SUMMARY. Basing on the known с-model [1] and using the revised peculiarities of distribution of the interaction stresses between the model cut edges in the material process zone, the formulas for calculation of crack tip opening displacement have been established. These formulas were used for calculation of the critical stresses.

SUMMARY. The test method of dynamic stress state of a three-dimensional isotropic body with a rough inclusion for external dynamic effects is proposed. The problem is reduced to the known problem of solutions mating of the Lame wave equation in areas with the rough boundaries, which with the help of the known elastic delayed potentials of the simple and double layer as well as of the volume is reduced to the system of the functional equations solved by the method of successive approximations. The method is illustrated on the example of a skew stress field with a circular conic inclusion in the case of the sudden application of the load.

SUMMARY. The dynamic problem about on the anti-plane deformation of the solid with the thin rigid strip inclusion is solved. The solution is based on the application of the modified method of finite differences by time and the use of the discontinuous Helmholts equation in each time-node. The results of the numerical analysis of the change of the stress intensity factor (SIF) for the inclusion depending on time for different loading modes are shown.

SUMMARY. The procedure for the determination of the cyclically loaded notched specimens endurance is proposed. It is based on the model of fatigue fracture that considers the process of the macrocrack initiation and propagation from a unified approach. For two types of specimens with the structural stress concentrator the number of loading cycles to their failure was estimated based on fatigue macrocrack growth rates only. The calculational results and the experimental data agree with a deviation of no more than 38%, depending on the calculation method and durability.

SUMMARY. The problem on the bending-tension of a shallow shell with a crack in two-dimensional statement has been considered. The crack closure under bending is described within the framework of the classical shell theory using the model of the crack edges contact along a line in the face surface. The influence of the crack edges contact interaction and surface curvature on the stressed state and limit equilibrium of cylindrical and spherical shells has been investigated.

SUMMARY. A new epoxy composition for antistatic coatings on metallic surfaces, filled with the mixture of technical carbon and talc powder, surface modified by paranitroaniline and phosphoric acid was studied. It was revealed, that introduction of modified filler mixture increases gel-fraction content in epoxy coating by 5...6%, adhesion in 2,5–2,7 times and decreases the organic solvents content. It was established by impedance measurements, that electrical resistance of the new coating is more stable in time than that of the commercial antistatic primer-paint and its frequency dependence is strongly pronounced after exposure to corrosion solution, testifying the higher protective properties of the coating with modified conductive fillers.

SUMMARY. The peculiarities of phase forming and gas saturation in carbon-nitrogen containing media at 1100C and 5 h exsposure time of c.p. titanium and BT14, OT4, BT20 titanium alloys have been investigated. It has been shown that carbonitrides TiCxNy of different composition are formed depending on alloy composition. Investigation of corrosion and electrochemical behaviour revealed that carbonitride formed on BT20 with the composition similar to the equiatom one, has the best protective properties and the lowest roughness.

SUMMARY. The effect of the electrolytic hydrogenation conditions of steels and corrosion properties in hydrogen galvanic couple (HGC) “hydrogenated metal-unhydrogenated metal” in dependence on their structure and рН of environment is investigated. Correlation between the parallel reactions of hydrogen and iron oxidation in HGC is evaluated on the basis of polarisation parameters and mass corrosion losses of the hydrogenated 45 steel. Just after hydrogenation the HGC current is limited by the diffusion hydrogen flow desorbed from steel and a fraction of the iron oxidation reaction is about 20% of a total current. The corrosion rate under such conditions is by 20–30 times higher than that for the unhydrogenated metal. With time a total current and intensification of iron decrease but the role of the last one increases. HGC of 45 martensitic steel absorbs less hydrogen than the pearlitic one and, correspondingly, is characterised by lower current but longer period of functioning. The decrease of рН reduces HGC parameters (electric driving force and initial current) for 45 steel and as a result the protective properties of the surfaces oxide films deteriorate. Hydrogen absorbed by stainless steel intensifies its general corrosion in HGC and causes a tendency of steel to pitting corrosion.

SUMMARY. The effect of the electrolytic hydrogenation conditions of steels and corrosion properties in hydrogen galvanic couple (HGC) “hydrogenated metal-unhydrogenated metal” in dependence on their structure and рН of environment is investigated. Correlation between the parallel reactions of hydrogen and iron oxidation in HGC is evaluated on the basis of polarisation parameters and mass corrosion losses of the hydrogenated 45 steel. Just after hydrogenation the HGC current is limited by the diffusion hydrogen flow desorbed from steel and a fraction of the iron oxidation reaction is about 20% of a total current. The corrosion rate under such conditions is by 20–30 times higher than that for the unhydrogenated metal. With time a total current and intensification of iron decrease but the role of the last one increases. HGC of 45 martensitic steel absorbs less hydrogen than the pearlitic one and, correspondingly, is characterised by lower current but longer period of functioning. The decrease of рН reduces HGC parameters (electric driving force and initial current) for 45 steel and as a result the protective properties of the surfaces oxide films deteriorate. Hydrogen absorbed by stainless steel intensifies its general corrosion in HGC and causes a tendency of steel to pitting corrosion.

SUMMARY. The temperature dependence of thermal expansion factor (TEF) of the monocrystalline silicon was investigated at normal (atmospheric) pressure. The change of the value and the sign of TEF of the specimens (to 400 %) of monocrystalline silicon with exact crystallographic orientation and insignificant (15) disorientation in the temperature variation range from 323 to 1473 K at normal pressure has been studied. The crystallographic direction of the specimens was <111>, <110>, <112>. The TEF of specimens with a crystallography direction <110> are much less dependent on temperature variation to compare with others.

SUMMARY. The development and consequences of introduced by H. Karpenko investigations in the field of structural control of the mechanical and corrosive-mechanical properties of structural steels are outlined. The work is based on the various kinds of thermal and thermomechanical treatment of the alloys and also use of the strengthening coatings on structural materials. The mentioned investigations were further developed in the field of structural fracture mechanics of metals and alloys. Some results are outlined and contraversive problems connected with proper evaluation of the structural strength are indicated. They concern the uneffectiveness of approaches based on the behaviour of macrocracks and necessity to take into account the structural and electrochemical phenomena of crack initiation in metals and alloys.

SUMMARY. Basic achievements of Physicomechanical Іnstitute of the National Academy of Sciences of Ukraine are listed in the field of hydrogen induced degradation of metals. The localization of hydrogen in a crystal lattice and in the defects of metals as the main reason for changes of properties by decohesion mechanism is considered.

SUMMARY. The prospects of utilisation of electrode TiN–Cr-based materials for formation of wear-resistant spark coatings by the influence of concentrated solar energy have been shown. Treatment by concentrated solar energy of spark TiN–Cr coatings increases the wear-resistance of the coatings by 2–3 times. It is established that spark 40%TiN + 60%Cr coating possesses the optimum thribotehnical and physicomeсhanical properties.

SUMMARY. The abrasive and cavitation wear resistance of the specimens from tungsten and В3К alloy in comparison to ВР-27ВП alloy has been determined.