The main structural elements of melts of foundry aluminum‑copper‑silicon alloys are elementary nanocrystals of aluminum, copper, silicon and their free atoms. The main crystallizing phases of these alloys are microcrystals of α‑phases, silicon and θ‑phases. The process of their crystallization is nanostructural. First, structure‑forming nanocrystals are formed from elementary nanocrystals and free atoms. Then the centers of crystallization of microcrystals of phases are formed from them. From them, the structure‑forming nanocrystals of m free atoms of aluminum, copper, and silicon, microcrystals of α‑phases, silicon, and θ‑phases are formed. It is shown that the structural stability during remelting of cast aluminum‑copper‑silicon alloys is inversely proportional to the concentrations of adsorbed hydrogen and oxygen atoms.

A nanostructural mechanism of secondary transformations in the structure of gray cast iron is proposed. First, structureforming nanocrystals of austenite, ferrite, cementite and graphite are formed from elementary nanocrystals of iron and graphite, free atoms of iron and carbon. The crystallization centers of microcrystals of phases are formed from them. From these centers, structure‑forming nanocrystals of phases, free iron and carbon atoms, microcrystals of austenite, ferrite, cementite and graphite of binary gray cast irons are formed.

It is shown that the main modifying intermetallides of primary microcrystals of aluminum alloys do not satisfy the principle of structural and dimensional correspondence. Nonmetallic inclusions and intermetallides cannot be centers of crystallization of metallic melts. These centers are nanostructured formations formed from structure‑forming nanocrystals of crystallizing microcrystals of phases and free atoms of alloy components. Such crystallization centers of metal melts satisfy the principle of structural and dimensional correspondence. The main mechanism of action of casting alloy modifiers is a significant decrease in the concentration of surfactants, which reduce the concentration of crystallization centers of metal melts.

Based on thermodynamic calculations, it is shown that heating and cooling of metals and alloys are reversible, equilibrium processes. Based on thermodynamic calculations, it is shown that melting and crystallization of metals and alloys are also reversible, equilibrium processes. With an increase in the cooling rate of the metal, the temperature of its equilibrium crystallization decreases. At a high rate of metal cooling, a short‑term initial process of nonequilibrium crystallization is observed, which quickly passes into the main stage of equilibrium crystallization.

A nanostructural mechanism for recrystallization of binary aluminum and tin bronzes has been developed. First, structure-forming nanocrystals of α-phases, β-phases and γ-phases are formed from elementary nanocrystals of copper, aluminum, tin and their free atoms. The crystallization centers of microcrystals of phases are formed from them. From these centers, structure-forming nanocrystals of phases, free atoms of copper, aluminum, tin, microcrystals of α-phases, β-phases and γ-phases of binary aluminum and tin bronzes are formed.

A nanostructural mechanism for recrystallization of carbon steels has been developed. First, structure‑forming nanocrystals of austenite, ferrite and cementite are formed from elementary nanocrystals of iron and graphite, free iron and carbon atoms. The crystallization centers of microcrystals of phases are formed from them. From these centers, structure‑forming nanocrystals of phases, free iron and carbon atoms, microcrystals of austenite, ferrite and cementite of carbon steels are formed.

It is shown that devices in the form of a water‑cooled metal mold with a graphite lining, which is located on the upper surface of the casting close to the end of the crystallizer, can serve as an alternative to secondary water‑air cooling systems in horizontal continuous casting. The effectiveness of the cooling capacity of the molds was evaluated during industrial tests of the devices in the process of casting iron. It has been established that the use of water‑cooled molds allows reducing the surface temperature at vulnerable points of the casting by 20–70 °C, increasing the average casting speed for individual billet sizes within 5–8 % almost eliminating shell breakout and eliminating the need for traditional secondary cooling systems.

It has been shown that the effect of structural inheritance in casting eutectic cast irons can be explained from the standpoint of nanostructured crystallization of foundry alloys. Proposed is a mechanism of structural heredity when casting eutectic cast irons. This mechanism is determined by the stability of the crystallization centers of microcrystals of austenite, graphite, cementite. This stability has been shown to depend on the concentration of adsorbed oxygen atoms. The higher this concentration, the less stable the centers of crystallization of microcrystals of austenite, graphite, cementite in melts of eutectic cast irons, and vice versa. With an increase in overheating and (or) the holding time of melts, the concentration of adsorbed oxygen atoms in them increases. As a result, structural stability during remelting of eutectic cast irons is reduced and the effect of structural heredity is disturbed.

A nanostructural mechanism of structural stability during remelting of foundry binary alloys has been developed. This mechanism is determined by the stability of the centers of crystallization of microcrystals of α‑phases and β‑phases. It is shown that this stability depends on the concentration of adsorbed hydrogen and oxygen atoms. The higher these concentrations, the less stable the centers of crystallization of α‑phase and β‑phase microcrystals in melts of foundry binary alloys, and vice versa. With an increase in overheating and (or) the holding time of melts of foundry binary alloys, the concentrations of adsorbed hydrogen and oxygen atoms in them increase. As a result, structural stability decreases during the remelting of foundry binary alloys.

It is shown that hydrogen atoms in carbon steel melts are surface‑active elements for aluminum oxide microcrystals. Adsorbed hydrogen atoms reduce the interfacial surface energy and increase the resistance of small aluminum oxide microcrystals to coagulation. To reduce their stability in liquid carbon steels, it is necessary to reduce the concentration of dissolved hydrogen in them. Active modifiers reduce the concentration of adsorbed hydrogen. This enhances the process of coagulation of small microcrystals of aluminum oxide into larger particles that can quickly float in the melt.

It is shown that hydrogen is a demodifying element of primary structures of tin and aluminum bronzes during their crystallization. The mechanism of influence of hydrogen on the formation of primary structures of tin and aluminum bronzes can be explained from the position of nanostructured crystallization of casting alloys. Hydrogen atoms adsorbed on elementary nanocrystals in melts prevent the combination of nanocrystals into nuclei of crystallization of microcrystals α‑phases of tin and aluminum bronzes. The result is castings with unmodified primary structures. The modifiers reduce the concentration of adsorbed hydrogen in the melts of tin and aluminum bronzes. This results in the milling of the primary phase microcrystals in the castings as they solidify.

It has been shown that hydrogen and oxygen atoms cannot be present in the open pores of crystal lattices of base metals of casting alloys. The solubility of gases in liquid casting alloys is a nanostructured process. Hydrogen and oxygen atoms in melts are adsorbed by basic metal elemental nanocrystals. Nitrogen dissolves in liquid iron, nickel and chromium not in atomic form, but in the composition of elementary nanocrystals and nitride molecules. After deoxidation of molten casting alloys, the main gas dissolved in them is hydrogen.

It has been shown that elementary crystal lattices of basic phases and oxides of casting alloys do not satisfy the principle of structural and dimensional correspondence. Formation of crystallization centers during solidification of casting alloys is a nanostructured process. The main demodifying element in melt crystallization is adsorbed hydrogen. It prevents the integration of nanocrystals into the nucleus of crystallization of the main phases of casting alloys. When the melt overheats, adsorption and desorption of hydrogen atoms occur. The predominance of one of these processes explains the features of crystallization of cast‑ ingalloys. Prior to critical superheating of the melt, the adsorption of hydrogen atoms prevails. As a result, molds with an unmodified structure are formed. When the melt overheats above the critical one, the process of desorption of hydrogen atoms prevails. As a result, molds with a modified structure are formed.

It is shown that eutectoid reactions of binary alloys are nanostructural processes. The main phase, which decays during the eutectoid reaction, is formed during the crystallization of a metal melt of eutectoid composition. This process is nanostructured. In it, the main elements of microcrystals are the nanocrystals of the alloy components. During the eutectoid reaction, the microcrystals of the main phase disintegrate into nanocrystals. Microcrystals of the other two phases are formed from them.

It has been shown that the elementary crystal cells of the basic products of deoxidation and modification of carbon steel, δ ferrite and austenite do not correspond to the principle of structural and dimensional correspondence of Dankov – Konobeevsky. Modifying elements Ba, Ca, Mg, Ce, Al increase the surface energy of the iron‑carbonaceous melt by binding surface active oxygen. Deoxidizers combine dissolved (free) oxygen into oxides, and modifiers – adsorbed oxygen. Steel modification is a nanostructural process in which modifying elements refine elemental iron nanocrystals from adsorbed oxygen and hydrogen atoms. Modifying elements reduce the concentration of dissolved hydrogen, which contributes to the modifying effect. The strongest deoxidizer and modifier of carbon steel is magnesium.

It has been shown that elementary crystalline cells of graphite and basic products of iron modification do not correspond to the principle of structural and dimensional correspondence of Dankov –Konobeevsky. Modifying elements Al, Ca, Mg, Ba, Ce increase the phase tension melt‑graphite by binding surface‑active oxygen and sulfur. Modifying cast iron eutectic graphite is a nanostructured process in which modifying elements refine elemental graphite nanocrystals from adsorbed oxygen and sulfur atoms. This contributes to an increase in the concentration of graphite nuclei upon solidification of the cast iron melt. The modification reduces the concentration of dissolved hydrogen, which increases the effectiveness of the modifying effect. Reduced concentrations of demodifying surface‑active elements, melt degassing, increased heat removal contribute to increasing the degree of branching and compactness of graphite dendrites during iron crystallization. The strongest modifying element of eutectic cast iron graphite is magnesium.

It is shown that the main modifiers of foundry magnesium alloys cannot create heterogeneous crystallization centers in melts during their solidification. Modification of alloy structures is an adsorption‑nanostructural process. It is shown that adsorbed hydrogen is a modifying element of the structures of foundry magnesium alloys. The mechanism of their modification consists in a large decrease in the concentration of adsorbed hydrogen in melts by significantly reducing the concentration of dissolved hydrogen.

It has been shown that elementary crystalline cells of α‑phases of tin, aluminum bronzes and main modifying phases do not correspond to the principle of structural and dimensional correspondence of Dankov‑Konobeevsky. Modifying structures in tin and aluminum bronze castings is a nanostructured process. The main role of tin and aluminum bronze modifiers is to significantly reduce the concentration of adsorbed hydrogen, which prevents the formation of crystallization centers of α‑phase microcrystals in castings when they solidify.

It is shown that the open pores of the crystal lattices of iron, manganese, titanium, cobalt cannot contain hydrogen, oxygen, nitrogen and carbon atoms. In solid solutions of alloys, hydrogen and oxygen atoms are present in the adsorbed state. Nitrogen atoms are mainly included in metal nitrides. Carbon atoms are found in elementary graphite nanocrystals. In solid solutions of alloys consisting of metals, their atoms are part of nanocrystals. They mainly consist of metal alloys. The formation of solid solutions of alloys is a nanostructural process.

An analysis of the state of foundry production in the world is presented, as well as an analysis of the state of foundry production in the Republic of Belarus. The dynamics of changes in production capacities, the degree of loading and the volume of production of castings for various types of alloys is shown. It is established that the structure of cast products produced both in the world and in the Republic of Belarus is in constant dynamics and there is a constant change in the ratio of production volumes from various alloys. The development of the foundry production of the Republic of Belarus as a whole is similar to the world foundry production, however, there is a certain time lag and certain differences in the ratio for different types of casting.