The role of alloying elements (Cobalt(Co), Manganese(Mn), Phosphorus(P), Rare earth (Re))
It is precise because of the variety of elements, and the existence of various forms. Therefore, their role in steel is also variable. Let us finally explore the remaining alloying elements.
(1)Cobalt(Co)
Cobalt often uses in the special steel and alloy. The cobalt containing high-speed steel has high high-temperature hardness. Simultaneous addition of molybdenum to maraging steel. It can get an ultra high hardness and good overall mechanical properties. In addition, cobalt is also an important alloying element in heat-strength steel and magnetic materials.
Cobalt can reduce hardenability of steel. Therefore, adding cobalt alone to carbon steel will reduce the overall mechanical properties after quenching and tempering. Cobalt can strengthen ferrite. Adding to carbon steel can improve the hardness of steel, yield point and tensile strength under an annealed or normalized state. However, it has an adverse effect on the elongation and the reduction of the area, and the impact toughness also decreases as the cobalt content increases. Since cobalt has antioxidant properties, it is used in heat resistant steels and heat resistant alloys. It also shows its unique role in cobalt-based alloy gas turbines.
(2)Manganese(Mn)
Manganese is a good deoxidizer and desulfurizer. Steel generally contains a certain amount of manganese. It can eliminate or reduce the hot brittleness of steel caused by sulfur, thereby improving the hot workability of steel.
A solid solution of manganese and iron to increase the hardness and strength of ferrite and austenite in steel. At the same time, it is an element of carbide formation. Enter into cementite and replace a part of iron atoms. Manganese plays a role in refining pearlite by lowering the critical transition temperature in steel. Also indirectly enhances the strength of pearlitic steel. The ability of manganese to stabilize austenite is second only to nickel, and it also strongly increases the hardenability of steel. Manganese with a content of not more than 2% can be made into a variety of alloy steels by blending with other elements.
Manganese is rich in resources and diverse in performance, and has been widely used. For example, carbon structural steel with high manganese content, spring steel. In high carbon and high manganese wear-resistant steel, the manganese content can reach 10% to 14%. It will have good toughness after solution treatment. When deformed by receiving an impact, the surface layer will be strengthened by deformation and has high wear resistance. Manganese and sulfur form a higher melting point of MnS, which prevents hot brittleness due to FeS. Manganese has a tendency to increase the grain coarsening of steel and temper brittleness sensitivity. If the smelting and pouring and chilling are not properly cooled, it is easy to make the steel produce white spots.
(3)Phosphorus(P)
Phosphorus has strong solid solution strengthening and cold work hardening in steel. As an alloying element added to the low-alloy structural steel, it can improve its strength and the atmospheric corrosion resistance of steel, but it will reduce its cold stamping performance. Phosphorus used combined with sulfur and manganese can increase the cutting performance of steel and increase the surface quality of the machined parts. It is used for easy-cutting steel, so the phosphorus content of the easy-cutting steel is also relatively high. Phosphorus is used in ferrite, although it can increase the strength and hardness of the steel. But the biggest harm is that the segregation is serious, the temper brittleness is increased, and the plasticity and toughness of the steel are significantly increased. The phenomenon that the steel is easily brittle during cold working is also called the phenomenon of "cold brittleness". Phosphorus also has an adverse effect on weldability. Phosphorus is a harmful element and should be strictly controlled. The general content is not more than 0.03% to 0.04%.
(4)Rare earth(Re)
The term "rare earth element" as used herein refers to a lanthanide element having an atomic number from 57 to 71 in the periodic table of the elements plus a number 21 scandium and a 39 yttrium, a total of 17 elements. They are close in nature and difficult to separate. Unseparated is called mixed rare earth, which is cheaper. Rare earth elements can improve the plasticity and impact toughness of wrought steel, especially in cast steel. It can improve the creep resistance of heat resistant steel electrothermal alloys and high temperature alloys.
Rare earth elements can also improve the oxidation resistance and corrosion resistance of steel. The effect of oxidation resistance exceeds that of elements such as silicon, aluminum, and titanium. It can improve the fluidity of steel, reduce non-metallic inclusions, and make steel structure dense and pure.
Adding appropriate rare earth elements to common low-alloy steels has good deoxidation and desulfurization effects, improves impact toughness, and improves anisotropic properties. Rare earth elements increase the oxygen resistance of the alloy in iron-chromium-aluminum alloys. The fine grain of the steel is maintained at a high temperature, and the high-temperature strength is increased, so that the life of the electrothermal alloy is remarkably improved.
(1)Cobalt(Co)
Cobalt often uses in the special steel and alloy. The cobalt containing high-speed steel has high high-temperature hardness. Simultaneous addition of molybdenum to maraging steel. It can get an ultra high hardness and good overall mechanical properties. In addition, cobalt is also an important alloying element in heat-strength steel and magnetic materials.
Cobalt can reduce hardenability of steel. Therefore, adding cobalt alone to carbon steel will reduce the overall mechanical properties after quenching and tempering. Cobalt can strengthen ferrite. Adding to carbon steel can improve the hardness of steel, yield point and tensile strength under an annealed or normalized state. However, it has an adverse effect on the elongation and the reduction of the area, and the impact toughness also decreases as the cobalt content increases. Since cobalt has antioxidant properties, it is used in heat resistant steels and heat resistant alloys. It also shows its unique role in cobalt-based alloy gas turbines.
(2)Manganese(Mn)
Manganese is a good deoxidizer and desulfurizer. Steel generally contains a certain amount of manganese. It can eliminate or reduce the hot brittleness of steel caused by sulfur, thereby improving the hot workability of steel.
A solid solution of manganese and iron to increase the hardness and strength of ferrite and austenite in steel. At the same time, it is an element of carbide formation. Enter into cementite and replace a part of iron atoms. Manganese plays a role in refining pearlite by lowering the critical transition temperature in steel. Also indirectly enhances the strength of pearlitic steel. The ability of manganese to stabilize austenite is second only to nickel, and it also strongly increases the hardenability of steel. Manganese with a content of not more than 2% can be made into a variety of alloy steels by blending with other elements.
(3)Phosphorus(P)
Phosphorus has strong solid solution strengthening and cold work hardening in steel. As an alloying element added to the low-alloy structural steel, it can improve its strength and the atmospheric corrosion resistance of steel, but it will reduce its cold stamping performance. Phosphorus used combined with sulfur and manganese can increase the cutting performance of steel and increase the surface quality of the machined parts. It is used for easy-cutting steel, so the phosphorus content of the easy-cutting steel is also relatively high. Phosphorus is used in ferrite, although it can increase the strength and hardness of the steel. But the biggest harm is that the segregation is serious, the temper brittleness is increased, and the plasticity and toughness of the steel are significantly increased. The phenomenon that the steel is easily brittle during cold working is also called the phenomenon of "cold brittleness". Phosphorus also has an adverse effect on weldability. Phosphorus is a harmful element and should be strictly controlled. The general content is not more than 0.03% to 0.04%.
(4)Rare earth(Re)
The term "rare earth element" as used herein refers to a lanthanide element having an atomic number from 57 to 71 in the periodic table of the elements plus a number 21 scandium and a 39 yttrium, a total of 17 elements. They are close in nature and difficult to separate. Unseparated is called mixed rare earth, which is cheaper. Rare earth elements can improve the plasticity and impact toughness of wrought steel, especially in cast steel. It can improve the creep resistance of heat resistant steel electrothermal alloys and high temperature alloys.
Rare earth elements can also improve the oxidation resistance and corrosion resistance of steel. The effect of oxidation resistance exceeds that of elements such as silicon, aluminum, and titanium. It can improve the fluidity of steel, reduce non-metallic inclusions, and make steel structure dense and pure.
Adding appropriate rare earth elements to common low-alloy steels has good deoxidation and desulfurization effects, improves impact toughness, and improves anisotropic properties. Rare earth elements increase the oxygen resistance of the alloy in iron-chromium-aluminum alloys. The fine grain of the steel is maintained at a high temperature, and the high-temperature strength is increased, so that the life of the electrothermal alloy is remarkably improved.
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