1. Introduction
Grey cast iron is a typical brittle metallic material because of its low ductility. This brittle behaviour
shows up in tensile testing where the elongation is nearly zero. It is well known that Gray iron is relatively
inexpensive and extensively used in applications where the material is subjected to compressive load, such
as disc brake rotors and hydraulic valves [1]. The microstructure of grey cast iron is made up of free carbon
in the form of flake graphites and a matrix of steel. Flake graphites are formed during solidification and
basically control the mechanical properties of grey iron. For high strength cast iron, besides the necessity
to refine graphite flakes by inoculation of the iron melt, alloying to alter the matrix structure plays an
important role [2].
In this study, the causes of fracture of a compressor rotor made from grey cast iron are investigated.
Manufacturing of the rotor is carried out in a military factory. A photograph of the compressor rotor and
stator as manufactured in the factory are given in Fig. 1. A number of mechanical and microstructure
analyses are carried out to determine the causes of fracture.
* Corresponding