Ductile-to-brittle transition temperature as a measure of the crack resistance of steels

Conclusion In 1971 there was developed in collaboration with G. S. Pisarenko a model [19] of fracture of materials representing this process as a successive series of acts of origin of a microcrack at the tip of the main crack and their subsequent merging. In [20] the proposal was made for determination of the ductile-to-brittle transition temperature as the temperature corresponding to the appearance at the crack tip at the moment of fracture of a plastic zone of maximum size in which plane strain conditions are still satisfied. In it on the basis of the earlier proposed model there was obtained a determining relationship relating the transition temperature to the basic parameters influencing it, specimen dimensions, loading rate, and structure of the material. As the result of fruitful collaboration with Professor D. Francois and the presentation by him of broad experimental data on the scale effect in the ductile brittle transition in various steels it was possible to experimentally base the relationships obtained and to propose certain relationships useful for practical purposes [7]. Since [7] is not yet known to Soviet readers, it was appropriate to first give it a brief presentation and then to develop some of its proposals to other cases not touched upon in this work.Institute of Strength Problems, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Problemy Prochnosti, No. 10, pp. 89–95, October, 1985.     

A Device for Measurements of Dielectric Characteristics of Liquid Crystalline Materials, Solid Substances, and Their Melts

The device developed allows one to measure the dielectric characteristics of solid substances and their melts at frequencies of 20–20000 Hz and in a wide temperature range of 20–250°C. The measured temperature dependencies of the dielectric permittivities of several molecular and liquid crystals (stilbene, diphenyl, naphthalene, cholesterylpelargonate, and 8OCB) are presented.     

Analysis of self-similar laminar flows in slot channels with one permeable wall

An analysis is made of the fluid flows in a plane slot permeable channel. It is shown that for large numbers R (suction) self-similar solutions exist.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 49, No. 3, pp. 432–436, September, 1985.     

Solution of the Inverse Problems of Scattering of Electromagnetic Fields by Elongated Defects

We formulate the inverse problem of scattering of electromagnetic fields by thin defects and analyze numerical algorithms used for its solution. It is shown that, in the two-dimensional case, the shape of a thin defect is completely determined by the scattered field given on a certain curve for a fixed value of the wave number. For the solution of the inverse scattering problem, we propose to use the procedure of iterative regularization based on the gradient methods. We deduce expressions for the Fréchet derivative of the operator of direct scattering problem with Dirichlet conditions imposed on the surface of a scatterer.     

Production of high-strength tubes made of steels of type 15GFB

A unit for making L-class high-strength pump-compressor tubing composed of low-carbon, low-alloy steels of type 15GFB is now being used on the 140 mill in the tube-rolling shop at the Rustavi Metallurgical Plant. The steel 15GFB pump-compressor tubing made by the technology that was developed has the following service properties: σ_y = 630–670 N/mm², σ_u = 730–780 N/mm², δ = 18–22%, ψ = 55–60%, KCU = 1.6–2.2 MJ/m². The percentage of ductile fracture at room temperature is 85–95%. __________ Translated from Metallurg, No. 1, pp. 79–80, January, 2006.     

Physical nature of empirical time dependencies of the strength and failure characteristics of materials

Correlations between each of two parameters of empirical relationships describing arrays of experimental data on the long-term strength, creep, multi- and low-cycle fatigue, and the growth of fatigue cracks are established. Well-defined relationships between parameters within each array make it possible to reduce significantly the required volume of material tests. The physical essence of the observed correlations is associated with the thermally active nature of damage processes, which accompany each form of material tests. It is demonstrated that the pattern of the dependence of correlating empirical parameters on fundamental characteristics of thermally activated damage processes can be established for all types of tests under consideration: the height of the potential barrier, the frequency factor, etc. For all types of tests, analytical predictions are in good qualitative agreement with correlations observed in experiment.Translated from Problemy Prochnosti, No. 6, pp. 3–9, June, 1994.     

Apparatus for the automatic measurement of low-frequency acoustical parameters of anisotropic liquids

A measurement and computing system designed for acoustical investigations of liquid crystals, magnetic fluids, etc., in the frequency range 0.15–1.2 MHz is described.Translated from Izmeritel'naya Tekhnika, No. 2, pp. 51–53, February, 1994.