卷 49, 编号 11 (2019)

Fe–Cu alloys can be characterized as a system with immiscible components (IC). This statement is based on a weak mutual solubility in the solid state. In addition, Fe–Cu system stratifies in the liquid state at low carbon content. Alloys with ICs have a simple phase composition of almost pure components, which determines a significant practical interest in these alloys. Manufacturers have technologically succeeded in achieving damping alloys of Fe–Cu–Pb system. With proper technological preparation, the final product can be obtained by combining the properties of pure alloy components in the fraction required for practical application. For example, diamagnetic copper has high electrical conductivity and thermal conductivity in Fe–Cu alloys, while ferromagnetic iron has enhanced strength characteristics compared to copper. When the alloy structure is organized in a certain way, a final product can be obtained with high electrical conductivity and thermal conductivity of copper, enhanced strength properties of iron, or a hard magnetic material with copper ductility. The studies of iron-copper alloys focused on the structural studies and measurements of service properties. At the same time, the dynamics of macro- and microstructure alloy formation were not analyzed. In the present studies, the macrostructure formation dynamics of the solid phase enriched with iron at the crystallization melt process during cooling was studied using high-temperature viscometry. Due to the effect of the melt-cooling rate on the size and morphology of crystallizing inclusions, as well as a significant amount of the two-phase area, special attention was paid to the thermophysical analysis of the measurement mode. Analysis of the reliability of the results obtained was made by the viscosity measurement method. The phase state of Fe–Cu system melts was investigated during cooling by changing the damping factor. The analysis of thermophysical processes occurring during measuring the damping factor was carried out. The measuring process of damping decrement takes place under quasi-equilibrium conditions and the cooling rate is close to zero. There are no temperature gradients, both in radius and in height. For compositions Fe₅₀Cu₅₀, Fe₄₀Cu₆₀, and Fe₃₀Cu₇₀, the precipitation dynamics of the solid phase was determined.

Ni–Co alloys are broadly used in various industries. One of the harmful impurities in these alloys is oxygen, which is found in metals in dissolved form or as nonmetallic inclusions. One of the main tasks of melting out these alloys is to produce a ready-made metal with a minimal oxygen concentration. In the case of the metal melt’s complex deoxidation, the activities of oxides formed by deoxidation are below one. This allows metal production with a lower oxygen concentration and, therefore, is more deeply deoxidized at the same deoxidizing element content. The dominant role in the joint deoxidation with two deoxidants is played out by the stronger of the two. However, if the oxides of the deoxidizing elements form chemical compounds, the weaker deoxidant in deoxidation will stand out. The joint influence of aluminum and silicon on the oxygen solubility in Ni-Co melts is exposed to thermodynamic analysis. The compounds that can form in deoxidation products include both, mullite (3Al₂O₃ ⋅ 2SiO₂) and kyanite (Al₂O₃ ⋅ SiO₂). Silicon presence in the melt slightly enhances the deoxidizing ability of aluminum for the formation 3Al₂O₃ ⋅ 2SiO₂ and significantly for the formation of Al₂O₃ ⋅ SiO₂. The oxygen solubility curves for the formation of Al₂O₃ ⋅ SiO₂ pass through the minimum point in which the position depends on the melt’s aluminum content and does not depend on the silicon content. As in the case of Ni–Co–Al melts, the aluminum content in the minimum points slightly go down from Ni to Co. Further aluminum additives increase the oxygen concentration. The article determines the regions, where Al₂O₃, 3Al₂O₃ ⋅ 2SiO₂, Al₂O₃ ⋅ SiO₂, and SiO₂ are formed due to the aluminum and silicon content in the melt. The deoxidizing ability of aluminum and silicon in Ni–Co alloys become enhanced with increasing cobalt content in the melt; however, the higher is the cobalt content in the melt, the lesser is the extent to which silicon enhances the deoxidizing ability of aluminum.

This study focuses on the laboratory metal’s cold resistance of a new austenitic nitrogen-containing (21–22) Cr–15Mn–8Ni–1.5Mo–V casting steel (Russian grade 05Kh21AG15N8MFL) with a nitrogen content of 0.5% and a yield strength of ~400 MPa. The temperature relation of impact viscosity was constructed for this steel in a range from +20 to –160°C, the steel appeared to have a broad range of ductile-brittle transition temperatures with commercial, centrifugally cast 18Cr–10Ni steel (grade 12Kh18N10-CC), and it reached this KCV at 20°C. It is not prone to ductile-brittle transition, its impact strength decreases more smoothly at T < –80°C, and its KCV is higher than that of nitrous steel. However, its impact viscosity exceeds in the entire climatic temperature range by nitrous cast steel with 0.5% of N. The tested steels have residual δ-ferrite in the cast structure—up to 10% in Cr–Ni industrial steel and a smaller amount in laboratory nitrous steel. This ferrite is enriched with chromium up to 26 and 34 wt %, respectively, and contains ~14% of Mn in nitrogen steel. The Mn presence does not affect its type of fracture at climatic temperatures. However, at ‒160°C, the δ-ferrite of nitrous steel is beyond the cold brittle threshold. Therefore, its fracture obtained at this temperature contains numerous cracks in δ-ferrite crystals. When critical brittleness temperature is T_cr ≈ –110°C, this material is not recommended for use, as recommended by the criterion technique. It corresponds to KCV of 68 to 83 J/cm², higher than KCV allowed by Russian standards for austenitic steel casts at 20°C (up to 59 J/cm²). According to current literature and new research, the corrosion-resistant steel existing with nickel cannot have high cold-resistance and, at the same time, high strength by alloying it with 0.5 to 0.6% of nitrogen.

This paper proposes to improve the durability of the heat insulating insert for the air passage of the blast furnace tuyere by applying a slurry coating to the tuyere’s inner surface. In addition, the tuyere installation variant after assembling and exposing it to hydraulic tests is considered, as well as heat loss reduction by attaching refractory fabric to the tuyere nose. The slurry coating applied to the insert’s inner surface has made it more durable by at least 30%. Theoretically, the insert can be made more durable when installed in the air passage after assembling the tuyere and exposing it to hydraulic tests. Studies have shown that the heat losses can be reduced by 10% on average by using refractory siliciferous fabric to ensure the heat insulation of the tuyere nose.

The computer-simulated normal stress distribution in the working zone of the draw die and the dependence of its magnitude on various drawing parameters is given. Derived from the data and previously developed procedures for the evaluation of the metal’s stress state in the deformation zone, the operative wire drawing sequence is analyzed and improved, which is focused on subsequent quenching and tempering. The industrial experiment results confirm the performance of the new drawing sequence during the fabrication of thermal-treated spring wire.

The electro-mechanical treatment (EMT) technology of steels is considered. The regularities of hardening treatment modes, in particular of the current density when EMT is established and optimized, provide an ideal surface layer quality and increase the friction surface’s wear resistance. The parameters of the surface layer quality after electro-mechanical hardening were studied. The tribotechnical tests were carried out in order to compare with wear-resistant coatings fabricated by traditional treatment methods.

Dilatometric studies on medium-carbon Cr–Mn–Mo 40KhGMA steel with various chemical compositions are performed. Thermokinetic diagrams for the transformation of supercooled austenite are plotted, and the temperature-time ranges for the formation of structural components are determined. The metallographic study of the steel microstructure have been carried out after cooling at different rates. Steel hardness depending on the tempering temperature and mechanical properties in the heat-treated state are studied. By using a numerical simulation, cooling paths under heat treatment have been determined for a drill pipe with a wall thickness of 30 mm.