Peculiarities of metal behaviour under high-temperature creep-fatigue fracture are analyzed. The main approaches to prediction of the metallic constructions lifetime are considered. The results of numerous investigations of high-temperature creep-fatigue behaviour of various alloys, which are used for producing turbine elements, components of the power generating station, pipelines etc. are shown. Some common features have been described, for example, longer holding times and lower cycling frequencies often lead to the higher growth rate of the crack and its greater intergranular propagation. These effects are usually greater at higher temperatures and are more pronounced when specimens are tested in oxidizing environments rather than in the inert environments. The value of these effects, particularly in oxidizing environments, depends strongly on microstructural parameters such as grain size and shape, and also grain boundary chemical properties. Some of these factors were considered in more details.

The interface crack problem in a composite layer under antiplane state of strain is investigated. The body is a four-component elastic composite composed of periodically repeated elements with rectangular cross-sections. Each cell is constructed with four rectangular bars with rectangular cross-sections. The finite interface crack, free of loading, is located on the middle plane of the layer. The displacement distributions on the boundaries of the layer are given. The stress intensity factors at the crack tips are determined for arbitrary mechanical properties and dimensions of the cells.

Modification of the boundary integral equations method is proposedВ. It allows us to solve effectively problems about interaction of a large number of arbitrarily oriented plane cracks on an engineering level. The method is based on the evaluation of the effective stress field which is generated in the vicinity of the fixed crack by the neighboring cracks inter-acting with it. Reliability of the results, obtained by the method of effective stress field is proved by comparing them with exact solutions of the problem of interaction of two plane circular cracks of different location. EffiВciency of the method is illustrated by the example of interaction of nonperiodic system of six cracks located in different planes.

Proceeding from laws of conservation of an energy and an electromagnetic field momentum with use of the statistical approach and an introduction of equivalent tensions formalism, the expressions for densities of electromagnetic energy reserved in a polarizing and (or) magnetizing body (reversible part) and absorbed in it (irreversible part), as well as for densities of ponderomotive (volumetric) and surface forces as well as the moments of forces have been obtained. These expressions for various materials and types of electromagnetic fields are compared with known in the literature. The proposed factors are starting points for definition (on the basis of the asymmetric theory of thermomechanics) of the temperature fields and mechaВnical stresses caused by the observed types of electromagnetic effect.

The dynamic problem about an elastic hollow two-layered cylinder with surfaces loaded arbitrarily by forces depending on time is solved by a method, based on using finite difference with respect to time. Numerical calculations of the stress concentration on inner and outer surfaces and between layers, depending on time for cylinders of different width under impact loading have been done. The spatial dependences of stresses on radial variable r and time parameter t for a two-layered cylinder in case of impact on its inner and outer surfaces are illustrated.

The contact of elastic half-spaces when there is a compressing liquid inside an elliptic intercontact gap is considered. The formulated problem is reduced to an analytically solved integro-differential equation with respect to the gap height. The dependence of geometrical characteristics of the gap on external loading is analyzed.

The kinetics of diffusive saturation of О±-titanium by nitrogen in rarefied atmosphere (1 Pa) in the temperature interval 750¦850п‚°C is experimentally and analytically investigated.. The estimation of the influence of temperature and time parameters on the depth of the nitrided layer and a change of its microhardness is given.

The non-typical example of stress corrosion cracking of the low-strength high-plasticity steel 20 from the internal chock surface after 35 year exploitation in the oil-hydraulic pump has been presented. The conclusion has been drawn that the working oil by its influence on mechanical behaviour of long-term exploited metal should be considered as an aggressive environment. The effect of environment is intensified by the preliminary plastic deformation near the hole surface layers because of drilling the hole in the choke. Subcritical crack growth from the internal surface of the chock with a great number of secondary cracks has been found fractographically. It is the result of the hydrogen-induced embrittlement of the metal degraded during long-term exploitation.

Results of the fatigue tests of steel specimens with different carbon content have been presented. The dislocation model of the strengthening of a two-phase plastic deformed solid has been proposed. According to this model the formula for estimating the efficiency of hard facing as well as the increase of the fatigue resistance of the structural steels has been improved.

The service characteristics of the welded joints of austenitic high-nitrogen steels are analyzed. The influence of chloride and hydrogen-containing environments on structural properties of heterogeneous welded joints has been investigated. It is established that the most sensitive area to the influence of hydrogen embrittlement is the heat-affected zone, where except for residual stresses the stresses of external environment and defects are imposed.

The modulus of elasticity, microhardness, crack growth resistance and specific resistance of single-crystals of hexaboride lanthanum with a perfect structure, which can serve as tabular information, were determined. Energy of covalently binding between the atoms of B–B and also total energy of binding of LaB6 and diboride of transition metals was calculated, that allowed to explain high mechanical characteristics of hexaboride lanthanum.

We propose a new method by fractal analysis on atomic force microscopy (AFM) phase images to characterize molecular adsorption film of corrosion inhibitor on polycrystalline coarse surface, which can hardly be distinguished by AFM height images owing to the surfaces roughness. The system of polycrystalline aluminum and inhibitor SDS (Sodium Dodecyl Sulfate) is chosen as the research object. Electrochemical measurements of aluminum electrodes pre-filmed with SDS are carried out in HC1 solution, and the result shows that the inhibition efficiency increases with the increasing of SDS concentration in the prefilming solution, and then keeps nearly constant while the CMC (critical micelle concentration) of SDS is exceeded. Fractal analysis for AFM images of pre-filmed aluminum surfaces obtained in SDS solution is performed and demonstrates that, with SDS concentration increasing, no obvious change happens to fractal dimensions of height images, whereas phase images present regular changed fractal dimension values, displaying the consistent alteration rule as revealed by electrochemical tests. The results prove the feasibility for fractal analysis of AFM phase images to characterize adsorption behavior of corrosion inhibitor on polycrystalline coarse surfaces.

Diffusion brazing of TiCAl2O3 ceramic composite with W18Cr4V tool steel was conducted using Ti and Cu filler metals at 1500 K for 1 h with a pressure of 15 MPa in a vacuum of 105 Pa. Thus a brazed TiCAl2O3/W18Cr4V joint was achieved with the interfacial shear strength is up to 105 MPa. The microstructural characteristics in the TiCAl2O3 /W18Cr4V joint were studied by scanning electron microscope (SEM) with energy dispersion spectroscopy (EDS) and X-ray diffractometer (XRD). The results indicated that an interfacial layer with a thickness of 90 Ојm was formed between TiCAl2O3 and W18Cr4V steel. Ti and Cu filler metals fully fused and diffused to react with Al and C from substrates and Ti3Al, Ti3AlC2, TiC and CuTi2 were produced in the TiCAl2O3 /W18Cr4V joint.

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