Karlikova Y. Improvement of mechanical properties and the structure of rolled plates, made of continuously cast steel by complex microalloying.

The object of investigation -the processes of structure formation at complex micro-alloying and their impact upon the mechanical properties. The objective was further expansion of knowledge, regarding the impact of complex micro-alloying upon the formation of structure and properties of steel, optimization of micro-alloying process and drastic improvement, on its basis, of chemical, physical structure-dependant properties of the entire rolled heavy plate and in the axial zone, particularly. The innovation of the work lies in the fact that the possibility was found out to increase plasticity and yield strength of steel in case of its micro-alloying with V, Nb and Ti, by means of prevention of formation of carbon-nitride films alongside the grain boundaries. Also described was the origin and the cause of low plasticity value of rolled stock, manufactured of continuously cast steel in Z-direction; prescribed was the opportunity of control over the formation of structure inside the axial zone of rolled stock, by means of complex micro-alloying with V, Nb, Ti and alkaline and rare-earth elements; the way to increase corrosion resistance of continuously cast steel was discovered, as well as the possibility of diminishing the negative impact of non-ferrous metal admixtures upon the rolled stock quality, by micro-alloying with Fe-Si-Ca-Ce-alloy system. The degree of implementation -the proposed micro-alloys were implemented at the converter shop of "Azovstal iron and steel works" PJSC, resulting in estimated economic effect, amounting to 513 thousand of hryvnas. The sphere of utilization -iron and steel industry (converter production of steel).