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|Heorhii Volodymyrovych Karpenko. (To the 95th birthday)|
|Panasyuk V. V. and Pokhmurskyi V. I. Academician H. V. Karpenko and creation of a new scientific direction “Physicochemical mechanics of materials” |
SUMMARY. A key role of Academician Heorgii Volodymyrovych Karpenko in development of scientific direction “Physico-chemical Mechanics of Materials” and in formation of Physico-Mechanical Institute of the National Academy of Sciences of Ukraine, as a leading materials science centre, is considered.
|Romaniv O. M. and Nykyforchyn H. M. Adsorption effect in corrosion fracture mechanics |
SUMMARY. The review of the adsorptive decrease of crack growth resistance in metals and alloys as a component of the general Karpenko theory about a role of adsorption in physicochemical mechanics of materials is presented. The static and cyclic loading, fracture toughness and delayed fracture in liquid and gaseous environments are considered. Special attention was paid the methodical aspects of experimental investigations, to choosing the model adsorptive-surface active environments. The principal experiment that proved the adsorptive effect of the decrease of sustained static crack growth resistance in high-strength steel in high purified dimethylsulfoxide is analysed.
|Kocanda D., Kocanda S., Lunarska E., Mierzynski J. Possibility of hydrogen-assisted propagation of short fatigue cracks in WT3-1 titanium alloy|| |
|Andreikiv O. Ye. and Hembara O. V. Hydrogen-induced crack propagation in metals under long-term static loading |
SUMMARY. A calculation model of crack growth caused by hydrogen and long-term static loading is proposed. The model is based on the energetic criteria of materials fracture. As a result, the crack growth rate was obtained as a function of load, dimensions of the initial crack, physicochemical and strength characteristics of the material. Theoretical curve agree well with experimental data.
|Pokhmurska H. V., Student M. M., Chervinska N. R., Smetana Kh. R., Vank A., Hoenig T., and Podliesiak H. Structure and properties of aluminium alloys, laser modified with silicium carbide |
SUMMARY. The structure and properties of АА6082 and АА7075 aluminium alloys, modified with SiC by the laser. It is established, that wear resistance of such reinforced alloys is 30–75 times higher than that of the unmodified ones under friction with the rigidly fixed abrasive wheel. On the basis of electrochemical researches it is shown, that for АА7075 alloy the influence of structural heterogeneity on the change of corrosion potentials decreases with increase of aggressivity of the corrosion environment. Corrosion current values of the surface of АА6082 and АА7075 alloys in various corrosion solutions are established.
|Horopatskyi V. H. and Stashchuk M. H. The change of electrode potential along the interface of a deformed metal body and an electrolite |
SUMMARY. The effect of the load on the change of the electrode potential along the interfaces between the elastic non-ferromagnetic electric conductive bodies and corrosive liquid media is studies. The relations that allow to evaluate the effect of elastic deformations on the corrosionc damage of metals, and thus to calculate the corrosion resistance in order to predict the durability of metal products and structural elements in service conditions are given.
|Kardas G. The inhibition effect of 2-thiobarbituric acid on the corrosion performance of mild steel in HCl solution|
|Malyshev V. V. and Hab A. I. Electrochemical investigation of carbonization of molibdenum and tungsten in oxide melts |
SUMMARY. The phase overvoltage during initiation of molybdenum and tungsten carbides crystals in oxide tungstate-molybdate-carbonate melts is determined by the material of substrate and electrodeposition conditions (temperature of melt, current density, electrolysis duration). Temperature growth may complicate the crystallization processes by alloy forming processes. Structure conformity of deposits is determined by the nature and structure of the substrate.
|Buria O. I., Kozlov H. V., and Chyhvintseva O. P. Mechanism of energy dissipation during impact testing of carbon-filled plastics based on phenilon |
SUMMARY. The results of impact tests of carbon plastics based on phenilon are presented. It is shown that impact energy dissipators in carbon plastics based on phenilon are porously packed areas of volumetric polymer matrix and interface areas. Is is stated that impact energy dissipation is realized at the account of two mechanisms: molecular mobility typical for rubber resin, and shear mechanism typical for glass-like polymers.
|Skriabina N. E., Fruchar D., Spivak L. V., and Sheliakov A. V. The influence of hydrogen on crystallization of amorphous Ti50Ni25Cu25 titanium alloy |
SUMMARY. The previously unknown effects in physics of interaction of hydrogen with amorphous metal alloys are described: the increase of the crystallization temperature of hydrogen-containing Ti50Ni25Cu25 alloy and reduction of the reverse martensitic transformation В2 В2 after crystallization are described.
|Halaziuk V. A. and Sulym H. T. Stresses at a disk-like sharp slit with a tangential contact interaction between its faces |
SUMMARY. A new formulation of the problem on elastic equilibrium of a disc-like slit, whose surface is loaded by an arbitrary tending by a special law to zero on its front, normal loading is proposed. Using the Weber-Schaftheitlin discontinuous integrals method, it is proved that in the given loading case, a unique state of elastic equilibrium on its front exists. According to the concept of a boundary layer , the tangential stresses jump on the slit surfaces arising in this case due to continuity of the components of a local rigid rotation vector on its fronts, extends in its plane and provides the fulfillment of the equilibrium conditions under the equality to zero of normal stresses (the boundary layer effect). Numerical analysis shows that the jump of tangential stresses in the boundary layer outside a slit decreases rapidly when it is removed from the front in agreement with the principles of Saint-Venant. In the absence of the tangential stresses on the slip surface (it exists outside it), these surfaces on its front form a fracture surface, while a volume deformation on it has a logarithmic singularity. Such a situation can be considered as a limiting state at which plastic deformation or brittle fracture begins. If the tangential stresses jump in the slit plane is absent, there is no solution to this problem.
|Hachkevych O. R. and Ivas’ko R. O. Thermoelastic state of a ferritic layer in quasi-static electromagnetic field |
SUMMARY. The electromagnetic temperature and mechanical fields in the elastic ferritic material under the effect of electromagnetic field, produced by quasisteady current in the plane parallel to the layer base are determined and investigated. Regularities in distributions of electric and magnetic field strength, heat sources, ponderomotive forces, temperature and stresses in magnetic soft Ni–Zn ferrite layer dependent on its thickness and parameters of electromagnetic field are established. In particular, the stresses distributions in the vicinity of resonanse frequencies are investigated. The results can be used in development and improvement of service regimes for ferrite elements in electric and electronic devices.
|Stankevych V. Z. Stresses at a crack in a semi-space contacting with fluid under harmonic loading |
SUMMARY. The 3-D problem of bimaterial object “elastic half-space with cracks–liquid”, under time-harmonic loadings on the cracks faces, has been considered. The problem is reduced to solving the two-dimensional boundary integral equations of Helmholtz potential type system with the unknown jumps of displacements across the cracks opposite faces. As an example, the steady-state load on the penny-shaped crack faces is considered. The inertial effects in the neighbourhood of the crack contour are investigated.
|Bulyk I. I., Basaraba Yu. B., Trostianchyn A. M., and Davydov V. M. Disproportionation in hydrogen and recombination of Laves-type phases of zirconium with chromium |
SUMMARY. The conventional and solid HDDR (Hydrogenation, Disproportionation, Desorption, Recombination) for the ZrCr2 compound with a structure of C14 and C15 types under the initial hydrogen pressure 3 and 5 MPa and temperature range from the room temperature to 1243 K were investigated by means of differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscope (SEM). It was established that ZrCr2 compound with the C15 type Laves phase is decomposed into ZrHx and Cr at 1048 and 1093 K at = 5 and 3 МРа and is recombined in vacuum. The disproportionation temperature of the Laves phase with the structure of C15 is by 120 K lower than that of the C14 phase. With the hydrogen pressure increase, the disproportionation temperature decreases. Application of HDDR for reconstruction in ZrCr2 C14 and C15 Laves phase composition allows to decrease the temperature and treatment durability to compare with annealing in vacuum. HDDR forms the nanostructure in ZrCr2.
|INVESTIGATION AND TEST METHODS |
Aksionova S. I., Liubchenko A. P., Uchanin V. M., Melanchuk V. Yu., Tikhomirov B. V., and Yavorovych S. I. Detection of defects in refrigerator tubes in diesel locomotive engines by an eddy current method
SUMMARY. The dynamic eddy current device for thin-walled tubes testing with rotation of eddy current transducer around tubess is presented. The effectiveness of different methods of tube testing was analyzed. It was shown that the eddy current method allows detection of the largest number of defective tubes to compare with other test methods: the visual and hydraulic evaluation methods. Beside this the eddy current method productivity is 8–10 times higher than that of the others. The possibility of eddy current to estimate the defect depth and the level of defect danger by the eddy current device amplitude was shown. The possibility to set up the optimal reject criterion and corresponding level of eddy current device indication and to reject tubes with defects greater than the permissible ones was demonstated. So the number of false rejection was reduced. The eddy current dynamic device LEOTEST VD-5 was introduced in locomotive Diesel engine production technology.
|SCIENCE FOR PRODUCTION |
Timofeiev B. T. and Bazaras Zh. L. Low-cycle fatigue of NPP equipment made of 15Х2МФА steel
SUMMARY. Experimental results on low-cycle fatigue of 15Х2МФА steel and its welds, widely used for ВВЕР-440 reactors, have been summarized. This information has been received on a rather large number of base metal melts (21 heat treatments) and welded specimens (16 specimens). Experimental data have been compared with Reference curve for low-alloy heat resistant steels in Strength Calculation Norms ПНАЕ Г-7-002-86. It has been shown that the values of margin factors nσ =2 and nN = 10 in fatigue strength assessment of equipment from 15Х2МФА steel are provided for base metal and this is very important in connection with service life extension of ВВЕР-440 reactor equipment for 10–15 years.
|Pichuhin A. T., Fedirko V. M., Lukianenko O. H., and Onuferko V. S.
ВТ1-0 titanium alloy endurance after solid solution surface strengthening |
SUMMARY. The influence of solid solution strengthening (method of thermal diffusion saturation from a rarefied oxygen containing gaseous medium) of BT1-0 titanium alloy surface layers on its fatigue endurance is investigated in the specimens under rotating bending. It is shown that the dependence of fatigue limit on the surface strengthening factor has a maximum, the value of which depends on the depth of the strengthened zone. The 38% growth of the initial fatigue limit of BT1-0 alloy is reached when the surface strengthening factor, K, (relative increase of surface hardness) is 70% and the depth of the strengthened zone, l, is 30 μm.
|SHORT REPORTS |
Balytskyi O. I., Ripei I. V., and Protsakh Kh. A. Degradation of steam turbines cast elements of 20ХМФЛ steel in TPP after long-term operation
|Mudryi S. I., Korolyshyn A. V., Kotur B. Ya., Bednarska L. M., Hertsyk, and Kovbuz M. O. Assessment of a volumetric fraction of crystal phase in amorphous alloys|