Showing papers in "Materials Science in 2016"

Development and Prospects of the Application of Syntactic Foam Plastics as Heat-Shielding Materials in Space-Rocket Technologies

Abstract: We present information on the development and operating properties of NTZP-U syntactic foam plastics based on polyurethane aqueous dispersions, glass, and polymeric microspheres and the data on the thermal properties and durability of the developed heat-shielding materials under the conditions modeling the in-flight temperature conditions formed on the surface of the coating of the nose cone of a “DNEPR” launch vehicle.

Effect of the Velocity of Rotation in the Process of Vibration Grinding on the Surface State

Abstract: We consider one of the processes of surface mechanical attrition treatment, namely, the technique of vibration grinding. It is based on causing surface plastic deformation in the treated part by bombarding it with flexible granular particles. This process is useful and reliable when high surface quality is required. The present work focuses on the effect of velocity on the outcomes of the centrifugal rotational process. Two aspects are considered, namely, the surface roughness and the surface hardness after treatment. Both the mathematical model and obtained experimental results demonstrate the dependence of these two aspects on the velocity of rotation of the chamber. Note that the hardness increases with the velocity of rotation while the effect of the velocity on the surface roughness is negative.

Study of the Mechanism of Action of the Isopropanol Extract of Rapeseed Oil Cake on the Atmospheric Corrosion of Copper

Abstract: The results of gravimetric and electrochemical polarization investigations demonstrate that the isopropanol extract of rapeseed oil cake can be used as an efficient volatile inhibitor of the atmospheric corrosion of copper. The efficiency of action of the surface film in the course of its formation depends on the composition of the gas-vapor phase and, under the conditions of wetting of the metal surface, the corrosion rate is determined by the rate of the cathodic process of reduction of the atmospheric oxygen. In estimating the adsorption activity of organic molecules according to the indices of reactivity and in studying the morphology of specimen surface, we assume that the efficiency of action of the isopropanol extract in the initial stage is caused by the chemisorption of volatile organic components of the rapeseed oil cake, which then interact with each other and transform into surface phase films containing copper ions, water, and organic substances.

Functional Properties of Fe−Mo and Fe−Mo−W Galvanic Alloys

Abstract: The influence of the modes of electrodeposition on the morphology, topography, and structure of the galvanic alloys of iron with molybdenum and tungsten is discussed. It is shown that the increase in the corrosion resistance of Fe–Mo and Fe–Mo–W coatings in acid and neutral chloride-containing media is caused both by the elevation of their passivating ability caused by the process of alloying components and by the formation of globular surfaces with homogeneous chemical composition. The microhardnesses of Fe–Mo and Fe–Mo–W galvanic alloys prove to be 2–3 times higher than the microhardnesses of the substrates made of low-alloy steel, which can be explained by the formation of amorphous structures. The results of investigations and tribological tests show that it is reasonable to apply the coatings of double and triple iron alloys in order to reduce wear in friction couples and to increase the corrosion resistance and mechanical strength of the surfaces, which makes them promising for the repair and restoration technologies.

Diagnostics of Hydrogen Macrodelamination in the Wall of a Bent Pipe in the System of Gas Mains

Abstract: We study the intense hydrogen-induced delamination in the wall of a bent branch pipe after long-term operation at the gas-compressor station of the system of gas mains. The factors playing the key role in the formation of this delamination are analyzed. It is shown that the abnormal readings of a thickness meter and a sharp decrease in the hardness and plasticity of steel are the diagnostic signs of this phenomenon. It was discovered that the degree of degradation of steel of the pipe bent is higher as compared with the straight section of the pipe regardless of their tension or compression. We establish the limitations for the use of the relative elongation and relative narrowing as characteristics of plasticity for the metal of the pipe wall with intense delamination.

Wear Resistance of VT22 Titanium Alloy After Nitriding Combined with Heat Treatment

Abstract: We study the influence of the modes of nitriding combined with standard heat treatment on the wear resistance of VT22 titanium alloy. It is shown that the saturation of nitrogen at a temperature of 750°C for 3 h in the second stage of the standard procedure of heat treatment of the alloy leads to a decrease in its hardness and an improvement of the quality of the surface hardened layer, which guarantees higher triboengineering characteristics of the friction couple with BrAZhN-10-4-4 bronze than in the case of saturation at 820°C, 1 h + 750°C, 3 h in the first and second stages of the standard heat treatment.

Evaluation of the Influence of Hydrogen on the Mechanical Characteristics of Complexly Alloyed Nickel Alloys

Abstract: We study the influence of hydrogen under a pressure of up to 30 MPa with contents of up to 20 wppm on the strength, plasticity, low-cycle fatigue, and short- and long-term crack-growth resistances of five modifications of Ni56Cr17Mo6Nb4 alloy (KhN56MBYuD) (EK-62), which differ by the methods of metallurgical remelting, chemical compositions, and modes of heat treatment. It is shown that the fracture toughness in air and in hydrogen decrease as the grain size decreases and the yield strength and HRC hardness increase, which enables us to predict the changes in the crack resistance according to the data of hardness measurements of the surfaces of workpieces operating in hydrogen. The optimal combination of high strength, plasticity, and short- and long-term crack-growth resistances in air and in hydrogen is attained for the modification alloyed with boron (0.005 wt.%) and zirconium (0.044 wt.%). In the tests for long-term crack-growth-resistance carried out for 100 h, we established the invariant characteristics of crack-growth resistance, namely the threshold values of K IHST varying from 15 to 35 MPa∙m1/2 for different modifications of the alloy.

Nanocomposites of Polypropylene/Nano Titanium Dioxide: Effect of Loading Rates of Nano Titanium Dioxide

Abstract: TiO 2 filled Polypropylene (PP) nanocomposites were prepared with a single screw extruder and then by injection molding of the blends. Water absorption, density, mechanical properties, morphological characterization, FTIR analysis, and the thermal stabilities of the nanocomposites were investigated. The results showed that water absorption decreased and density increased as the amount of nano-TiO 2 added increased. The mechanical properties improved for all formulations with the addition of nano-TiO 2 , except for the tensile modulus of elasticity and the izod impact strength. Thermogravimetric analysis (TGA) indicated that the thermal stability of the nanocomposites improved as the amount of nano-TiO 2 increased. The melting and decomposition peaks of DTA increased as nano-TiO 2 was added. The differential scanning calorimetry (DSC) results showed that the melting temperature ( Tm ) increased with the addition of nano-TiO 2 . Scanning electron microscopy (SEM) images of the nanocomposites showed uniform dispersion for 0.5, 1, and 2 % TiO 2 , but some agglomerations were found on the surfaces and in the fractured sides of the nanocomposites with 4 % TiO 2 . The agglomerates were determined by SEM mapping. The changes in the chemical structure of the nanocomposites were determined with Fourier transform infrared (FTIR) spectroscopic analysis. The FTIR results showed that the chemical structures of the composites were similar and that there were no major differences between the composites. DOI: http://dx.doi.org/10.5755/j01.ms.22.3.8217

Optimization of the Chromium Content of Powder Wires of the Fe–Cr–C and Fe–Cr–B Systems According to the Corrosion Resistance of Electric-Arc Coatings

Abstract: We study electric-arc coatings of the Fe–Cr–C and Fe–Cr–B systems. It is shown that chromium content of 12 wt.% is insufficient to guarantee higher corrosion resistance of the coatings in neutral aqueous solutions (as compared with steels) caused by the formation of chromium-based oxides, carbides, and borides. Therefore, the indicated chromium content of the compounds should be taken into account and compensated in finding the chemical composition of powder wires. Its unjustified increase is not reasonable because powder wires are characterized by filling coefficients restricting the possibility of their filling with alloying elements. Therefore, the content of each alloying element in the charge of powder wires should be well justified and determined. For this purpose, we propose to use the relations taking into account the nonlinear distribution of chromium in the lamellas of the coatings caused by their high microheterogeneity and the depletion of their solid solution of the indicated element as a result of the formation of oxides, carbides, and borides on its base.

Effect of TiB2 Additives on Wear Behavior of NiCrBSi-Based Plasma-Sprayed Coatings

Abstract: The influence of titanium diboride additives on microstructure and wear-resistance of NiCrBSi thermally sprayed coatings deposited on a steel substrate has been studied. NiCrBSi-based composite powders with 10, 20, 40 wt.% TiB 2 particles content were produced. The structure of NiCrSiB-TiB 2 coatings consists of TiB 2 and CrB grains distributed in Ni-based matrix. The wear-resistance of NiCrSiB-TiB 2 plasma sprayed coatings in dry sliding conditions against the same coating using pin-on-disk tester. It was determined that the amount of titanium diboride particles in NiCrBSi-based coatings influences essentially on the wear resistance and wear mechanism. The NiCrBSi-based plasma sprayed coatings containing 20 wt. % of TiB 2 possess the highest wear resistance due to the realization of mechano-oxidational wear mechanism. DOI: http://dx.doi.org/10.5755/j01.ms.22.1.7307

Influence of the Metal Surface of Powder Filler on the Structure and Properties of Composite Materials Based on the Copolymers of Methacrylates with Polyvinylpyrrolidone

Abstract: We study specific features of the formation of structures of metal-filled composites based on the copolymers of 2-hydroxyethyl methacrylate with polyvinylpyrrolidone depending on the composition of the initial mixture and nature and content of the metal. It is discovered that metal powders introduced in a polymer play the role of additional points of cross-linking and promote the formation of more cross-linked structures. It is experimentally demonstrated that a polymer network formed in the presence of metal particles is characterized by different compositions in the interface layers on the surfaces of metal particle and in the bulk of the polymer. We also establish the relationship between the physicomechanical properties and structure of the obtained copolymers. We also reveal the possibility of controlled creation of cross-linked metal composites with predicted structure and a complex of properties.

Properties of Nickel Powder Alloys Hardened with Titanium Carbide

Abstract: We determine the melting point, hardness, and porosity of nickel powder alloys obtained by the method of hot pressing. A titanium content of 30–60 vol.% guarantees the wear resistance of alloys under the conditions of fretting corrosion. The heat resistance of these alloys was determined at a temperature of 1100°C and their wear resistance was found at temperatures of 20, 850, 950, and 1050°C. It is shown that, as the porosity increases, the heat resistance of the alloys decreases, and the characteristics of mean linear wear increase with temperature. We managed to obtain an alloy of the optimal composition with a melting point higher than 1300°C, which can be used in the aircraft industry.

Hydrogen Release on the Anode in the Course of Plasma Electrolytic Oxidation of Aluminum

Abstract: The process of preferential hydrogen release on the anode in the course plasma electrolytic oxidation is a result of the thermochemical reaction between aluminum dispersed in spark discharges and water vapor. It is shown that the products of interaction are aluminum hydroxides or oxides. In this case, the degree of oxidation and the maximum efficiency of the plasma electrolytic oxidation are attained in the case of inhibition of the reaction of hydration of the metal and the presence of sufficient amounts of oxygen in the reaction zone. It is discovered that the compounds present in the electrolyte capable of adsorption on aluminum and the cathodic current component suppress the reaction of aluminum hydration and promote the formation of oxides.

Adsorption Properties of Bentonite with In Situ Immobilized Polyaniline Towards Anionic Forms of Cr(VI), Mo(VI), W(VI), V(V)

Abstract: A new composite material bentonite-PANI was synthesized by in situ immobilization of polyaniline (PANI) on the surface of natural mineral bentonite. It was established as a result of the modification of bentonite a surface area and an interlayer distance of mineral decrease and particles of bentonite transformed of irregular shape with different porosity on irregularly shaped particles of smaller size. It has been found that the total Cr(VI) ions extraction took place under the acid conditions (pH=1 – 2) and W(VI) ions have been well adsorbed in the pH range from 1 to 8 by the composite bentonite-PANI unlike the initial mineral. Whereas adsorption of oxo anions of V(V) and Mo(VI) made up some 50%. It is proved that the in situ immobilization of bentonite by polyaniline leads to increasing the value of adsorption capacity towards the investigated ions compared with the initial mineral. It was established that the adsorption properties of the synthesized composite with respect to the studied oxo ions were worse than the adsorption properties of composite vermiculite-PANI, similar to the composite Sokyryntsyy clinoptilolite-PANI and better than composites of polyaniline with Podilskyy saponite and Karelian shungite.DOI: http://dx.doi.org/10.5755/j01.ms.22.2.6976

Fractographic Signs of the Mechanisms of Transportation of Hydrogen in Structural Steels

Abstract: We reveal various microfractographic signs of crack propagation in steels under the influence of hydrogenating media. These signs are related to the transportation of hydrogen in the process zone at the crack tip according to the diffusion or dislocation mechanisms. The intergranular fracture under cyclic loading shows that the hydrogen diffusion along grain boundaries is predominant. The transgranular fracture is caused by the combined action of the dislocation mechanism responsible for the intense hydrogenation of the metal along slip bands and the diffusion mechanism promoting the redistribution of hydrogen along the interfaces inside the grains.

Effect of Elevated Temperatures on Properties of Blended Cements with Clinoptilolite

Abstract: We have investigated the effect of elevated temperature on properties of clinoptilolite blended cements. Clinoptilolite was used at 5 %, 10 %, 15 % and 20 % replacement by weight for Portland cement while sand and water quantities were kept constant in all mix designs. Dry weights, flexural strengths, and compressive strengths of specimens were determined as a function of time. The same properties were again evaluated after specimens, having reached the age of 90 days, were exposed to 300 °C, 400 °C and 500 °C temperatures for 3 h. Initial setting times for all cements prepared were ≥ 60 minutes, the limiting time according to TS EN 197-1. The mortars with 5 % or 10 % cliniptilolite substitution have compressive strength exceeding 42.5 MPa after being subjected to 400 °C and 500 °C. DOI: http://dx.doi.org/10.5755/j01.ms.22.4.13354

New Metal-Hydride Electrode Materials Based On R 1–x Mg x Ni 3–4 Alloys for Chemical Current Sources

Abstract: We present a brief survey of works on the structure and hydrogen-sorption properties of some R–Mg–Ni alloys. It is shown that R–Mg–Ni alloys can be regarded as promising electrode materials for Ni/MH rechargeable batteries. Main attention is focused on the analysis of the properties of R1–x Mg x Ni3–4 alloys. The relationship between the composition of these alloys, character of isotherms, and electrochemical characteristics is discussed.

Cathodic Cage Plasma Nitriding of Ti6Al4V Alloy

Abstract: Glow discharge nitriding is being used increasingly more often for modifying the properties of titanium and its alloys with the aim to increase their frictional wear resistance, fatigue strength, and, in the case of medical applications, to eliminate the metallosis effect. Unlike PVD methods, ion nitriding ensures the formation of diffusive layers with very good adhesion to the substrate, but which still have some disadvanteges such as the “edge effect” or “hollow cathode effect” which hinders treatment of complex workpieces. The paper compares nitrided layers produced on Ti6Al4V alloy using two different types of nitriding processes. The first process is conventional dc plasma nitriding (DCPN) where the samples were placed at the cathode potential, while the second one is a new method of cathodic cage plasma nitriding (CCPN) process, where the substrate is insulated from the cathode and anode. The experiments have shown that the treatment conducted in a cathodic cage can be alternative for conventional ion nitriding, especially when used for small parts with complicated shapes used in the space or medical industry. DOI: http://dx.doi.org/10.5755/j01.ms.22.1.7343

Contact of Elastic Bodies in the Presence of Gas and Incompressible Liquid in Periodic Interface Gaps

Abstract: We study the contact of two elastic semiinfinite bodies in the presence of an incompressible liquid (that does not wet the surfaces of the bodies) and a gas in the interface gaps caused by a periodic array of grooves on the surface of one of the bodies. The drop of pressure in the liquid and in the gas is described by the Laplace equation. The problem is reduced to a singular integral equation with Hilbert kernel. This equation is then transformed into a singular integral equation with Cauchy kernel for the height of interface gaps. A system of transcendental equations for the lengths of the gaps and the regions filled with liquid is obtained from the condition of boundedness of the solution at the ends of the interval of integration and the condition of conservation of the amount of liquid. This system is solved numerically. We also analyze the dependences of the lengths and shapes of the gaps and the contact compliances of the bodies on the applied load, volume, and surface tension of the liquid.

The Aluminum Based Composite Produced by Self Propagating High Temperature Synthesis

Abstract: Self-propagating high-temperature synthesis method can be used for producing aluminum and boron carbide based composites. The experimental composites were fabricated using cobalt and carbon as catalysts. The microstructure of the material was studied using Scanning Electron Microscopy and the mechanical properties were determined using micro-hardness testing. Al/B4C based composites with improved properties were obtained and the role of Co/C catalysts was studied.

Influence of Hydrogen on the Residual Service Life of a Gas Pipeline in the Maneuvering Mode of Operation

Abstract: We propose a computational model aimed at finding the service life of a gas pipeline containing a surface corrosion crack under the action of long-term pressure discontinuous as a function of time (maneuvering mode of operation) and in the presence of hydrogenation of its wall. The model is based on the energy approach developed earlier by the authors and the proposed mechanism of intensification of corrosion processes by diffusively mobile hydrogen. The influence of hydrogenation on the residual service life of the gas pipeline in the maneuvering mode of operation is quantitatively estimated.

Influence of Environment on Ageing Behaviour of the Polyurethane Film

Abstract: In this work, UV-Vis spectra, FT-IR spectra, colour difference, yellowness index，and SEM micrographs were used to study the accelerated ageing behaviour of polyurethane films that exposed to UV radiation, O3 atmosphere, and UV/O3 integrated environment. During 200 hours of exposure in three different environment, the UV absorbance, the colour difference, the yellowness, and the absorption of –NH/–OH and –C=O bands in FT-IR spectra of the films increase gradually with increasing exposure time, respectively, and the films exposed to the three environments have different colour difference, yellowness index, UV-Vis spectra, and FT-IR spectra. The films are vulnerable to degradation and yellowing in the following environment order: O3 < UV < UV/O3. After exposure to UV radiation or O3 atmosphere, some degradation products and blisters are formed on the film surface. After exposure to UV/O3 integrated environment, there are strip blisters and micro-cracks on the film surface, and exists an obvious synergism between UV radiation and O3 atmosphere in accelerating the ageing of the polyurethane films.DOI: http://dx.doi.org/10.5755/j01.ms.22.2.12935

Microstructure and Abrasive-Wear Resistance of the Vibration-Deposited Metal of Core Wires of the Basic Fe–Cr–B System

Abstract: We investigate the microstructures of fused layers obtained by the welding from a core wire made of Kh10R4G2S steel. The presence of Fe2B and (FeCr)B inclusions distributed against the background of the matrix (solid solution of FeCr) in the microstructure of fused layers is confirmed by the phase and spectral analyses. If no vibration is used in the process of welding, then the sizes of borides vary from 10 to 150 μm2 (in the central part of the rollers) and from 50 to 300 μm2 (in the zone of overlapping of the deposited layers). The maximum effect of grinding of the (FeCr)B and Fe2B phases (up to 2–5 μm2 at the centers of the rollers and in the zone of their overlapping) was obtained by applying horizontal vibrations with an amplitude of ~ 300 μm in the course of welding. As a result, the microhardness of the fused layers increases and their abrasive wear resistance is also improved. The weight losses observed in the tests with fixed and nonfixed abrasives become 2–2.5 times lower.

Strength Development and Physical Properties of Cement Paste with Incorporated Ceramic Powder

Abstract: A possible usage of fine waste ceramic powder coming from precise brick cutting in production of blended cement is analyzed in the paper. For the studied ceramic powder, chemical and mineralogical composition is measured by X-Ray Fluorescence and X-Ray Diffraction. The particle size distribution of ceramic powder is accessed on laser diffraction principle. The ceramic powder is used in cement based pastes composition in cement mass replacements of 8, 16, 24, 32, and 40%. For the tested pastes, monitoring of strength development is done using measurement of time dependent mechanical parameters. Bulk density, matrix density, and total open porosity are measured for 28 days cured samples. In order to obtain information on the rate of hydration process, the formation of pastes’ solid structure is monitored using measurement of pore size distribution at chosen times of hydration. Application of waste ceramics is found to give the most promising mechanical properties of the cement-based paste for 8 and 16% cement replacement levels what makes good prerequisites for future research that will be focused on design and development of new types of cement-based composites with incorporated ceramic waste powder. However, also other tested mixtures provide acceptable results. This knowledge can be used for instance in the production of lower strength composites.

Micromechanical and Electrophysical Properties of Al 2 O 3 Nanostructured Dielectric Coatings on Plane Heating Elements

Abstract: By using the ion-plasma discharge system, an Al2O3 dielectric layer with nanoscale structure is formed on a plane heating element made of AMg2 aluminum-magnesium alloy. The sprayed Al2O3 layer consists of two sublayers with a total thickness of 13–15 μm and grain sizes of 4–306 nm. The surface roughness is equal to 50–60 nm. For the adhesion coefficient HSC ~ 1, the Meyer microhardness of the Al2O3 layer is equal to 0.788 and the Young modulus is equal to 75.433 GPa.

Lightweight Concrete with an Agricultural Waste – Buckwheat Husk

Abstract: This paper presents a parametric experimental study which investigates the potential use of buckwheat husk wastes (as an aggregate in concrete) and opoka combination for producing a lightweight composite. The study was carried out to investigate the influence of the buckwheat husk extract on the setting and hardening of pastes in which cement was partially replaced by 0, 33, or 50 % of natural pozzolana. The kinetics of hydration up to 48 h was studied using isothermal conduction calorimetry. Some of the physical and mechanical properties of buckwheat husk concrete with various levels of cement replacement of opoka without and with sand (part of buckwheat husk was replaced in the same volume of sand) were investigated. Experimental data on the compressive strength of concrete utilizing buckwheat husk with and without sand and cement at varying proportions are presented. The results suggest that buckwheat husk may be used as an aggregate, particularly in lightweight concrete, panel and blocks for walls at a relatively cheaper price.

Modeling of the Ordered Surface Topography of Statically Deformed Aluminum Alloy

Abstract: We propose an approach to modeling the ordered surface topography of D16chT aluminum alloy after static deformation. This approach enables us to establish statistic estimates of the parameters of formed surface irregularities with regard for the stochastic and cyclic nature of their self-organization.

Formation of the Structure of Cr 3 C 2 –MNMts 60-20-20 Cermets

Abstract: We study the structure of cermets based on Cr3C2 with binders of manganese German silver. These cermets are obtained by the impregnation of preliminarily pressed and sintered Cr3C2 frames with MNMts 60-20-20 German silver at 1150°C in argon. The prepared materials have a three-phase structure including of a solid solution based on copper, Cr3C2 , and (Cr, Mn)7C3 precipitating in the form of dispersed inclusions in the binder and on the boundaries of carbide grains.

High Temperature Sliding Wear of NiAl-based Coatings Reinforced by Borides

Abstract: The development of composite materials (CM) in the systems “metal-refractory compound” is one of the up-to-date trends in design of novel materials aimed at operating under the conditions of significant loads at high temperature. To design such material, NiAl, which is widely used for deposition of protective coatings on parts of gas-turbine engines, was selected for a matrix. To strengthen a NiAl under the conditions of intense wear and a broad temperature range (up to 1000 °C), it is reasonable to add refractory inclusions. Introduction of refractory borides into matrix leads to a marked increase in metal wear resistance. In order to research the behavior of the designed composites at high temperatures and to study the influence of oxides on the friction processes, the authors carried out high temperature oxidation of CM of the above systems at 1000 °С for 90 min. It was determined that all of the composites were oxidized selectively and that the thickness of oxide layers formed on the boride inclusions is 3 – 7 times that on the oxides formed on the NiAl matrix. The mechanism of wear of gas-thermal coatings of the NiAl – МеB2 systems was studied for conditions of high temperature tribotests using the «pin-on-disc» technique. The obtained results indicate that introduction of TiB2, CrB2 and ZrB2 leads to their more intense oxidation during high temperature tribotests as compared to the matrix. The oxides formed on refractory borides act as solid lubricants, which promote a decrease in wear of the contact friction pairs. For more detailed investigation of the effect of tribo-oxidation products on the friction processes, tribotests were conducted for prior oxidized (at 900 °С) coatings NiAl – 15 wt.% CrB2 (TiB2, ZrB2).DOI: http://dx.doi.org/10.5755/j01.ms.22.1.8093

Structure and Properties of Semifinished Sheet Products Made of an Intermetallic Refractory Alloy Based on Ti 2 AlNb

Abstract: We study the influence of two-stage thermal treatment on the formation of the phase composition, structure, and mechanical properties of semifinished sheet products made of VTI-4 refractory alloy based on the Ti2AlNb intermetallic compound. It is shown that, changing the temperature of heating in the first stage of treatment and the temperature of subsequent aging, it is possible to affect the strength and plasticity characteristics of the material in broad ranges. It is demonstrated that, in order to obtain a structure guaranteeing a relative elongation of 8–12%, the temperature of the first stage of treatment must remain in the (β + α2 + O) three-phase region and the procedure of cooling down to room temperature or to the temperature of the second stage of treatment (800–850°C) should be realized together with the furnace. To get high levels of short- and long-term strength at 650°C with preservation of moderate values of plasticity (3–5%), it is necessary to perform cooling after isothermal treatment in the three-phase region in air. The subsequent procedure of aging should be carried out within the temperature range 800–850°C for 7 h.