Prediction of chromium depleted-zone evolution during aging of Ni–Cr–Fe alloys

Sahlaoui, Habib; Sidhom, Habib; Philibert, J.

doi:10.1016/s1359-6454(01)00444-x

Cited by 97 publications

(64 citation statements)

References 16 publications

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“…All of the models for sensitisation, 3,4,[7][8][9] only consider grain-boundary precipitation, which always happen at the very early stage of ageing. This can be sufficient, as illustrated previously, to predict the onset of sensitisation.…”

Section: The Significance Of Dmentioning

confidence: 99%

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Sensitisation and Evolution of Chromium-depleted Zones in Fe-Cr-Ni-C Systems

2003

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The development of chromium concentration profiles in austenitic stainless steels, due to the grain boundary precipitation of carbides has been modelled, taking account of multicomponent effects, both in the estimation of the state of equilibrium at the carbide/matrix interface and in diffusion. A comparison against published experimental data shows that the theory accounts for the development of the depleted zone as well as self-healing, unlike recent work where these effects are treated as separate phenomena. At the same time, the present model preserves local equilibrium at the precipitate-matrix interface and provides a natural explanation for the observation of delays in reaching the minimum chromium content.

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Section: The Significance Of Dmentioning

confidence: 99%

“…Sahlaoui et al 8) recently developed a different approach based on Mayo 9) where the process is divided into two. where t is time to reach minimum c Cr gb , t is time and k is a constant.…”

Section: Introductionmentioning

confidence: 99%

Sensitisation and Evolution of Chromium-depleted Zones in Fe-Cr-Ni-C Systems

2003

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“…Therefore, has to consume Cr nearby grain boundary. This causes poor Cr area of grain boundary [13]. Cr content value of poor Cr area is far below the limit value of passivation needed, its potential is lower than grain's internal potential, much lower than the precipitated phase of grain boundary.…”

Section: Intergranular Corrosion Experimentsmentioning

confidence: 99%

“…δ phase is dissolved because can't form passivation film and presents the glacier surface. Carbide precipitated in grain boundary and intermetallic in the corrosion process are also dissolved because electric potential is lower than the grain interior pare, as shown in with alloy element diffusion [13]. With the extension of aging time, after aging for 200h, needle-like δ phase generates which can't form passivation film [10].…”

Section: Intergranular Corrosion Experimentsmentioning

confidence: 99%

“…With aging sensitization time change, can be described by Johnson-Mehl-Avrami equation, i.e. : dilution area cause intergranular corrosion tendency [11][12][13][14]. Pay attention to alloy's mechanics and anti-corrosion property's change during aging process can increase structure's stability, which is an effective way to prolong high-temperature components' life.…”

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Long Term Aging Treatment Impact on Ultralow Iron Alloy 625 Intergranular Corrosion Property

Zhu¹,

Sui²,

Dai³

et al. 2017

Preprint

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This paper investigates the evolution of microstructures and precipitations of an ultra-low iron alloy 625 subjected to long term aging treatment by scanning electron microscope (SEM) and X-ray diffraction(XRD). Use ASTM G28A acid Fe3(SO4)2 erosion to represent intergranular corrosion weightlessness and corrosive morphology. The result shows that alloy at 750°C by aging treatment for 40h, precipitated γ'' phase in the grain boundary. In high density area of γ'' phase, occurs γ'' phase to δ phase degeneration transformation by aging treatment for 200h and the needle-like δ phase becomes more with time prolonged. And γ'' phase degenerated to δ phase completely until treated for 1000h. The sample which has aging treatment tends to have intergranular corrosion and mainly because alloy element spreading leads to dilution area and grain boundary precipitated phase, plus interlaced δ phase's dissolving, which makes sample grain particle fall off and this results in apparent weightlessness. The weightlessness rate(WLR) is related with precipitated volume score. With aging sensitization time change, can be described by Johnson-Mehl-Avrami equation, i.e.: = 44.32 1 − exp (− . ) + 44.62 1 − exp (− . ) + 1.267 ( / ).

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