The correct answer is: D. Axles and springs.
Vanadium steel is a type of steel that contains vanadium as an alloying element. Vanadium is a strong, ductile, and corrosion-resistant metal. It is added to steel to improve its strength, toughness, and fatigue resistance. Vanadium steel is used in a variety of applications, including axles and springs.
Axles are shafts that transmit power from the engine to the wheels. They must be strong enough to support the weight of the vehicle and the load it is carrying. They must also be able to withstand the stress of vibration and shock. Vanadium steel is ideal for axles because it is strong, tough, and fatigue-resistant.
Springs are used to absorb shock and vibration. They must be able to withstand a lot of force without breaking. Vanadium steel is ideal for springs because it is strong and ductile.
The other options are incorrect because vanadium steel is not typically used for those applications.
- Railway switches and crossing are made from a variety of materials, including steel, iron, and concrete. Vanadium steel is not typically used for these applications because it is not as strong as other materials, such as steel.
- Bearing balls are made from a variety of materials, including steel, ceramic, and plastic. Vanadium steel is not typically used for bearing balls because it is not as hard as other materials, such as ceramic.
- Magnets are made from a variety of materials, including iron, nickel, and cobalt. Vanadium steel is not typically used for magnets because it is not as magnetic as other materials, such as iron.