Microstructural Analysis of the Failure of a Cast Iron Cylinder Head of a Thermoelectrical Plant Motor

Large motors, such as those that propel ships or generate energy for thermoelectrical plants, for instance, use cylinder heads produced with nodular cast iron. Such components are manufactured by a casting process which must be strictly controlled to prevent the appearance of defects that may spoil the performance of the component in service. When these defects arise, they usually lead to the failure of the cylinder head, mainly causing fluids leakage that can harm or even impede the motor performance. In this study, the microstructure of the material was characterized, with the purpose of investigating the possible causes of the failure, through the use of techniques such as optical microscopy and scanning electron microscopy. Brinell hardness tests were also performed. The results revealed that inadequate casting procedures probably caused the defects and subsequent failure of the cylinder head.