Manganese is a good deoxidizer and desulfurizer. Steel generally contains a certain amount of manganese, which can eliminate or weaken the hot brittleness of steel caused by sulfur, thereby improving the hot workability of steel.
The solid solution formed by manganese and iron improves the hardness and strength of ferrite and austenite in steel; it is also an element that forms carbides and enters cementite to replace some iron atoms. Manganese in steel lowers the critical transformation temperature. It plays the role of refining pearlite and indirectly improves the strength of pearlitic steel. Manganese's ability to stabilize austenite structure is second only to nickel, and it also strongly increases the hardenability of steel. A variety of alloy steels have been made with manganese content not exceeding 2% and other elements.
Manganese has the characteristics of abundant resources and diverse efficiencies, and has been widely used, such as carbon structural steel and spring steel with high manganese content.
In high-carbon and high-manganese wear-resistant steel, the manganese content can reach 10% to 14%. It has good toughness after solid solution treatment. When deformed by impact, the surface layer will be strengthened due to deformation, and has high durability. Abrasive.
Manganese and sulfur form MnS with a higher melting point, which can prevent hot embrittlement caused by FeS. Manganese has a tendency to increase grain coarsening and temper brittleness susceptibility of steel. If the cooling is improper after smelting, pouring and forging, it is easy to cause white spots in the steel.
Al Aluminum is mainly used for deoxidation and grain refinement. Promotes the formation of a hard and corrosion-resistant nitrided layer in nitrided steel. Aluminum can inhibit the aging of low carbon steel and improve the toughness of steel at low temperatures. When the content is high, it can improve the oxidation resistance of steel and the corrosion resistance in oxidizing acids and H2S gas, and can improve the electrical and magnetic properties of steel. Aluminum has a great solid solution strengthening effect in steel, improving the wear resistance, fatigue strength and core mechanical properties of carburized steel.
In refractory alloys, aluminum and nickel form compounds to improve the smelting strength. Iron-chromium-aluminum alloys containing aluminum have characteristics close to constant resistance and excellent oxidation resistance at high temperatures, and are suitable for electrosmelting alloy materials and chromium-aluminum alloys. Resistance wire.
When certain steels are deoxidized, if too much aluminum is used, the steel will produce abnormal structures and tend to promote graphitization of the steel. In ferritic and pearlitic steels, when the aluminum content is high, it will reduce its high-temperature strength and toughness, and bring some difficulties to smelting and pouring.
