Influence of Stress Mode on Failure Micromechanisms of Nodular Cast Iron

The paper deals with comparison of the failure micromechanisms of nodular cast iron at static, impact and fatigue stress. Several specimens of ferrite-pearlitic nodular cast irons with different content of ferrite in a matrix were used for metallographic analysis, mechanical tests and microfractographic analysis. Mechanical properties were found out by static tensile test, impact bending test and fatigue tests. The microfractographic analysis was made with use of scanning electron microscope on fracture surfaces of the specimens fractured by these mechanical tests. Fracture surfaces of analysed specimens are characteristic of mixed mode of fracture. Failure micromechanism of nodular cast irons is dependent on mode of stress.