Metal Science and Heat Treatment

doi: 10.1007/s11041-020-00504-5pmid: N/A

Rudskoy, A. I.; Kolbasnikov, N. G.

doi: 10.1007/s11041-020-00505-4pmid: N/A

Features of the development of digital twins of thermomechanical steel treatment processes and examples of production tasks solved with their use are considered. The technique of creating digital twins of hot rolling, as well as hot or cold rolling with subsequent heat treatment is described. Adistinctive feature of the digital twin being developed is that in addition to the finite-element model of the process, it must also contain an integral model of structure formation that occurs in the treated steel throughout the process.

Chizhik, S. A.; Vityaz, P. A.; Kheifets, M. L.

doi: 10.1007/s11041-020-00506-3pmid: N/A

Systematic analysis of the state and prospects of the development of additive technologies for computer-aided production is conducted to show a new paradigm of their evolution. An approach determining the additive methods as synergy technologies that provide self-organization of surface phenomena is suggested. The new approach is used for choosing the most efficient energy sources and materials for the technologies of layer-by-layer synthesis of articles. It is shown that stabilization of the thickness of the formed layers correlates with the processes of self-organization of surface phenomena and design features of the articles.

Popovich, A. A.

doi: 10.1007/s11041-020-00507-2pmid: N/A

The main directions of the development of additive technologies at the Peter the Great St. Petersburg Polytechnic University are considered. Fabrication and research of spherical powders of complexly alloyed alloys for additive production from metal waste and of functionally graded materials with variable structure, chemical composition and porosity, synthesis of intermetallic titanium alloys by selective laser melting are considered among other examples.

Stroganova, T. S.; Karpov, M. I.; Prokhorov, D. V.; Logacheva, A. I.

doi: 10.1007/s11041-020-00508-1pmid: N/A

The results of creep tests in the bending mode at 1150 – 1200°C for the Nb – Si – X alloy (X = Mo, Ti, Hf, Zr, Cr, Al) after hot isostatic pressing and after induction melting in the mode of directed crystallization are analyzed. It was shown that the creep rate of powder alloys is an order of magnitude higher than the creep rate of an alloy with a directed structure, which is related to the microstructural features of the alloy and the type of silicide formed in its structure. In all the alloys tested, the short-term bending strength at 20°C weakly depends on their composition and method of fabrication, while at 1300°C the alloy with a directed structure has the highest strength.

Mustafaeva, S. N.; Guseinova, K. M.; Asadov, M. M.

doi: 10.1007/s11041-020-00509-0pmid: N/A

Single crystals of (1 – x)TlGaSe2 ∙ xDy (x = 0; 0.01; 0.03) were synthesized. The laws of variation of the dielectric parameters and conductivity of (1 – x)TlGaSe2 ∙ xDy materials are determined as a function of their composition and frequency of the ac electric field. Doping of dysprosium into TlGaSe2 crystal matrix substantially increases the real and imaginary components of the complex dielectric permittivity, the dissipation factor, and ac conductivity.

Kondrat’ev, S. Yu.; Petrov, S. N.; Anastasiadi, G. P.; Tsemenko, A. V.

doi: 10.1007/s11041-020-00510-7pmid: N/A

Optical and electron microscopy, x-ray spectral microanalysis, and thermogravimetric analysis in combination with differential scanning calorimetry are used to study the high-temperature oxidation behavior of alloy HP40NbTi of the Fe – 25Cr – 35Ni system prepared by static and centrifugal casting, and also oxidation process kinetics. It is shown that high-temperature oxidation of refractory alloy HP40NbTi is a complex physicochemical process that apart from temperature and time of the process is determined by the degree of alloy structure fineness.

Kondrat’ev, S. Yu.; Petrov, S. N.; Anastasiadi, G. P.; Tsemenko, A. V.

doi: 10.1007/s11041-020-00511-6pmid: N/A

Optical and electron microscopy and x-ray spectral microanalysis are used to study the transformation of the phases present in the structure of cast refractory alloy HP40NbTi during prolonged high-temperature oxidation. It is established that during oxidation alloy phase chemical composition changes continuously and by complex laws in relation to the surroundings, temperature, and exposure duration, and there is rapid exchange of chemical elements between different phases. After prolonged exposure this process reaches a limiting condition.

Platov, S. I.; Krasnov, M. L.; Urtsev, N. V.; Danilov, S. V.; Lobanov, M. L.

doi: 10.1007/s11041-020-00512-5pmid: N/A

Orientation microscopy (EBSD) is used to study structural and textural states through the thickness of pipe steel strips after a controlled thermomechanical treatment. It is shown that texture formation in the form of a selection of components (3 – 7) with a large number of versions of crystallographic orientations, arising with shear phase transformations in accordance with the orientation ratios, suggests presence within the steel structure of elements limiting the number of possible α′-phase orientations. It is proposed that these elements are special boundaries formed during hot rolling close to boundaries RSU Σ3 and Σ11 between deformed austenite grains.

Makarov, A. V.; Savrai, R. A.; Skorynina, P. A.; Volkova, E. G.

doi: 10.1007/s11041-020-00513-4pmid: N/A

Results are provided for studying deformation methods of steel surface nanostructuring and hardening with martensitic, pearlitic and austenitic structures. A new method of ultrasonic impact-friction treatment is considered. Combined methods of nanostructuring treatment (friction treatment + annealing) are proposed for a metastable Cr – Ni steel. The possibility is demonstrated of activating steel saturation with nitrogen during plasma treatment due to preliminary nanostructuring friction treatment.