Competitive Nucleation in Grey Cast Irons

Abstract

Cast irons are good examples of materials which are more sensitive to chemical composition and production conditions. In this research to improve casting quality, solidification and nucleation process in grey cast iron was investigate. In particular, attempts have been made to rationalize variation in eutectic cells with nucleation sites and eutectic solidification undercooling. Four castings with different diameter and similar chemical composition and pouring temperature and different inoculant percentage was casted. The cooling curve and maximum and minimum undercooling for each castings was measured. Also optical metallography and image analyzer has been used to determine the average eutectic cells diameter, and linear and surface densities, and volume density was calculated. The results of this research show a competitive behavior between nucleation sites and eutectic undercooling. Higher nucleation sites and higher eutectic undercooling cause higher eutectic cell density. But increasing nucleation sites by introducing inoculants to molten metal, is accompanied with reduction in eutectic undercooling. It means that inoculation and undercooling have opposite effect on each other. So, to achieve maximum cell density, it is necessary to create an optimization between these parameters.

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.…”

Archives of Foundry Engineering

“…In the present study, all types of cast iron are combined into one product group without any additional details. No metallurgical country can do without cast iron production [1].…”