In situ XRD study of the graphite surface layer formation during thermal cycling of cast iron

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

During service, parts made of spheroidal graphite (SG) cast iron may be submitted to temperature cycling. It is experimentally known that the growth of graphite can not be explained by the volume diffusion of carbon. Recent results obtained for the desaturation of the austenite in a SG cast iron confirmed the existence of a significant difference between the experiment and the theoretical predictions based on the volume diffusion of carbon. According to stress state calculations, one possible explanation for this discrepancy could rely on the existence of a strong hydrostatic component gradient close to the austenite / graphite interface that would act as a barrier for the carbon diffusion across this interface. However, this discrepancy seems not to be present in the case of the carbon diffusion to the free surface of the material when cycled under vacuum. In situ high temperature XRD has been used to follow the growth of the graphite layers on the free surface of the samples during cycling between 800 and 950°C. The results of these XRD tests are compared to previous results concerning the volume diffusion of carbon during graphitization.

Original languageEnglish
Title of host publicationAdvanced Materials Forum II: Proceedings of the II International Materials Symposium: Materials 2003 and XI Encontro da Sociedade Portuguesa de Materiais, 2003 ATERIAIS
EditorsR. Martins, E. Fortunato, I. Ferreira, C. Dias
PublisherTrans Tech Publications Ltd
Pages326-329
Number of pages4
Publication statusPublished - 29 Jul 2004
EventAdvanced Materials Forum II: Proceedings of the II International Materials Symposium: Materials 2003 and XI Encontro da Sociedade Portugesa de Materials, 2003 ATERIAIS - Caparica, Portugal
Duration: 14 Apr 200316 Apr 2003

Publication series

NameMaterials Science Forum
PublisherTrans Tech Publications Ltd
Volume455-456
ISSN (Print)0255-5476

Conference

ConferenceAdvanced Materials Forum II: Proceedings of the II International Materials Symposium: Materials 2003 and XI Encontro da Sociedade Portugesa de Materials, 2003 ATERIAIS
CountryPortugal
CityCaparica
Period14/04/0316/04/03

Keywords

  • Cast iron
  • Graphitization
  • Metals characterization
  • X-ray diffraction

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    Fernandas, F. M. B., Silva, R. J. C., & Gomes, A. (2004). In situ XRD study of the graphite surface layer formation during thermal cycling of cast iron. In R. Martins, E. Fortunato, I. Ferreira, & C. Dias (Eds.), Advanced Materials Forum II: Proceedings of the II International Materials Symposium: Materials 2003 and XI Encontro da Sociedade Portuguesa de Materiais, 2003 ATERIAIS (pp. 326-329). (Materials Science Forum; Vol. 455-456). Trans Tech Publications Ltd.