The formation of melts is considered at the structural level on the basis of viscosimetry. The equilibrium and stability of melts in the course of melting, alloying, and microalloying are considered. Data regarding the interrelated properties of liquid and solid metals indicate the possibility of significantly improving the mechanical and corrosion properties of steel on the basis of metallurgical measures that affect the melt structure prior to solidification. Industrial tests show the great significance of such measures in producing impurity-free steel.