromium can significantly increase strength, hardness and wear resistance, but at the same time reduce plasticity and toughness. Chromium can also improve the oxidation resistance and corrosion resistance of steel, which is an important alloying element of stainless steel and heat-resistant steel. 7, nickel (Ni): nickel can improve the strength of steel, while maintaining good plasticity and toughness. Nickel has higher corrosion resistance to acid and base, and has the ability of rust prevention and heat resistance under high temperature. But because the nickel is a scarce resource, it should try to use other alloying elements substitution of nickel chromium steel.
8, molybdenum (Mo): molybdenum can make steel grain refinement, improve hardenability and thermal strength, at high temperature to maintain enough strength and creep resistance (long-term under high temperature stress, deformation, called creep). The addition of molybdenum into structural steel improves mechanical properties. It can also restrain the brittleness of alloy steel due to fire. Improve red in tool steel.
9, titanium (Ti): titanium is a strong deoxidizer in steel. It can make the inner structure of steel compact, refine grain power, reduce aging sensitivity and cold brittleness. Improve welding performance. Adding proper titanium into chromium 18 nickel 9 austenitic stainless steel can avoid intergranular corrosion. 10, vanadium (V): vanadium is a good deoxidizer of steel. 0.5% of the vanadium in the steel can refine the grain and improve the strength and toughness. The carbides formed by vanadium and carbon can improve hydrogen corrosion resistance under high temperature and high pressure.
11, tungsten (W): Tungsten melting point is higher than the major, is the precious alloy element. Tungsten and carbon form tungsten carbide with high hardness and wear resistance. Adding tungsten in tool steel can significantly improve red hardness and thermal strength, and be used as cutting tools and forging dies.
12 niobium (Nb): niobium can refine grain and reduce overheating sensitivity and temper brittleness of steel, increase strength, but decrease in plasticity and toughness. Adding niobium in ordinary low alloy steel can improve the resistance to atmospheric corrosion and hydrogen, nitrogen and ammonia corrosion at high temperature. NB can improve welding performance. Adding niobium in austenitic stainless steel can prevent intergranular corrosion.
13 cobalt (Co): cobalt is a rare precious metal. It is used in special steels and alloys, such as hot steel and magnetic materials.
14, copper (Cu): Wuhan Iron and steel smelting with Daye ore, often containing copper. Copper can increase strength and toughness, especially atmospheric corrosion. The disadvantage is prone to cracking during thermal processing, the copper content of more than 0.5% plastic significantly reduced. When the copper content is less than 0.50%, the weldability is not affected.
15, aluminum (Al): aluminum is commonly used in steel deoxidizer. A small amount of aluminum is added to the steel to refine the grain and improve the impact toughness, such as 08Al steel used for deep drawing. Aluminum also has oxidation resistance and corrosion resistance, aluminum and chromium, silicon combined, can significantly improve the high temperature steel peel resistance and high temperature corrosion resistance. The disadvantage of aluminum is that it affects the hot workability, weldability and machinability of the steel.
16, boron (B): the addition of a little boron in the steel can improve the compactness and hot rolling property of the steel, and increase the strength.
17, nitrogen (N): nitrogen can improve the strength of steel, low temperature toughness and weldability, increase aging sensitivity.
18, rare earth (Xt): rare earth element refers to the periodic table in the atomic number of 57-71 of the 15 lanthanide elements. These elements are all metals, but their oxides are very similar to earth, so they are customarily called rare earths.