Synchrotron quantification of graphite nodule evolution during the solidification of cast iron. (15th August 2018)

• Record Type: Journal Article
• Authors: Azeem, M.A.; Bjerre, M.K.; Atwood, R.C.; Tiedje, N.; Lee, P.D.
• Is Part Of: Acta materialia. Volume 155(2018)
• Page Start: 393
• Page End: 401
• Publication Date: 2018-08-15
• Subjects: Graphite morphology -- Cast iron -- Synchrotron radiation computed tomography -- Nucleation and growth -- Growth kinetics; Materials -- Periodicals; Materials science -- Periodicals; Materials -- Mechanical properties -- Periodicals; Metallurgy -- Periodicals; Chemistry, Inorganic -- Periodicals; 620.112
• DOI: 10.1016/j.actamat.2018.06.007
• Languages: English
• ISSNs: 1359-6454

Abstract

Abstract: In cast iron, graphite develops in conjunction with the metallic matrix during solidification. The morphology and distribution of the embedded graphite is pivotal for mechanical properties from yield strength to fatigue. A novel high temperature environmental cell was developed and combined with in situ synchrotron tomography to investigate and quantify microstructural evolution, including graphite nodule nucleation and growth rates in ductile cast iron. The mechanisms of degenerate graphite nodule formation were also revealed. The formation of a coherent primary gamma phase dendritic network before the graphite nucleation is demonstrated. The graphite nodule nucleation rate, mobility and growth rates are compared to classical models, highlighting the limitations in these models. The results provide unique insights to tune the temperature pathways during cast iron solidification to achieve desired uniform rounded graphite morphologies and size distributions. Graphical abstract: Image 1