Here's why:
* Strength: Gudgeon pins are subjected to high forces due to the reciprocating motion of the piston, so they need to be incredibly strong to withstand the stress. Heat-treated steel provides this strength.
* Wear Resistance: The gudgeon pin sits within the piston and connects to the connecting rod, undergoing a lot of friction. Heat-treated steel offers excellent wear resistance, ensuring the pin doesn't wear down quickly.
* Durability: Heat treatment strengthens the material, making it more resistant to fatigue and failure.
While steel is the most common material, other options are sometimes used depending on the application:
* Aluminum alloys: Can be used in lightweight engines, but might require special coatings or treatments for wear resistance.
* Titanium alloys: Offer high strength and light weight, but can be more expensive.
Ultimately, the choice of material for a gudgeon pin depends on the specific requirements of the engine design.