Bachinskyi Y. Influence of modifying in precrystallization period process on structure formation and properties of ductile cast iron thin-walled products.

The thesis is devoted to creation of new instant ferrosilicon-magnesium master alloys with complex impact on the melt on the basis of modifying alloys interaction with molten cast iron regularities investigation and to development of modifying in precrystallization period process for thin-walled ductile cast iron as-cast castings reception without chill with fine structure and improved properties. The phase composition of modifying alloys containing such active chemical elements as Mg, Ca, RE, Si is researched. The chemical composition changes in surface layer of modifying alloys melted in liquid iron and its influence on physico-chemical processes in the contact zone are investigated. Kinetic modes of FeSi and FeSiMg alloys dissolution in the cast iron melt are determined. Developed a new brands of instant FeSiMg master alloys with a higher content of silicon or calcium, barium, vanadium, manganese or copper, which using provides a high quality of as-cast ductile iron with the strength and elongation, that significantly exceeds the corresponding indicators of DSTU 3925-99. New experimental data about influence of cast iron chemical composition, modifiers chemical and phase composition, parameters of modifying in precrystallization period process, alloying, cooling rate on structure formation, casting and mechanical properties improvement of ductile cast iron thin-walled products are obtained.