2. Introduction
Molybdenum steel can be regarded as a kind of special steel, which has excellent performance and is widely used in aviation, aerospace, shipbuilding, automobile, chemical industry and construction industry. Molybdenum steel, also known as molybdenum, is a kind of high temperature and special alloy steel which contains molybdenum (Mo) elements as the main alloying element. The molybdenum content of molybdenum steel is generally more than 0.5%. Molybdenum steel has good comprehensive properties, so it is widely used in the manufacture of turbine blades, compressor blades and aircraft bearing components.
3. Properties of Molybdenum Steel
3.1 High Temperature Strength
At high temperatures, molybdenum steel can retain greater strength and hardness than other common steel, and its tensile strength and hardness of surface layer are much higher than molybdenum-free steel. This excellent thermal strength is due to the formation of molybdenum carbide which has greater toughness and corrosion resistance and higher temperature strength than other common steel.
3.2 High Creep Resistance
Creep is the combination of plastic deformation and creepage in materials under constant load, and its failure time is much lower than that of common steel. Molybdenum steel has higher creep resistance than molybdenum-free steel due to its stronger stability and thermal strength ability.
3.3 Corrosion Resistance
Molybdenum steel is more corrosion resistant than molybdenum-free steel, which is mainly due to its unique molybdenum oxide layer which provides good protection performance, making molybdenum steel more corrosion resistant.
3.4 Thermal Stability
Molybdenum steel is more temperature stable than molybdenum-free steel and can maintain excellent strength at higher temperatures. This temperature stability property makes molybdenum steel an ideal material for industrial and manufacturing applications which have high temperature requirements.
3.5 Toughness
Molybdenum steel is tougher than molybdenum-free steel and is able to resist more torque and impact before breaking. This superior toughness makes molybdenum steel ideal for applications where high levels of wear and tear are expected.
3.6 Sealing Performance
Molybdenum steel has good sealing performance, so it is widely used in high pressure gas pipelines and vessels, and also in other applications where corrosion resistance and good sealing performance are needed.
4. Applications of Molybdenum Steel
Molybdenum steel plays an important role in many industries. Some of its major applications include:
4.1 Aircraft Components
Molybdenum steel is widely used in the manufacture of aviation equipment components, such as bearings, fasteners and compressor blades. These components need to withstand large temperature changes during aircraft operation and require high strength and creep resistance.
4.2 Automotive Components
Molybdenum steel is used in the production of various automotive components, such as engine cylinders, crankshaft bearings, exhaust valves and piston crowns. These components need to be resistant to high temperature and wear and tear, and molybdenum steel provides the properties necessary for durability.
4.3 Industrial Furnaces and Components
Molybdenum steel is widely used in industrial furnaces and components, such as heating elements, muffles, heating tubes and seals. These components need to resist extreme temperature and corrosion, and molybdenum steel provides the necessary toughness and corrosion resistance.
5. Standard of GB/T3649-1987
GB/T3649-1987 is a Chinese national standard issued by the State Bureau of Quality and Technical Supervision in 1987, which stipulates the chemical composition and mechanical properties of molybdenum steel. According to this standard, the allowable range of carbon content is 0.15-0.25%, the allowable range of manganese content is 0.4-0.8%, the allowable range of molybdenum content is 0.4-0.8%, the minimum tensile strength requirement is 310 MPa, and the minimum value in the yield section must be 270 MPa. The requirements for impact energy and hardness should meet certain requirements as well.
6. Conclusion
Molybdenum steel is a kind of high temperature special alloy steel, which contains molybdenum (Mo) as the main alloying elements. Molybdenum steel has excellent comprehensive properties, such as high temperature strength, creep resistance, corrosion resistance, thermal stability and toughness. Due to these excellent properties, molybdenum steel is widely used in aviation, aerospace, automobile, chemical industry and construction industry. The Standard of GB/T3649-1987 issued by the State Bureau of Quality and Technical Supervision stipulates the chemical composition and mechanical properties of molybdenum steel.
