What materials are typically used to make cast crankshafts?

Cast crankshafts are primarily made from ductile cast iron and cast steel due to the properties these materials offer. Ductile cast iron, also known as nodular iron, provides excellent strength and shock resistance, which is crucial for withstanding the high stresses and vibrations encountered during engine operation. Additionally, ductile cast iron has good wear resistance, which contributes to the longevity of the crankshaft.

Cast steel is also widely used for crankshafts because it possesses a high tensile strength and ductility, allowing it to endure the dynamic loads experienced in an engine. The combination of these materials allows for the production of crankshafts that can effectively manage the demands of modern engines, maintaining performance and reliability over time.

The other materials listed, such as aluminum and plastic, lack the necessary strength and could lead to failure under the high pressures and operating conditions of an engine. Stainless steel and bronze, while offering some mechanical properties, are not typically chosen for this application due to their cost and physical characteristics compared to ductile cast iron and cast steel. Finally, iron and magnesium, while magnesium is a lightweight metal, it does not offer the same durability and structural integrity required for a crankshaft, making it less suitable for this critical component.