Effects and working principle of chromium, nickel, titanium, carbon, manganese, silicon, vanadium, molybdenum and element in Alloy Steel

1. carbon (C): the carbon content in the steel increases, the yield point and the tensile strength increase, but the plasticity and impact degree decrease. When the carbon volume exceeds 0.23%, the welding performance of the steel will deteriorate, therefore, the carbon content of low alloy steel used for welding generally does not exceed 0.20%. High carbon content also reduces the atmospheric corrosion resistance of steel, and high carbon steel in the open-air field is prone to corrosion. In addition, carbon energy increases the cold brittleness and aging sensitivity of steel.

2. Silicon (SI): In the steelmaking process, silicon is added as the reducing agent and deoxidizing agent. Therefore, the killed steel contains 0.15-0.30% silicon. If the silicon content in the steel exceeds 0.50-0.60%, the silicon is an alloy element. Silicon can significantly improve the elasticity limit, yield point and tensile strength of steel, so it is widely used as spring steel. The strength can be increased by 15-1.0 by adding 1.2%-20% silicon to the tempered structural steel. Silicon can be combined with Molybdenum, tungsten and chromium to improve corrosion resistance and oxidation resistance. Silicon-containing low carbon steel 1-4%, with a very high magnetic conductivity, used for the electrical industry to do Silicon Steel. The increase in silicon will reduce the welding performance of steel.

3. manganese (Mn): in the steel-making process, manganese is a good deoxidizing agent and desulfurization agent, generally containing 0.30-0.50% manganese. When more than 0.70% of carbon steel is added, even if the "manganese steel" is used, the steel with higher strength and hardness not only has sufficient toughness, but also improves the quenching property of the steel, improve the thermal processing performance of steel. For example, 16mn steel is 40% higher than A3. Steel containing manganese 11-14% has a high wear resistance, used for excavator buckets, Ball Mill Liner, etc. The increase of manganese content weakens the corrosion resistance of steel and reduces the welding performance.

4. phosphorus (P): under normal conditions, phosphorus is a harmful element in steel. It increases the cold brittleness of steel, improves welding performance, reduces plasticity, and improves cold bending performance. Therefore, the phosphorus content in steel is usually less than 0.045%, And the quality steel is less demanding.

5. Sulfur (s): sulfur is usually harmful. The steel produces thermal brittleness, reduces the ductility and toughness of the steel, and causes cracks during forging and rolling. Sulfur is not good for welding performance, reducing corrosion resistance. Therefore, the sulfur content is usually less than 0.055%, And the quality steel requirement is less than 0.040%. Adding 0.08-0.20% of sulfur in steel can improve the machining performance, which is usually called free-cutting steel. 6. chromium (Cr): in steel and tool steel, chromium can significantly improve the strength, hardness and wear resistance, but also reduce the plasticity and toughness. Chrome can improve the oxidation resistance and corrosion resistance of steel, so it is an important alloy element of stainless steel and heat-resistant steel.

7. nickel (Ni): nickel can increase the strength of steel while maintaining good plasticity and toughness. Nickel has high corrosion resistance to acid and alkali, and rust and heat resistance at high temperatures. However, because nickel is a scarce resource, other alloy elements should be used as much as possible to replace nickel-chromium steel.

8. Molybdenum (Mo): molybdenum can refine the grain size of the steel, improve the quenching ability and thermal strength, and maintain sufficient strength and anti-creep ability at high temperature (stress at high temperature for a long time, deformation, called creep ). Adding molybdenum to structural steel can improve mechanical properties. It can also suppress the brittleness caused by fire of alloy steel. Red can be increased in tool steel.

9. Titanium (Ti): titanium is a medium-strength deoxidizing agent of steel. It can compact the internal structure of the steel, refine the grain strength, and reduce the aging sensitivity and cold brittleness. Improve welding performance. Adding appropriate titanium to chrome 18 nickel 9 stainless steel can avoid Intercrystal corrosion.

10. Vanadium (V): vanadium is an excellent deoxidizing agent of steel. Adding 0.5% of vanadium to the steel can refine the microstructure grain and increase the strength and toughness. Carbide formed by vanadium and carbon can improve the ability to resist Hydrogen Corrosion under high temperature and high pressure.

11. Tungsten (W): high melting point and large proportion of tungsten. It is an alloy element of guisheng. Tungsten and carbon form tungsten with high hardness and wear resistance. Adding tungsten to tool steel can significantly improve the red hardness and Thermal Strength, and can be used as cutting tool and forging die.

12. Nb (NB): Nb can refine the grain, reduce the overheating sensitivity and temper brittleness of the steel, increase the strength, but decrease the plasticity and toughness. Adding Nb in low alloy steel can improve the ability to resist atmospheric corrosion and resist hydrogen, nitrogen and ammonia corrosion at high temperature. NB can improve welding performance. Adding Nb to the stainless steel can prevent Intercrystal corrosion.

13. Cobalt (CO): Cobalt is a rare and precious metal. It is mostly used in special steel and gold, such as hot and strong steel and magnetic materials. 14. copper (Cu): the steel produced by the ore of WISCO, often containing copper. Copper improves strength and toughness, especially atmospheric corrosion. The disadvantage is that it is prone to thermal brittleness during hot processing, and the copper content is significantly reduced by over 0.5% plasticity. When the copper content is less than 0.50%, welding is not affected.

15. Aluminum (Al): aluminum is a common deoxidizing agent in steel. A small amount of aluminum can be added to the steel to refine the grain size and improve the impact toughness, for example, 08Al Steel for deep punch sheet. Aluminum also has antioxidant and corrosion resistance. Aluminum can be used with chromium and silicon to significantly improve the ability of high temperature and corrosion resistance of steel. The disadvantage of aluminum is that it affects the hot processing performance, welding performance and cutting performance of steel.

16. Boron (B): adding a trace of boron to the steel can improve the density and hot rolling performance of the steel, and increase the strength.

17. nitrogen (N): nitrogen can improve the strength, low temperature toughness and welding property of the steel, and increase the aging sensitivity.

18. Rare Earth (XT): a rare earth element refers to 15 lanthanum elements whose suborders are 57-71 in the periodic table of elements. These elements are all metal, but their oxides are very similar to "Earth", so they are often called rare earth. Adding rare earth in steel can change the composition, morphology, distribution and properties of inclusions in steel, thus improving the properties of steel, such as toughness, welding and cold processing. Adding rare earth to the plough steel can improve wear resistance.