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Abstract  The common features of lengthwise rolling, cross rolling, and screw rolling (which is the most general case) are found. A mathematical model is used to obtain the values of velocity coefficients at any point in the deformation zone, to reveal the position of the neutral line and the conditions affecting the relation between forward and backward creep zones, and to find the cases where a forward creep zone is absent.

Abstract  The machinability of the high-nitrogen corrosion-resistant austenitic steel 06Kh22AG15N8M2F during turning is studied. The specific features of the structure of the surface layers in steel workpieces after turning are revealed. The cutting conditions that provide the lowest wear of VK8 alloy cutting tools upon turning are found: the cutting speed is 21–74 m/min, the feed is 0.15–0.60 mm/rev, and the cutting depth is 0.15–0.75 mm. The presence of a large amount of Cr₂N-type chromium nitrides in the structure of the steel annealed at 800°C for 2 h and a high nitrogen content in the austenite of the steel quenched from 1100°C increase the wear of the cutting tools. As to turning of the forged steel, the wear resistance of the cutting tools upon turning of the 06Kh22AG15N8M2F steel is higher than that upon turning of 08Kh18N10T steel, in which deformation martensite forms (in surface layers) during turning.

Abstract  The phase formation and kinetics of metal reduction upon the interaction of natural iron-manganese tantalum niobates with carbon is studied using X-ray diffraction analysis, electron probe microanalysis, and thermogravimetry. The reducibility of the minerals increases in the series wodginite-tantalite-columbite. Reduction occurs in stages with the formation of niobium tapiolite and disordered tantalite and wodginite as intermediate phases.

Abstract  A process is developed for the autoclave leaching of nickel and manganese with sulfuric acid from the products of catalytic synthesis of industrial diamonds containing 20% Ni and 30% Mn. The optimum conditions for the autoclave processes are determined to be as follows: the temperature range is 150–160°C, the solution acidity is 5 N H₂SO₄ (230–240 g/l), the leaching duration is 2 h, and the number of processing steps is two. The extraction of the metals into a solution under these conditions is >99% for a total Ni + Co content of <0.4–0.5% in the autoclave leaching cake. The studies performed are related to the search for alternative ways of the catalytic preparation of industrial diamonds that can replace the nonferrous metal leaching technology using aqua regia solutions, which is mainly applied for these purposes under industrial conditions.

Abstract  High-temperature mass-spectrometric analysis is used to study the sublimation of SrMoO_4(s) at 1570–1800 K. SrMoO_4(g) molecules are found to be present in the vapor. The vapor pressure of the SrMoO_4(g) molecule is determined to be log p = −19980/T + 7.99. The heat of sublimation ΔH _{s, 0}^o (SrMoO_4(s)) = 480 ± 40 kJ/mol is determined using the third law of thermodynamics. The atomization energy of the SrMoO_4(g) molecules is calculated to be ΔH _{at, 0}^o (SrMoO_4(g)) = 2860 ± 40 kJ/mol.

Abstract  The interaction of a surface with the two-phase flow of a multicomponent vacuum-arc plasma containing droplets of an evaporated material along with multicharged ions and neutral atoms is studied. For the two-phase flow of a multicomponent plasma, the dependences of the ion-current density, the deposition rate, and the heat flow to a substrate on the bias voltage are obtained, and the conditions at which the coating deposition rate is inverted are determined. A unique probe technique for the plasma flow generated by an end-face Hall plasma accelerator with a “cold” eroded cathode is used to determine the volt-equivalent energy U** of the interaction of the two-phase plasma flows of Ti, Al, Cr, and an Ni-Cr-Al-Y alloy with a surface and the self-sputtering coefficient of the Ni-Cr-Al-Y alloy and its elements (Ni, Cr, Al) as a function of the bias voltage. Metallographic analysis is used to study the structure of thick (∼100-μm) coatings deposited from the two-phase flow of a metallic multicomponent vacuum-arc plasma.

Abstract  The compositions of the calcium aluminosilicatoferrite phases in commercial iron-ore sinters, which are solid solutions based on CaFe₄O₇, CaFe₂O₄, and Ca₂Fe₂O₅ ferrites of the CaO-Fe₂O₃ system, are studied. The sequence of the formation of the calcium aluminosilicatoferrites and their compositions with Ca₂SiO₄ and Ca₃SiO₅ silicates in sinters is found to be analogous to the crystallization of the ferrite and silicate phases in the ternary CaO-SiO₂-Fe₂O₃ system. This allows the phase diagram of this system to be used for the explanation of the formation of the mineral binder compositions for ore grains during sintering of commercial superfluxed sinters.

Abstract  A technique is developed for the correction of the depth distribution of residual stresses measured by an X-ray method with allowance for their relaxation upon the removal of surface layers. This technique is applied to the study of a D16 aluminum alloy strip subjected to shot-blasting metal forming. This technique can be used to estimate the distribution of residual stresses across massive parts after various types of treatment.

Abstract  The effect of the concentration of preliminarily introduced hydrogen on the creep and long-term strength of VT6 (Ti-6Al-4V) titanium alloy is studied experimentally and theoretically at a temperature of 600°C and nominal stresses of 47–217 MPa. Tests show that the presence of hydrogen in the titanium alloy (to 0.3 wt %) increases the time to failure and decreases the steady-state-creep rate and the ultimate strain by several times. A kinetic theory is used to simulate creep up to failure. The specific features of the macroscopic characteristics of creep are studied along with the evolution of the structural state of the alloy.

Abstract  The viscoplastic model of the strain resistance of a metal developed earlier is shown to be applied to austenitic corrosion-resistant 08Kh18N10T steel with the fcc lattice at a hot-deformation temperature of 1150°C. Metallographic examination supports dynamic recrystallization occurring at this deformation temperature.

Abstract  The effect of silicon on the operational efficiency and corrosion resistance of low-temperature equipment made of 12Kh18N12T chromium-nickel steel has been studied. The specific features of the cryogenic equipment consist in high-temperature heating procedures between operation periods. Equipment for gas liquefaction and cleaning aimed at the restoration of the operational efficiency of filtration and catalysis systems serves as an example. The heating temperature of this equipment can reach 800°C. Experimental steels containing 0.09–1.03 wt % Si are subjected to intercrystalline corrosion tests. Upon heating to 550–600°C, silicon is found to increase the corrosion resistance of the steel, and, upon heating at higher temperatures, silicon plays a negative role. This is caused by the distribution of silicon atoms along grain boundaries, namely, a nonuniform silicon distribution with the formation of high-and low-concentration regions, i.e., the formation of clusters of silicon-phase preprecipitates.

Abstract  The structure and hot hardness (at temperatures up to 1100°C) of RuAl-based powder alloys with 1–3 at % Ni, Mo, Re, or Ru are studied. The alloys are produced by the reactive sintering of cold-compacted bars and subsequent threefold isostatic pressing with intermediate annealing at 1500°C performed after the first hot isostatic pressing. The samples have a residual pore content of 1–2.5 vol % and are characterized by a micrononuniform distribution of base and alloying elements. The alloys with refractory metals, such as Re, Mo, or Ru, are found to have the maximum hardness at all temperatures under study. At low temperatures, the effect is more substantial; the hardness of the Re-containing alloys exceeds that of the other alloys by a factor of 1.3–3.6. The increase in the hardness related to solid-solution alloying becomes more substantial owing to the microinhomogeneity of the sintered powder alloys and weakens because of microporosity. Recommendations that allow the uniformity of the distribution of the base and alloying elements to be increased are given.

Abstract  A stack of alternating 25 100-μ-thick Ni₃Al plates and 28 200-μm-thick Mo plates is subjected to hot isostatic pressing (HIP) at a temperature T = 1200°C and a pressure P = 150 MPa for τ = 2.5 h followed by hot rolling at 1050–950°C to a thickness of 2.3 mm. The stack is then subjected to cold rolling (CR) to a thickness of 0.5 mm without intermediate annealing, subsequent annealing during HIP at T = 1200°C, P = 150 MPa, and τ = 2.5 h, and CR to a thickness of 0.22 mm. Upon CR at a strain ε changing from 80.8 to 95.8%, the following specific structure forms in the longitudinal direction: molybdenum layers acquire a wavelike structure, can contact with each other, form “cells,” and retain almost the same thickness, and Ni₃Al alloy layers are rejected between the molybdenum layers to form a regular structure made of alternating thickenings and thinnings across the rolling direction. Annealing during HIP and subsequent CR to ε = 98.2% lead to the formation of zones with a broken alternation of layers in the longitudinal and transverse directions, which is related to different strain resistances of the (more refractory) molybdenum and Ni₃Al layers at 20°C. The adhesion between the layers is good, and no intermediate phases form at the interface. The ultimate bending strength of the 2.3-mm-thick workpiece at 20°C is 1000 ± 100 MPa, and the prepared material has a plasticity margin.

Abstract  The possibility of the determination of the tendency of cast and deformed steels to brittle fracture using the temperature dependence of the small-plastic-strain rate is studied. The temperature corresponding to the maximum in this curve is found to indicate an abrupt decrease in the steel plasticity, which makes it possible to interpret it as the ductile-brittle transition temperature depending only on the structure of a material.

Abstract  Stress-strain and coercive force-strain diagrams are experimentally obtained for grade 45 and St3 steels. These diagrams are used to construct matrix dependences between the elastoplastic and magnetic properties of the steels in order to determine the level of stresses in construction members made of these steels.

Abstract  The thermodynamic properties of silicon-containing cementite and ε carbide are estimated, and the results obtained are used to perform the thermodynamic calculation of paraequilibria in the Fe-Si-C system. Even a relatively low silicon content is shown to substantially change the positions of virtually all boundaries of phase fields in the Fe-C phase diagram. The relation between the paraequilibria and bainite transformation was analyzed. The maximum supersaturation of retained austenite is found to be controlled by a thermodynamic factor, namely, the solubility of the paraequilibrium cementite. The thermodynamic specific features also cause the differences in the mechanisms of carbide precipitation from the α and γ phases in the absence of silicon redistribution: only cementite can precipitate from austenite, whereas both cementite and ε carbide can precipitate from bainitic ferrite.

Abstract  The data on the Ni-Al-R (R = REM Sc, Y, La, lanthanides) binary and ternary systems and the interactions of three rare-earth metals (yttrium, lanthanum, cerium) with the main alloying elements (Ti (Zr, Hf), Cr (Mo, W) that are introduced into Ni₃Al-based VKNA alloys are analyzed. The binary aluminides of REMs in the Ni-Al-R ternary systems are shown to be in equilibrium with neither NiAl nor Ni₃Al. The solid solution of aluminum in RNi₅, which penetrates deep into these ternary systems, is the most stable phase in equilibrium with Ni₃Al. In the NiAl (Ni₃Al)-AE-R systems, REM precipitation (segregation) on various defects and interfaces in nickel aluminides is likely to be the most probable, and REMs are thought to interact with the most active impurities in real alloys (C, O, N), since REMs have a large atomic radius and, thus, are virtually undissolved in nickel, aluminum, and nickel aluminides.

Abstract  The base and weld metal of a liquid-helium pipeline having operated for its projected service life is analyzed. The service risk factors that decrease the operational efficiency of the equipment are revealed. Samples cut from the pipeline are used to model various cryogenic pipeline operation conditions and to show that magnetometric control can be applied to examine low-temperature engineering equipment in order to shorten the time of the engineering inspection of cryogenic equipment and to increase the reliability of the inspection results.

Abstract  The effect of isothermal holdings at 350, 500, 580, 660, and 780°C during heating to various sustenitizing temperatures on the grain size, aging processes, structural and mechanical properties, and the stress-strain curves of 03Kh11N10M2T-VD and 03Kh11N8M2F-VD maraging steels with 0.002% B is studied. X-ray diffraction analysis and metallographic examination are performed, and the corrosion and fatigue characteristics of these steels are determined. At the aged state with the maximum strength, the steels exhibit no strain-hardening ability upon tension and retain a high local plastic deformation during necking (ψ ≤ 60%). Preliminary thermal-cycling treatment at 500–800°C causes grain refinement and increases the plastic properties of the steels (the uniform elongation increases to 20%). Isothermal holding during heating to the austenitizing temperature affects an elastoplastic transition at a low tensile strain.

Abstract  The structure and corrosion properties of two high-nitrogen 05Kh20AN8MF steels additionally alloyed with 9 and 17% Mn have been studied. Metallographic, X-ray diffraction, and fractographic studies show that both steels have an austenitic structure and high plasticity properties after quenching from 1100 and 1100°C and subsequent aging at 500°C for 2 h. The steel alloyed with 9% Mn and 0.58% V exhibit a higher strength. Both steels have a higher corrosion resistance in a 3.5% NaCl aqueous solution than 12Kh18N9T steel. After aging at 400–600°C, the corrosion rate and the sensitivity to stress corrosion cracking increase.