Spallation of oxide scales from 20%Cr25%NiNb stainless steel

Bennett, M. J.; Buttle, D.J.; Colledge, P.D; Price, J. B.; Scruby, C. B.; Stacey, Kaye

doi:10.1016/0921-5093(89)90740-5

Cited by 24 publications

(8 citation statements)

References 4 publications

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“…1,2 The relatively weak quartz peak in some spectra and its absence in other spectra suggest that SiO 2 may be present in crystalline quartz form and/or as amorphous silica. [13][14][15] The presence of ferrite/martensite peaks in some samples after oxidation confirms the EBSD results shown above. However, there are difficulties in using the XRD data in Fig.…”

Section: Resultssupporting

confidence: 90%

Surface alloy depletion and martensite formation during glass to metal joining of austenitic stainless steels

Susan

Knorovsky

Robino

et al. 2012

Science and Technology of Welding and Joining

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Preoxidised and glass to metal (GtM) sealed austenitic stainless steels displayed a ferritic (bcc) layer near the metal/oxide interface, as determined by electron backscatter diffraction and X-ray diffraction. Through electron probe microanalysis, it was determined that this layer was depleted of alloying elements due to the oxidation and sealing processes. Characterisation of the layer morphology suggested that it formed through the martensite transformation mechanism. Thermochemical modelling with ThermoCalc also supported a martensitic transformation as opposed to diffusional ferrite formation. The composition gradient through the layer was correlated to the Eichelman and Hull empirical relationship for martensite start (M s ) temperatures. Because of Cr, Mn and Si depletion during preoxidation and glass sealing, M s temperatures near ambient are possible in this surface region. The martensite layer was non-uniform, however, with laths extending deeper into the alloy due to stabilised growth in the material above its M s temperature. This behaviour was characterised by image analysis techniques and discussed in terms of martensite stability and microstructural effects. Possible negative aspects of bcc phase formation on GtM seal properties are discussed, and analyses of alternative alloys 21-6-9 (tradename Nitronic 40; Armco Holding Corp., West Chester, OH, USA) and 22-13-5 (Nitronic 50) showed reduction or elimination of martensite after GtM joining.

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Section: Resultssupporting

confidence: 90%

Surface alloy depletion and martensite formation during glass to metal joining of austenitic stainless steels

Susan

Knorovsky

Robino

et al. 2012

Science and Technology of Welding and Joining

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“…direct ''glass''/metal contact. Amorphous SiO 2 layers formed at the oxide/metal interface during oxidation of stainless steels are well documented [10,16,[29][30][31]. The smooth interfacial characteristics and complete coverage of the alloy surface could be characteristics of amorphous SiO 2 , observed predominantly in nonadherent heats.…”

Section: Discussion Of the Role Of Alloying Elements In Pre-oxidationmentioning

confidence: 95%

The Effects of Pre-Oxidation and Alloy Chemistry of Austenitic Stainless Steels on Glass/Metal Sealing

et al. 2009

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An oxidation treatment is often performed on austenitic stainless steel prior to joining to alkali barium silicate glass to produce hermetic seals. The thin oxide formed during this pre-oxidation step acts as a transitional layer and a source of Cr and other elements that diffuse into the glass during the subsequent bonding process. Pre-oxidation is performed in a low pO 2 atmosphere to avoid iron oxide formation; the final oxide is composed of Cr 2 O 3 , MnCr 2 O 4 spinel, and SiO 2 . Significant heat-to-heat variations in the oxidation behavior of austenitic stainless steel were observed in this work, resulting in inconsistent glass/metal seal behavior. Twenty-five (25) stainless steel heats were examined including 304L, 316L, and experimental high sulfur alloys similar to 303SS. The objectives were to characterize the oxidation kinetics, the oxide morphologies, and compositions that affect glass/ metal adhesion. It was found that poor glass sealing is associated with a more continuous layer of SiO 2 at the metal/oxide interface. The effects of alloy chemistry, in particular Mn and Si concentrations, on glass/metal sealing behavior were empirically determined. A criterion based on the Mn/Si ratio was developed for use in selecting heats with good glass/metal bonding characteristics. To test this criterion, four other austenitic stainless steels were evaluated: 21-6-9 (also known by original Armco Steel Co. trade name Nitronic Ò 40), 22-13-5 (Nitronic Ò 50), Nitronic Ò 60, and Gall-Tough Ò (Carpenter Technology Corp.). These alloys have compositions significantly different from 300-series alloys, but they were still found to comply with the compositional guidelines developed for predicting glass/metal adhesion.

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“…Over the last few decades, several authors have used acoustic emission devices during studies of the high temperature corrosion behavior of metals and alloys, steel sulfidation [18], metal dusting inhibition [19], and alloy oxidation [20]. Since 1977 other authors have coupled acoustic emission with thermogravimetric analysis (TGA) in order to improve understanding of different high temperature corrosion phenomena [21][22][23][24][25]. The sample mass variation and the AE signals are simultaneously recorded during these experiments.…”

Section: Methodsmentioning

confidence: 99%

In situ high temperature oxidation analysis of Zircaloy-4 using acoustic emission coupled with thermogravimetry

Omar

Peres

Serris

et al. 2015

Journal of Nuclear Materials

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h i g h l i g h t sThermogravimetry associated to acoustic emission (AE) improves knowledge on the corrosion of metals at high temperature. Kinetic transition is detected under air oxidation tests at 900°C of Zircaloy-4 by a change in the rate of mass gain and by the AE activity. AE analysis is complementary to characterizations of post mortem oxidized samples. AE allows us to distinguish the cracks which occur during the Zircaloy-4 oxidation from the cracks which arise during the cooling of the samples. a b s t r a c tZircaloy-4 oxidation behavior at high temperature (900°C), which can be reached in case of severe accidental situations in nuclear pressurised water reactor, was studied using acoustic emission analysis coupled with thermogravimetry. Two different atmospheres were used to study the oxidation of Zircaloy-4: (a) helium and pure oxygen, (b) helium and oxygen combined with slight addition of air. The experiments with 20% of oxygen confirm the dependence on oxygen anions diffusion in the oxide scale. Under a mixture of oxygen and air in helium, an acceleration of the corrosion was observed due to the detrimental effect of nitrogen. The kinetic rate increased significantly after a kinetic transition (breakaway). This acceleration was accompanied by an acoustic emission activity. Most of the acoustic emission bursts were recorded after the kinetic transition (post-transition) or during the cooling of the sample. The characteristic features of the acoustic emission signals appear to be correlated with the different populations of cracks and their occurrence in the ZrO 2 layer or in the a-Zr(O) layer. Acoustic events were recorded during the isothermal dwell time at high temperature under air. They were associated with large cracks in the zirconia porous layer. Acoustic events were also recorded during cooling after oxidation tests both under air or oxygen. For the latter, cracks were observed in the oxygen enriched zirconium metal phase and not in the dense zirconia layer after 5 h of oxidation.

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Spallation of oxide scales from 20%Cr25%NiNb stainless steel

Cited by 24 publications

References 4 publications

Surface alloy depletion and martensite formation during glass to metal joining of austenitic stainless steels

Surface alloy depletion and martensite formation during glass to metal joining of austenitic stainless steels

The Effects of Pre-Oxidation and Alloy Chemistry of Austenitic Stainless Steels on Glass/Metal Sealing

In situ high temperature oxidation analysis of Zircaloy-4 using acoustic emission coupled with thermogravimetry

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