Andriy Sorochak

Degradation of the main gas pipeline material and mechanisms of its fracture

AbstractThe effect of the in-service scattered damage in the pipe wall metal is evaluated, and the effect of hydrogen absorbed by metal on the variation of the structure and mechanical properties of the main gas pipeline after a long-term operation is found. The main regularities in the graded nature of the static deformation process and the effect of hydrogenation on the scattered damage and fracture accumulation are found.

Stereoscopic Analysis of the Stretch Zone of a Steel Specimen Cut Out of a Railway Axle and Tested for Static Fracture Toughness

The method for determining the height of the surface microirregularities by means of a pseudostereopair, which can be used to determine the geometry of the start zone of the brittle separation crack, is completed and automated. The possibility of using the proposed method for investigating the stretch zone of compact specimens of the OSL steel is considered. The stretch zone of the railway axis steel is investigated using the proposed technique.

Modelling Kinetics of Dynamic Crack Propagation in a Gas Mains Pipe as Cyclic Random Process

The approach to the mathematical analysis of fracture toughness of the gas mains steel is proposed, which allows obtaining informative features of the quantitative evaluation of the dynamic pipe fracture kinetics, taking into account the stochastic and cyclic nature of the process. It creates the possibility to model the kinetics of crack propagation in the gas mains pipe and analyzing individual stages of its growth.

Cyclic Fracture Toughness of Railway Axle and Mechanisms of Its Fatigue Fracture

Abstract The main regularities in fatigue fracture of the railway axle material - the OSL steel - are found in this paper. Micromechanisms of fatigue crack propagation are described and systematized, and a physical-mechanical interpretation of the relief morphology at different stages of crack propagation is proposed for fatigue cracks in specimens cut out of the surface, internal and central layers of the axle.

Effect of Load Ratio on Fatigue Failure Micromechanisms of Railway Axle Steel

The paper presents the basic regularities of fatigue failure of the railway wheelset axle material – OsL steel (C - 0,40—0,48 %; Mn - 0,55—0,85 %; Si - 0,15—0,35 %; P < 0,04%; S < 0,045 %; Cr < 0,3 %; Ni < 0,3 %; Cu < 0,25 %). It was revealed that under loading stress ratio R = 0, fatigue crack growth is 2 ... 4 times lower than that at the asymmetry R = -1. In doing so, amplitude of stress intensity factor vary in the range of 20 – 35 MPa√m. The micromechanisms of fatigue crack growth are described and systematized, while physical-mechanical interpretations of the relief morphology at different stages of its growth are offered.