Analysis of Nuclei in a Heavy-Section Nodular Iron Casting

Abstract:

The microstructure of heavy section nodular graphite cast irons often presents a bimodal distribution of nodule size associated with so-called primary and secondary graphite nucleation. It has been found that the nuclei in both types of nodules consist mainly in magnesium sulphide. However, nuclei in primary nodules contain some traces of calcium and are thus related with the inoculation treatment. On the contrary, nuclei in secondary nodules do not contain any element that could be associated to inoculation. It is suggested they form in the late stage of the eutectic reaction as a result of microsegregation build-up in magnesium and sulphur.

• Periodical: Materials Science Forum (Volume 925)
• Pages: 173-180
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.925.173
• Online since: June 2018
• Authors: Mayerling Martinez*, Bernadette Domengès, Eric Hug, Jacques Lacaze
• Keywords: Heavy Section Casting, Nodular Cast Iron, Nuclei

References

[1] H.M. Muhmond, H. Fredriksson, Relationship between inoculants and the morphologies of MnS and graphite in gray cast iron, Metall. Mater. Trans. B 44B (2013) 283-298.

DOI: 10.1007/s11663-012-9768-6

[2] I. Asenjo, P. Larrañaga, J. Sertucha, R. Suárez, I. Ferrer, J. M. Gómez, J. Lacaze, Effect of mould inoculation on formation of chunky graphite in heavy section spheroidal graphite cast iron parts, Int. J. Cast Met. Res. 20 (2007) 319-324.

DOI: 10.1179/136404608x286138

[3] J. Sertucha, R. Suarez, I. Asenjo, P. Larranaga, J. Lacaze, I. Ferrer, S. Armendariz, Thermal analysis of the formation of chunky graphite during solidification of heavy-section spheroidal graphite iron parts, ISIJ Int. 49 (2009) 220-228.

DOI: 10.2355/isijinternational.49.220

[4] T. Yaguchi, T. Kamino, T. Ishitani, R. Urao, Method for cross-sectional transmission electron microscopy specimen preparation of composite materials using a dedicated focused ion beam system, Microsc. and Microanal. 5 (1999) 365–370.

DOI: 10.1017/s1431927699000203

[5] T. Skaland, O. Grong, T. Grong, A model for the graphite formation in ductile cast iron: Part 1. inoculation mechanisms, Metall. Trans. 24A (1993) 2321-2345.

DOI: 10.1007/bf02648605

[6] J. Lacaze, Trace elements and graphite shape degeneracy in nodular graphite cast irons, Int. J. MetalCasting, 11 (2017) 44-51.

DOI: 10.1007/s40962-016-0115-6

[7] G. Alonso, D.M. Stefanescu, P. Larranaga, R. Suarez, E. de la Fuente, Reassessment of nucleation models for spheroidal graphite through advanced SEM analysis, AFS Congress Proc., 2017, paper 17-031.

[8] Y. Igarashi and S. Okada, Observation and analysis of the nucleus of spheroidal graphite in magnesium-treated ductile iron, Int. J. Cast Met. Res. 11 (1998) 83-88.

DOI: 10.1080/13640461.1998.11819261

[9] K. Theuwissen, M. Véron, L. Laffont, J. Lacaze, Crystallography of graphite spheroids in cast iron, Int. J. Cast Met. Res. 29 (2016) 12-16.

DOI: 10.1080/13640461.2016.1142233

[10] K. Theuwissen, J. Lacaze, L. Laffont, Structure of graphite precipitates in cast iron, Carbon 96 (2016) 1120-1128.

DOI: 10.1016/j.carbon.2015.10.066