Hereditary influence of the starting structure of powder particles on the mechanical properties of 30KhN3MF constructional steel

Conclusions An investigation into the structure and morphology of a 30KhN3MF steel powder produced by atomizing a jet of liquid metal with nitrogen has shown that the rapid cooling experienced by the particles of such a powder ensures a predominantly cellular character of solidification. In the particles of the 30KhN3MF steel powder intercellular microsegregation of alloying and impurity elements is observed. A P/M material produced by HIP is free from internal discontinuities, but individual granules surrounded by oxide films are clearly visible in its macro- and microstructures. The presence of these films, by disturbing the homogeneity of material, has an adverse effect on the mechanical properties of the steel after HIP. P/M 30KhN3MF steel fractures over the surfaces of its powder particles. Plastic working and subsequent heat treatment of 30KhN3MF steel sheets ensures that, at the same level of toughness and strength and ductility characteristics in static tensile testing, the work of crack propagation is greater compared with 30KhN3MF steel produced by the orthodox process. The rupture of 30KhN3MF steel sheet has a dual character, tough, fine-grained fracture predominating between the oxide film layers, along which regions of lamination and cleavage can be detected.A low-alloy 0.30% C-Cr-3% Ni-Mo-V grade-Translator.Translated from Poroshkovaya Metallurgiya, No. 9(213), pp. 77–82, September, 1980.     

Apochromatic correction of the rigid GRIN endoscope

A technique for apochromatic correction of rigid endoscope’s visual channel with an objective and a gradient-index relay is described. The technique consists in incorporating a corrector with a diffractive lens and one or two homogeneous refractive lenses. It is shown that the three-lens corrector can substantially reduce monochromatic aberrations of the system.     

Circular cylinder in a transonic flow at high Reynolds numbers: Thermal problem

The results of numerical simulation of transonic cross flow of a perfect gas around a circular cylinder at high Reynolds numbers are used to solve the thermal problem. The temperature distributions along the central line and the influence of Reynolds and Mach numbers on them are presented. The temperature fields and the transition of the near-wake solution to the far-wake solution are studied.     

Theoretical-experimental model for predicting crack growth rate in structural alloys under combined action of fatigue and creep

Holding periods of 300 and 3600 s in a trapezoidal load cycle are shown to increase the crack growth rate dozens of times for alloy éP962 and several-fold for alloy éP742 at a temperature of 973 K. It is demonstrated that in the presence of the first portion on the creep crack growth diagram, whereon the crack growth rate decreases, the crack growth kinetics for a trapezoidal load cycle can be predicted using the hypothesis of the linear summation of fatigue and creep crack growth rates provided that the peculiarities of the first portion of the creep crack growth diagram are taken into account. Empirical approaches are proposed for determining the mean crack velocity in the first portion of the creep crack growth diagram. __________ Translated from Problemy Prochnosti, No. 1, pp. 105–112, January–February, 2009.     

Nitrogen and argon solubility in liquid uranium,tungsten, and molybdenum hexafluorides

Experimental data on the solubility of argon and nitrogen in liquid uranium, tungsten, and molybdenum hexafluorides in the temperature interval 20–90°C and gas partial pressure 180–929 kPa are presented. The application of the most common methods of calculating the solubility of gases for the systems studied is discussed.     

Determination of a version of a unit for synchronous cleaning and utilization of gas exhausts from heat generators

Versions for performing synchronous cleaning and utilization of flue gases, calculation schemes and basic equations for defining them, engineering schemes with an indication of the main equipment for these versions, are considered. The possibility is demonstrated of improving the ecological safety of a boiler unit simultaneously with a reduction in discharge of heat into the environment.