The necessity to enhance the operating characteristics of boiler steels is related to a continuous increase in corrosion damages of pipes of heating surfaces. Therefore, the actual task remains the development of ways to enhance the corrosion resistance of pipes made of grade 20, which are used as heat-absorbing elements in heat power engineering. The effect of cyclic modes of normalization (repeated structural recrystallization) on microstructural characteristics and the mechanical and corrosion properties of grade 20 steel in accordance with the regulatory requirements for products of this kind is studied. It is established that twofold normalization for grade 20 carbon steel is the optimum heat treatment mode for equalizing the ferrite grain sizes and decreasing the corrosion rate. It is revealed that this heat treatment mode increases the inequigranularity factor by three times in comparison with the original magnitude. Subsequent normalization cycles result in the formation of rejected microstructures and a decrease in mechanical properties of metal. The increased homogeneity of the microstructure at the double normalization decreases the corrosion rate by 38–51% of the original magnitude. The obtained results can be used for prolongation of the operation life by a decrease in the corrosion rate in pipes normalized twice as well as for the calculation of the remaining life of heating surfaces of boilers of heat power plants.

The nonisothermal mass transfer in metal materials under irradiation with concentrated energy fluxes is studied in the one-dimensional approximation. Local nonequilibrium equations of extended irreversible thermodynamics are used to describe the transfer phenomena. It is established that, for short times (on the order of the time required for relaxation of the diffusion flow to its local-equilibrium value), the wave mechanism for mass transfer is dominant over the diffusion one, ensuring that the impurity-concentration profiles have a nonmonotonous form. The degree of influence of the space-time nonlocality of the transfer processes on the formation of concentration profiles is estimated, and the model results are compared with the experimental data.

The article considers the effect of the inequigranular structure of carbon steel 20 (0.2 wt. %C) on the electrochemical corrosion rate observed on the pipe outer surface of the dismantled panel heating surface. The morphological analysis of structural components of steel 20 was performed using the “Resource C7” metallographic analyzer of microstructure fragments of solid bodies. It was shown that due to the development of electrochemical corrosion the value of the inequigranular factor will determine the thinning speed of wall thickness, depth and width of inter-crystalline corrosion cracks. The higher is the given parameter (as well as grain structure uniformity), the lower is the general corrosion rate and the less is the depth and the width of intercrystalline cracks developing from the pipe outer surface. The results obtained can be used to calculate the pipe residual life of heating surfaces.

The microstructure of heat-affected zones produced by high-power ion beams in Al, Cu, Ni, and AD1 and Monel alloys are investigated by optical and scanning electron microscopy and X-ray diffraction analysis. It is ascertained that the microstructure is divided into characteristic layers differing in terms of grain sizes and phase components. It is shown that the formation of the structural-phase states of each layer occurs in both solid and liquid phases under pulsed ion-beam treatment and depends on the irradiation parameters and the thermophysical characteristics of a target.

The concentration profiles of aluminum ions in polycrystalline titanium implanted by the polychromatic beam from a vacuum arc source via a gas-and-metal film deposited on a target surface are analyzed.

Rapid crystallization in binary systems under the effect of high-energy beams of charged particles was described using a model of mass transfer taking into account both the space and time nonlocality. The role of physical constants and parameters of crystallization in the formation of the material microstructure during rapid solidification of binary alloys is evaluated.

The formation of preferred orientations in metal targets under exposure to intense ion beams was studied using x-ray diffraction. The formation of axial textures with [111] and [100] axes, observed in aluminum, copper, and nickel samples, depends on both the ion current density and thermal characteristics of the target material. In the case of rapid propagation of the thermal front to the material depth, the texture is apparently formed by the dislocation mechanism, which occurs in copper samples having the highest thermal conductivity. For aluminum and nickel, the most probable are recrystallization and regrowth mechanisms, respectively. An analysis of inverse pole figures showed that the main direction of heat sink in textured samples corresponds to the normal to the (111) atomic plane.

The qualitative phase analysis and measurement of lattice parameters, lattice distortions of the second kind, and coherent domains of tungsten-carbide mosaic subblocks are discussed. It has been found that the implanted metals form oxides in the near-surface layer, thus enhancing the wear resistance of the material in tribomechanical contact. Kinetic relations have been developed for the wear of the irradiated surfaces of the hard alloy.

It is reported that two types of damage structure occur in ionic crystals. They are brittle disk-shaped cracks and clusters of spherical micropores with a diameter of the order of 10 μm. It is shown that such damage structures begin to form when the stress exceeds a critical value. Thresholds of formation of such structures are determined

A study was made of the influence of elastic stress pulses on the dynamics of fracture of ionic crystals by high-density electron beams. Confined acoustic fluxes generated in solids by electron irradiation interacted effectively with various microcracks, causing them to grow and split the affected crystals.

Results are reported on the damage of ionic whisker crystals having a high mechanical strength. The radiation source is an electron accelerator with the following parameters: maximum particle energy 0.3 MeV, pulse length adjustable in the interval (2-30) . 10/sup -9/ sec, and beam current adjustable in the interval (0.005-1.5) . 10/sup 3/ A/cm/sup 2/. Samples of KCl and KBr whisker crystals of 25-30 ..mu.. diameter were bombarded by single pulse in vacuum. The damage criterion was the splintering of part of the sample.