metallography dot com logo This is a continuation of the article by Janina Radzikowska, Senior Metallographer, The Foundary Research Institute (Instytut Odlewnictwa) Kraków, Poland . It was originally published by Buehler in Tech-Notes, Volume 2, Issue 2. Itis reproduced here with the kind permission of the Editor, Mr. George Vander Voort, former Director, Research and Technology at Buehler, who granted it while still at Buehler.

Nodular Iron
Ductile iron specimens can have a wide range of matrix structures depending upon composition and as-cast cooling rate. Figure 14 shows a fully ferritic matrix after etching with 4% nital. Figure 15 shows a specimen with a pearlitic matrix and ferrite surrounding the nodules, while Figure 16 shows an example where a very small amount of ferrite remains around each nodule.
ferritic matrix ductile iron 100x Figure 14. Fully ferritic matrix (note ferrite grain boundaries) of a ductile iron specimen etched with 4% nital, 100x.
ductile iron w/ferrite and pearlite 100x Figure15. Ductile iron specimen with substantial amounts of ferrite and pearlite etched with 4% nital, 100x.
ductile iron w/pearlitic matrix 100x Figure 16. Ductile iron specimen with a pearlitic matrix and a small amount of ferrite surrounding the nodules etched with 4% nital, 100x.

White Cast Iron

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