Soderburg diagram of the studied crankshaft showed that the service operation point, which stands for mean and alternating stresses of the critical region (first crankpin fillet) was located in the safe region. Therefore, it can be concluded that fatigue fracture has not occurred in the crankshaft. SEM images of the fractured surface also showed cleavage fracture and put in evidence that the failure was brittle fracture. No sign of fatigue failure was observed.