An opportunity of the spectra of conformable structural states in the iron melt, obtained with the different temperature and rate conditions of formation, varied by mutually compensated values of the entropy and viscous flow activation energy, was ascertained by high-temperature viscometry methods. Permanence of the states and conditions of the mutual conversions were researched; two of the most stable states, typical for the cases of low- and high-intensive heating and fusion, conditionally qualified correspondingly as spongy and closely packed by the viscosity level and the value of entropy contribution into free energy of the viscous flow, were separated out. Peculiarities of the structural states of iron solutions with vanadium, silicon and carbon were developed and its relationship with initial structural state of the iron melt was determined. Possibilities of the structural investigations of the melts with thermodynamic parameters of solutions were indicated. Particularly, the summary on non-idealness of the carbon and silicon solutions in iron, as well as vanadium behaviour in such solutions, close to ideal, were con-firmed qualitatively. Correlation of the solid metal properties with the structural state peculiarities of the melts were established and the ways of technological implementation of the steel quality improvement reserves with micro-alloying were outlined. An opportunity of the spectra of conformable structural states in the iron melt was determined for the first time. Differences of the structural states of iron solutions with vanadium, silicon and carbon were developed and its relationship with initial structural state of the iron melt was determined. Possibilities of the structural investigations of the melts with thermodynamic parameters of solutions were indicated. Manufacturing approaches on increasing the quality of steels and alloys were extended.