Effect of copper content on the microstructure and mechanical properties of a modified nodular iron

During the drilling operation of two crankshafts, both made of modified nodular iron, the drilling tool failed in one of them and a failure analysis was conducted on the two crankshafts. Results indicate that in the crankshaft where the drilling tool failed had a finer pearlitic microstructure with a higher hardness compared with the other. This difference in the microstructure and hardness was due to the higher content of carbon and copper in the matrix of the first crankshaft analyzed.