Connecting rod is, usually, made from Medium carbon steel

Wrought Iron is the purest form of iron; although it may contain traces of carbon. Wrought iron is least corrosion resistant, It is usually made by ‘‘puddling process’’ and besides iron contains a small quantity of slag. It is very costly and its use has been almost totally replaced by cheaper steel. However, for some components like chain-links and Crane-hooks wrought iron is still the preferred raw material.