Parkhomchuk Z. The structure and properties of steels, modified by dispersion-structure components of the charge.

The thesis is dedicated to the development of scientific and technological bases of purposeful influence on the formation of structure and properties of steel castings from carbon and alloyed steels by hereditary modifications using charge components and modifiers with fine prepared nonequilibrium structure. It was shown that introduction into the melt of dispersion-structured additives of steels of similar chemical composition (15 - 20%), which have been rapidly crystallized facilitates the formation of a significant number of additional nucleation centres and implementation of the mechanism of hereditary modification. This improves the strength characteristics of steel of 10-15 %; 1,5 - 2-times increase in ductility, toughness by 30 - 40 % compared with the properties of unmodified steels. This paper shows promising application as modifiers of hereditary modification steel granules and powders got at rapid cooling crystallization and after hardening and deformation-thermal treatment. All the proposed modification improves characteristics of dendrite structure, grain structure, reduce liquation, and increase the level of the mechanical properties of steels. For the first time it is investigated and shown that modifiers (СИИТМиш-3, СК-30) prepared by rapid crystallization with fine structure and nanosized inoculators (SiO2, SiC) developed as part of the aluminum based ligature are effective for the crystallization, structure formation and properties of steels.