Quantitative Analysis of Structural Changes in Steel Caused by High-Temperature Holding in Hydrogen

We give a quantitative estimate of changes in the structure of 15Kh2MFA steel after its long-term exposure to the combined action of high temperature, tensile stresses, and hydrogen as the factors of degradation of this steel under conditions of oil hydrocracking. Under laboratory conditions, we study the effect of high-temperature hydrogen degradation of 15Kh2MFA heat-resistant steel on changes in the quantitative characteristics of its structural elements, in particular, in the dimension and average distance between carbides as well as in their orientation from one grain to another. Algorithms for the solution of the formulated problems are described, and the possibilities of proposed approaches for the quantitative automatic processing of metallographic images are shown.     

Problem of unity of measurements in ensuring safety of hydraulic structures

Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 1, pp. 14–17, January, 1994.     

Initiation of detonation in hydrogen—Air mixture by explosion of a spherical TNT charge

Direct initiation of detonation by explosion of a TNT charge in a hydrogen—air mixture is considered. The critical mass of initiating charge is determined numerically using a finite-difference method based on the Godunov scheme, taking into account the real chemical kinetics of combustion of hydrogen in air and the real equation of state for gaseous detonation products of TNT. The applicability of the equation of state of a perfect gas to the detonation products of TNT is considered. The effective value of the exponent of Poisson's adiabat is determined.Moscow. Translated from Fizika Goreniya i Vzryva, Vol. 31, No. 2, pp. 91–95, March–April, 1995.     

Unsteady laminar gas flows in an annular nozzle

On the basis of the Navier–Stokes equations, a parametric study of the influence of various factors on the development of initial perturbations caused by starting an air-blown annular nozzle is performed for the laminar model of flow. Flow regimes are found in which the start perturbations accompanying the initiation of the nozzle do not attenuate but pass to a quasi-periodic mode. The frequency Fourier spectrum of pressure fluctuations at the center of the thrust wall and the value of the thrust of the nozzle are determined. Typical pulsed pressure signals obtained in the calculation model and detected in the experiments are presented.     

Corrosion-Mechanical Strength of Structural Materials in Contact with Liquid Lead

Corrosion-mechanical tests of 10Kh15N9S3B and 10Kh9NSMFB steel samples in liquid lead at 360–550°C have shown that the long-time strength in lead flow decreases at short times to fracture and converges to the results of tests performed in air at about 10000 h. No liquid-metal embrittlement of 10Kh15N9C3B steel is observed. 10Kh9NSMFB steel becomes brittle in the hardened state. Embrittlement intensifies in notched samples. The low-cycle fatigue strength is correlated with a change in ductility with short-time fracture. No decrease of fracture toughness of 10Kh9NSMFB steel with a fatigue crack was observed in tests in liquid lead.     

Discrete positions method in kinematics and control of spatial linkagesEine methode der diskreten lagen in der kinematik und steuerung der bewegungen raumlicher mechanismen

Using the screw theory in the field of infinitesimal displacements, the first and second order transfer functions of spatial kinematic chains are algebrised. Based on this, a method of finite increments of the relative displacements in the joints is offered. Finally, an algorithm for the control strategy of open kinematic chains of manipulators and robots was evolved using an imaginary closing of the kinematic chain while bearing in mind the conditions for instantaneous mobility (transitory).