Application of Homogenization Annealing to Suppress Silicon and Nickel Segregation in Ductile Iron

Abstract

This doctoral thesis deals with the comparison of different methods of alloying elements’ concentration measurement based on energy dispersive spectroscopy and also with the suitability of particular methods of quantitative assessment of heterogeneity of the spheroidal graphite cast iron matrix. The segregation curves construction, distribution coefficient and heterogeneity index formulation is also discussed. The notion “normalized distribution coefficient” is introduced newly. The goal of the thesis, which is to be achieved by means of evaluation of large experimental data sets, is the evaluation of applicability of homogenization annealing of spheroidal graphite cast iron with the aim to eliminate segregation of silicon, and mainly nickel, as pearlite- and carbide-forming agent at the border of an eutectic cell. The result is an optimized homogenization annealing schedule maximizing the suppression of silicon and nickel segregation while taking into account the minimization of financial expenses and risk of grain coarsening