Nature of defects near the boundary and their role in corrosion cracking of aluminum alloys

Kurtasova, L. A.; Polyanskii, V. M.

doi:10.1007/bf00722662

Cited by 2 publications

(3 citation statements)

References 5 publications

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“…Unlike [ 19,20], where the partial pressure of hydrogen was assumed to be independent of the radius of microvoids, this factor is taken into account in relation (8) (Fig. At the same time, this estimate is more moderate than that proposed in [14,15]: At the same time, this estimate is more moderate than that proposed in [14,15]:…”

Section: Evaluation Of the Pressure Of Methane Under The Assumption Tmentioning

confidence: 88%

“…On the basis of the thermodynamic analysis of a two-phase (metalmicrovoid) system containing hydrogen and Me3C, Me7C 3 , and Me~3C6-type carbides as thermodynamic components, we suggest a new scheme for the evaluation of the partial pressure of methane in the microvoids of the metal. It accelerates self-diffusion in the material [9], intensifies the ability of dislocations to move [ 10,11], and induces high internal pressures inside microvoids [12][13][14][15][16]. Unlike the previous computational schemes, in the proposed scheme, pressure depends on the radius of the microvoid.…”

mentioning

confidence: 99%

“…It accelerates self-diffusion in the material [9], intensifies the ability of dislocations to move [ 10,11], and induces high internal pressures inside microvoids [12][13][14][15][16]. It accelerates self-diffusion in the material [9], intensifies the ability of dislocations to move [ 10,11], and induces high internal pressures inside microvoids [12][13][14][15][16].…”

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confidence: 99%

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Analytic evaluation of the pressure of methane in microvoids of 2.25Cr-1Mo steel subjected to hydrogen attack

Nykyforchyn¹,

Skrypnyk²,

Didukh³

1998

Mater Sci

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We present an estimate of the partial pressure of methane in microvoids under the conditions of hydrogen corrosion in 2.25Cr-1Mo steel. On the basis of the thermodynamic analysis of a two-phase (metalmicrovoid) system containing hydrogen and Me3C, Me7C 3 , and Me~3C6-type carbides as thermodynamic components, we suggest a new scheme for the evaluation of the partial pressure of methane in the microvoids of the metal. We give an example of the evaluation of the pressure of methane in internal cavities in steel at a temperature of 500"C for a simplified case where the formation of methane is controlled by the amount of carbon formed as a result of the decomposition of carbides. Unlike the previous computational schemes, in the proposed scheme, pressure depends on the radius of the microvoid. In the general case, this approach also takes into account the distance between the analyzed layer and the metal surface, the width of the decarbonized zone, the rates of carbon and hydrogen diffusion in the metal, and many other parameters.High-temperature degradation of heat-resistant and moderately alloyed steels used in chemical, oil-refining, and power-plant industry is caused by the nucleation and growth of microvoids along grain boundaries. As a result of merging, microvoids form intergranular cracks, which lead to failures. Intergranular degradation does not cause any visible unrecoverable deformation in the material because only a small part of the material near grain boundaries undergoes changes. Therefore, it is hardly possible to evaluate the level of degradation of the material by analyzing the deformation of creep acquired by the material. In this case, one must give attention to metallographic analysis and analytic methods for modeling and failure prediction.The localization of high-temperature degradation processes is explained by the action of the mechanisms of deformation and damage (i.e., micromechanisms of grain-boundary diffusion [ 1, 2]) predominant in the temperature and stress ranges typical of the actual operating conditions, i.e., for ~ = 10-102 MPa and T = 400-600~ These parameters are too low to induce creep in the bulk of the material but they are sufficiently high to induce the nucleation of vacancies on the grain boundaries as a result of slip of the boundary dislocations [3,4]. Since, under these conditions, vacancy diffusion along grain boundaries is more intense than diffusion in the bulk of the material [2], the newly formed vacancies diffuse to microvoids, which grow due to the accumulation of vacancies. The inadequacy of the power-creep mechanism under these conditions means that viscous flows are absent in the material. This enables us to reduce the problem of simulation of the growth of grain-boundary voids to the solution of a onedimensional boundary-value diffusion problem. The importance of this problem inspired the appearance of numerous works in this direction [5][6][7][8].The phenomenon of high-temperature degradation becomes even more complicated if hydrogen is present in the materi...

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Section: Evaluation Of the Pressure Of Methane Under The Assumption Tmentioning

confidence: 88%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Analytic evaluation of the pressure of methane in microvoids of 2.25Cr-1Mo steel subjected to hydrogen attack

Nykyforchyn¹,

Skrypnyk²,

Didukh³

1998

Mater Sci

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Influence of the density of grain boundary precipitates and factors related to it on the corrosion cracking resistance of Al-Zn-Mg and Al-Zn-Mg-Cu system alloys

Burmistrova¹,

Polyanskii²

1984

Mater Sci

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Nature of defects near the boundary and their role in corrosion cracking of aluminum alloys

Cited by 2 publications

References 5 publications

Analytic evaluation of the pressure of methane in microvoids of 2.25Cr-1Mo steel subjected to hydrogen attack

Analytic evaluation of the pressure of methane in microvoids of 2.25Cr-1Mo steel subjected to hydrogen attack

Influence of the density of grain boundary precipitates and factors related to it on the corrosion cracking resistance of Al-Zn-Mg and Al-Zn-Mg-Cu system alloys

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