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

doi:10.1007/s40195-024-01664-6

Abstract

Abstract:

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.

Key words: Compacted graphite iron, 3D graphite morphology, X-ray tomography, Thermal conductivity, Tensile property

Chenglu Zou, Yan Zhao, Gang Zhu, Jianchao Pang, Shaogang Wang, Yangzhen Liu, Feng Liu, Shouxin Li, Zhefeng Zhang. Investigation of Material Properties Based on 3D Graphite Morphology for Compacted Graphite Iron[J]. Acta Metallurgica Sinica (English Letters), 2024, 37(6): 1077-1086.

Figures/Tables 10

Table 1 Chemical compositions of CGIs (wt%)

Sample	CE	C	Si	Mn	P	S	Cu	Mo	Fe	Mg-Re
Sa1	4.40	3.70	2.30	0.65	0.05	0.03	0.60	-	Bal.	0.6
Sa2	4.50	3.70	2.30	0.20	0.05	0.03	0.60	0.40	Bal.	0.7
Sa3	4.50	3.70	2.30	0.20	0.05	0.03	0.60	0.40	Bal.	0.8

Fig. 1 Shape and dimension of specimens: a thermal diffusivity specimen, b tensile specimen

Fig. 2 2D morphologies of different CGI samples: a Sa1 without etch, b Sa1 etched, c Sa2 without etch, d Sa2 etched, e Sa3 without etch; f Sa3 etched

Fig. 3 3D graphite morphologies of different CGI samples: a, b Sa1, c, d Sa2, e, f Sa3

Fig. 4 Relationship between thermal conductivity and temperature a, tensile engineering stress-strain curves b

Fig. 5 3D versus 2D vermicularities for Sa1, Sa2 and Sa3

Fig. 6 3D graphite particle distribution in sample groups of Sb and Sc: a Sb1, b Sb2, c Sb3, d Sb4, e Sc1, f Sc2, g Sc3, h Sc4

Fig. 7 Relationship of 3D and 2D vermicularities of samples: a group Sb, b group Sc

Fig. 8 Relationship between 2D/3D vermicularity and thermal conductivity: a 100 °C, b 300 °C, c 500 °C, d the influence of temperature on linear correlation coefficients

Fig. 9 Relationship between 2D/3D vermicularity and tensile properties: a tensile strength, b yield strength

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