Crank connecting rods are generally forged and ductile iron. The key is the application, the need to do strength calculation.
The crankshaft and crank on the engine are 45 steel forgings or ductile iron, the connecting rod is generally 40Gr alloy structural steel, modulation treatment.
Crankshafts generally use high strength, impact toughness and wear resistance of good quality carbon structural steel, high quality carbon steel or high strength ductile iron forging or casting.
