Investigations of the influence of hydrogen on metals carried out in the karpenko physicomechanical institute

Pokhmurs'kyi, V. I.

doi:10.1007/bf02537541

Cited by 7 publications

(3 citation statements)

References 16 publications

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“…The experimental points fall of from calculated once to 0.6µm to roughness increasing. Nevertheless an increasing of a surface finish is observed and that is essentially important for the short time period of machining (within 4-5 minutes of machining in the case of combined machining application the roughness decreases from 7 to 2.5 -3.0 µm) [15]. Materials Engineering and Technologies for Production and Processing VI If proceed from the necessity to achieve the roughness stipulated in Design Documentation, than the combined machining allows approximately twice to reduce technological cycle.…”

Section: Solid State Phenomena Vol 316mentioning

confidence: 99%

Influence of Contact Efforts on the Surface Quality of Difficult Profile under Finishing Hardening Machining

Сухочев

Sokolnikov

Nekrylov

2021

SSP

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This work presents the research and development data in the field of finishing and hardening processes for parts with complicated shape surface. The comparable effectiveness of different surface finishing and hardening processes were studied, and intensification possibilities of processes of vibration finishing - hardening machining of narrow ducts by means of combined methods with metal anodic dissolution were shown. The results of experimental researches of influence of extrusion conditions of granular media on the surface layer quality are presented.

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Section: Solid State Phenomena Vol 316mentioning

confidence: 99%

Influence of Contact Efforts on the Surface Quality of Difficult Profile under Finishing Hardening Machining

Сухочев

Sokolnikov

Nekrylov

2021

SSP

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“…It is known that the presence of hydrogen in the metal increases the creep rate [18] and diffusivity [19] by an order of magnitude. Thus, even a small increase in the level of stresses inside the pipe wall results in a significant acceleration of crack growth caused both by the direct influence of the stress factor and an increase in the concentration of hydrogen (with subsequent increase in the creep rate).…”

Section: )~ Dt Tmentioning

confidence: 99%

Distinctive features of fatigue crack growth in 14Mo V63 pipe steel after service

Student¹,

Sijacki-Zeravcic²,

Skrypnyk³

et al. 1999

Mater Sci

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We study the influence of technological parameters of operation of the bends of steam pipelines made of 14MoV63 steel on the kinetic characteristics of fatigue crack growth. We show that an increase in the steam pressure in the pipeline determining the stress-strain state of the pipe wall promotes a decrease in the threshold characteristics of crack resistance. The tests carried out for the constant range of the stress intensity factor revealed the acceleration of crack growth in internal layers of the pipe wall for the metal operating under higher service steam pressure and near the external surface of the metal operating under lower service pressure. We propose a mathematical model of growth of grain-boundary cracks at high temperatures. It is assumed that the crack propagates by the mechanism of merging of pores ahead of the crack tip. The appearance and growth of these pores are governed by the vacancy mechanism.The characteristics of serviceability of steam pipelines of power plants are determined by the resistance of their material to high-temperature degradation, which depends, first, on the temperature-force service parameters [1,2] and, second, on the aggressive action of the working media [3]. The stresses are induced in the pipe walls by numerous factors, including the inner pressure and weight of the working media, the weight of the pipeline and elements connected to it, the nonuniformity of temperature fields, the cyclic character of loading, etc. The most harmful conditions occur near the pipe bends due to the specific stress-strain state and the difference in the geometry of the pipe section [2].It is known that the microstructure and mechanical properties of the metals, including the characteristics of static and cyclic crack growth resistance, vary during long-term service of pipelines [l, 4-6]. In [5,6], it is indicated that the threshold parameters of fatigue crack growth are sensitive to the degradation of steels. The present work deals with the development of the results of investigations carried out in [5][6][7] with an aim to apply a fatigue approach of fracture mechanics to the evaluation of the degree of degradation of the bent parts of pipelines taking into account the time-force service parameters.

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“…For the diffusion coefficient, we take the Arrhenius dependence [18] on the averaged temperature of the hydrophitic zone, which is calculated using the heat conduction equation with friction. The initial distribution of hydrogen in the body and the functional time dependence of the surface concentration of hydrogen are simulated, respectively, by the functions q)(x) and ~ (t) (Fig.…”

Section: )mentioning

confidence: 99%

Features of simulation of a hydrophilic zone with regard for hydrogen wear in the process of friction

Shyrokov¹,

Koval'chyk²

1998

Mater Sci

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By analyzing peculiarities of the phenomenon of hydrogen wear, in particular, the formation of a hydrophilic zone, we present approaches to its simulation for subsurface layers of metal by using mathematical models developed earlier by the authors.The phenomenon of hydrogen wear is a complex of thermodynamically low-probability physicochemical processes caused by friction. The main processes are liberation of hydrogen from the environment, its passage through the surface of a metallic counterbody, and specific fracture of surface layers.For a long time, it was impossible to explain or predict this phenomenon on the basis of the known theoretical concepts. Indeed, up to the middle 70s, wear was considered as a superposition of two simultaneous processes (rubbing out and crumpling) [ 1 ]. Moreover, by rubbing out and crumpling, one meant, respectively, the process of separation or cutting of particles followed by their subsequent removal from the friction zone and a decrease in a linear size due to flattening which occurs without loss of mass. Since the repetition of deformation was not taken into account, a question on the influence of hydrogen on fracture of surface layers of metal did not arise because it does not manifest itself under single loading. It is known that hydrogen is liberated from metals in the process of heating of steel components. Since heat is emitted in the process of friction, it seems quite natural to admit dehydrogenation of metal instead of hydrogenation that was shown further in [2,3]. The question of sources of hydrogen remained open. Despite the fact that tribodestruction of organic lubricant-cooling media and other media was regarded, in general, as possible under friction, the cause-effect connection such as "hydrogen-wear" was not considered for service of machines. At the same time, the analysis of actual facts and displays of hydrogen wear indicates the danger and large-scale character of this phenomenon (see Table 1) [4][5][6].Comparison of facts concerning the liberation of hydrogen in the process of friction, an increase in wear of a surface under hydrogenation, and paradoxical fracture of a solid surface of products made of steels, cast irons, and titanium, which operate together with soft plastic materials and some other ones, led to a problem of factors characterizing hydrogen wear in a wide range of friction conditions.A comprehensive analysis of data on hydrogen wear allows one to state the following:--the phenomenon requires complex approaches in the frameworks of mechanics, physics, and chemistry;--a particular hydrophilic state of the subsurface layer formed during friction with an increased concentration of hydrogen, which could be greater than its bulk concentration by one order, is observed;--two forms of cyclic (fatigue) fracture of steel during friction are established which were not encountered in investigations of hydrogen brittleness, namely, instantaneous total fracture of the surface layer and its slow dispersion;--neither sources of hydrogenation nor moving fo...

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Investigations of the influence of hydrogen on metals carried out in the karpenko physicomechanical institute

Cited by 7 publications

References 16 publications

Influence of Contact Efforts on the Surface Quality of Difficult Profile under Finishing Hardening Machining

Influence of Contact Efforts on the Surface Quality of Difficult Profile under Finishing Hardening Machining

Distinctive features of fatigue crack growth in 14Mo V63 pipe steel after service

Features of simulation of a hydrophilic zone with regard for hydrogen wear in the process of friction

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