Influence of High Temperature Oxidation on Hydrogen Absorption and Degradation of Zircaloy-2 and Zr 700 Alloys

Zieliński, Andrzej; Cymann, Anita; Gumiński, Adrian; Hernik, Anna; Gajowiec, Grzegorz

doi:10.1515/htmp-2017-0074

Cited by 3 publications

(5 citation statements)

References 32 publications

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“…The applied cathodic charging has been already used several times [22][23][24][25][26] and may result in the hydrogenation of Zr alloys even at room temperature after further annealing. The hydrogen content in these tests was not measured, but it should be close to the values given for similar alloys in our earlier research [27]. Such hydrogen content is certainly above the limit hydrogen solubility value at room temperature.…”

Section: Effect Of Oxide Layer On Hydrogen Absorption and Degradationsupporting

confidence: 86%

Oxidation and Hydrogen Behaviur in Zr-2Mn Alloy

Zienkiewicz

Paradowska

Serbiński

et al. 2018

Advances in Materials Science

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The purpose of the present research was to determine the oxidation and hydrogenation behavior in the new Zr-2Mn alloy. The oxidation of alloy was performed at temperatures between 350°C and 900°C for 30 minutes. The hydrogen charging was made for 72 h at a current density 80 mA/cm 2 . The charged samples were heat treated at 400°C for 4 h to obtain a uniform hydrogen profile content across the sample. The oxidation resulted in an appearance of non-uniform oxide layers of thickness increasing with temperature. The surface damage was observed at higher temperatures 700 and 900°C. After charging with hydrogen followed by annealing no hydrides were found. The observed effect is evidence that the oxide layers may form effective barriers against hydrogen diffusion even if they are partially degraded. The absence of hydrides or hydride cracking may be caused by an absence in Zr-Mn alloys of such phase precipitates, which may trap diffusive hydrogen and initiate the hydrides. The positive influence of manganese on the formation of the thick oxide layer and relative resistance to delayed hydride cracking may be attributed to its affinity of oxygen, the ability to form thick and compact oxide layers during oxidation, the formation of solid solution in zirconium and no precipitates enhancing nucleation of hydrides.

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Section: Effect Of Oxide Layer On Hydrogen Absorption and Degradationsupporting

confidence: 86%

Oxidation and Hydrogen Behaviur in Zr-2Mn Alloy

Zienkiewicz

Paradowska

Serbiński

et al. 2018

Advances in Materials Science

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“…Every specimen in this study possessed the crack or multiple cracks on the top of a bulge. The descaling, again much more intensive on the outer surface, is an obvious consequence of developing cracking as already observed [29].…”

Section: Oxidation At 1273 Ksupporting

confidence: 68%

“…The oxide layers possess small columnar grains and equiaxed grains [4]. The cracking of oxide layers at relatively low oxidation temperature was often observed [29,30]. The cracking of the oxide layer was explained by the accumulation of compressive stresses in the oxide at the interface in pre-transition stage, resulting from imperfect accommodation of the volume expansion attendant upon oxide formation [2].…”

Section: Oxidation At 1273 Kmentioning

confidence: 99%

X-Ray Computer Tomography Study of Degradation of the Zircaloy-2 Tubes Oxidized at High Temperatures

Trybuś

Olivé

Lenoir

et al. 2019

Advances in Materials Science

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The investigations of high-temperature oxidation of zirconium alloys, applied for fuel pellets in nuclear power plants, are usually limited to oxidation kinetics, phase transformations and microstructural characterization. The purpose of this research was to characterize the degradation phenomena occurring within oxide layer and at the interface oxide/metal, on internal and external Zircaloy-2 tube surfaces, below and over crystalline transformation temperature of zirconium oxides. The commercial tubes were oxidized at 1273 K and 1373 K in calm air for 30 min and then examined with a technique novel for such purpose, namely a high-resolution X-ray computer tomography. The light microscopy was used to examine the cross-surfaces. The obtained results show that the form and intensity of oxide damage is significant and it is in a complicated way related to oxidation temperature and on whether external or internal tube surface is studied. The found oxide layer damage forms include surface cracks, the detachment of oxide layers, the appearance of voids, and nodular corrosion. The oxidation effects and damage appearance are discussed taking into account the processes such as formation of oxides, their phase transformation, stress-enhanced formation and propagation of cracks, diffusion of vacancies, formation of nitrides, diffusion of hydrogen into interface oxide-metal, incubation of cracks on second phase precipitates are taken into account to explain the observed phenomena.

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“…The width of the oxide layer was the largest near the cracks. The previously performed monitoring of oxidation time [60] showed that after oxidation at 900 • C, the cracks appeared on the surface already after 20 min of oxidation and were relatively long, even up to 35 µm. The oxide layer was substantially thicker in this area.…”

Section: Methodsmentioning

confidence: 95%

“…Despite this knowledge, the influence of the oxide layer characteristics on hydrogen absorption was not often investigated. The applied cathodic charging in cold or heated electrolytes was already utilized [14,20,38,50,56,57,60,[84][85][86][87], resulting in the appearance of hydrogen within a thin subsurface layer, mainly as the hydrides and saturated or oversaturated hydrogen interstitial solution. The further annealing (here called homogenizing heat treatment) resulted in a uniform hydrogen concentration.…”

Section: Barrier Effect Of the Oxide Layermentioning

confidence: 99%

Hydrogen Embrittlement and Oxide Layer Effect in the Cathodically Charged Zircaloy-2

et al. 2020

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The present paper is aimed at determining the less investigated effects of hydrogen uptake on the microstructure and the mechanical behavior of the oxidized Zircaloy-2 alloy. The specimens were oxidized and charged with hydrogen. The different oxidation temperatures and cathodic current densities were applied. The scanning electron microscopy, X-ray electron diffraction spectroscopy, hydrogen absorption assessment, tensile, and nanoindentation tests were performed. At low oxidation temperatures, an appearance of numerous hydrides and cracks, and a slight change of mechanical properties were noticed. At high-temperature oxidation, the oxide layer prevented the hydrogen deterioration of the alloy. For nonoxidized samples, charged at different current density, nanoindentation tests showed that both hardness and Young’s modulus revealed the minims at specific current value and the stepwise decrease in hardness during hydrogen desorption. The obtained results are explained by the barrier effect of the oxide layer against hydrogen uptake, softening due to the interaction of hydrogen and dislocations nucleated by indentation test, and hardening caused by the decomposition of hydrides. The last phenomena may appear together and result in hydrogen embrittlement in forms of simultaneous hydrogen-enhanced localized plasticity and delayed hydride cracking.

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Influence of High Temperature Oxidation on Hydrogen Absorption and Degradation of Zircaloy-2 and Zr 700 Alloys

Cited by 3 publications

References 32 publications

Oxidation and Hydrogen Behaviur in Zr-2Mn Alloy

Oxidation and Hydrogen Behaviur in Zr-2Mn Alloy

X-Ray Computer Tomography Study of Degradation of the Zircaloy-2 Tubes Oxidized at High Temperatures

Hydrogen Embrittlement and Oxide Layer Effect in the Cathodically Charged Zircaloy-2

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