Inoculation of cast iron

In recent years, there has been an increasing need and demand for processes to obtain carbide-free, thin-section grey iron castings. Inoculation is an established process not only for preventing carbide formation, but also for the control of graphite flake size and form in grey cast iron. After a brief consideration of the various theories advanced regarding inoculation, this paper reviews some of the developments that have taken place in inoculants and inoculating procedures for flake graphite cast iron. Some of the more recent inoculants, which have been tried, with various degrees of success have been briefly dealt with. Fading effects of inoculants and differences in the behaviour of the various inoculants have been outlined. Comparative study has been made of the various inoculants used, and the results obtained in some of the major grey iron foundries in India have been furnished. (Shri G.N. Rao, Scientist and Shri P.K. Gupte, Scientist & Head of General Metallurgy Division, National Metallurgical Laboratory, Jamshedpur)