Fading and graphite nucleation sites in grey iron inoculated using silicon carbide

Abstract

The most commonly used inoculants for producing grey iron are ferrosilicon based, but also there are reports indicating that silicon carbide can act as inoculant. There are few published studies of fading and nucleation sites of graphite when silicon carbide is used as inoculant, thus the understanding of the inoculation effect of silicon carbide is incomplete. To study these two aspects, fading and graphite nucleation sites, an ASTM class 35B grey iron inoculated with silicon carbide was produced and characterized. The results were compared with an ASTM class 35B grey iron inoculated with a ferrosilicon base inoculant and without inoculation. It was found that the effect of the silicon carbide was comparable to the ferrosilicon base inoculant and fading was similar. In addition, the graphite nucleation sites in the grey iron inoculated with silicon carbide were irregular shaped manganese sulfides larger than the nuclei in the grey iron inoculated with ferrosilicon, which suggest a similar nucleation mechanism for both inoculants.

Experimental assessment of the gray cast iron production by inoculant injection

“…So, inoculants are added to produce heterogeneous nucleation of these graphite flakes and obtain the desired distribution. Improving manufacturing processes for cast iron is always needed and many gray iron studies focused on theories of graphite lamellar nucleation [7,8], pre-inoculation treatments [8,9], microstructure and mechanical properties [10][11][12], and inoculation fading effect [13,14] have been widely investigated but, few studies have been focused on the inoculant addition method. There are two main methods of inoculation: ladle and late inoculation.…”