Quantitative analysis of the irregularity of graphite nodules in cast iron

Three methods have been introduced in this paper to measure the irregularity of graphite nodules in one-, two- and three-dimensional (1D, 2D and 3D) space. In the study on the boundaries of graphite nodules in ductile iron, it was found that the measured length obeys Richardsonʹs fractal equation. By comparing the dimension with the shape factor, it was observed that the fractal dimension is a more sensitive parameter influencing the mechanical properties of ductile iron. Study of the 2D shape of graphite nodules in malleable iron showed that the relationship between the measured area and radius follows a power law. The aggregates of graphite can be characterized by their fractal dimension. The latter also reflects the change in the state of graphite aggregates during the annealing process. A variation–correlation method was applied to the quantitative description of the 3D graphite surfaces imaged by a scanning electron microscope. The results showed that the fractal dimension can be used to characterize accurately the irregularity of graphite surfaces processed by different inoculation methods.