Investigation of Material Properties Based on 3D Graphite Morphology for Compacted Graphite Iron

The strength and thermal conductivity of compacted graphite iron (CGI) are crucial performance indicators in its engineering application. The presence of graphite in CGI significantly influences the two properties. In the previous studies, graphite in CGI was often described using two-dimensional (2D) morphology. In this study, the three-dimensional (3D) size, shape, and distribution of graphite in CGI were analyzed using X-ray tomography. Based on this, a new method is introduced to calculate the 3D vermicularity and compare it with the 2D vermicularity in terms of tensile properties and thermal conductivity. The results demonstrate that vermicular graphite exhibits greater connectivity in 3D observation compared to 2D observation. Therefore, the calculation method of 3D vermicularity is determined by considering the surface area and volume of the connected graphite. Then a linear relationship between 3 and 2D vermicularity has been observed. By comparing the correlation coefficient, it has been found that the 3D vermicularity offers a more accurate method to establish the relationship among graphite morphology, thermal conductivity and tensile property of CGI.