Some Effects of Surface Finish and LWR Environment on Environmentally-assisted Crack Initiation in Alloy 182

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F26722445%3A_____%2F22%3AN0000138" target="_blank" >RIV/26722445:_____/22:N0000138 - isvavai.cz</a>

Výsledek na webu

<a href="https://store.ampp.org/some-effects-of-surface-finish-and-lwr-environment-on-environmentally-assisted-crack-initiation-in-alloy-182" target="_blank" >https://store.ampp.org/some-effects-of-surface-finish-and-lwr-environment-on-environmentally-assisted-crack-initiation-in-alloy-182</a>

DOI - Digital Object Identifier

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Jazyk výsledku

angličtina

Název v původním jazyce

Some Effects of Surface Finish and LWR Environment on Environmentally-assisted Crack Initiation in Alloy 182

Popis výsledku v původním jazyce

Within the European Commission funded project MEACTOS, environmentally-assisted crack (EAC) initiation of Alloy 182 was addressed by performing constant extension rate tensile (CERT) and constant load (CL) testing of flat, tapered tensile specimens in both boiling water reactor (BWR) normal water chemistry (NWC) and pressurized water reactor (PWR) primary water environment. Four surface finishes were investigated, namely: ground which serves as reference (RS), industrial face-milled (STI), advanced-machined (SAM) and two shot peened conditions (SP, initial and later). After testing the critical stress for initiating a crack was derived by locating the critical section (the border between areas showing and not showing surface cracking after testing) and calculating the associated local stress. In a first analysis of the CERT results, the critical stress was plotted against the nominal strain rate (cross-head displacement rate divided by the length of the tapered gauge section) and an exponential curve was fitted to it; yielding a characteristic critical stress (extrapolation to zero nominal strain rate) and a characteristic nominal strain rate (rendering the nominal strain rate dimensionless under the exponent). In a second analysis of the CERT results, an initiation model, which is strain rate and stress level dependent, was fitted to obtain a usage towards EAC initiation of 1 in the experimentally-determined critical cross section. CL testing was performed under the same and accelerated test conditions, achieved by increasing temperature and changing test environment. The overall conclusion is that (1) EAC initiation performance is better in the BWR/NWC than in the PWR environment, (2) effects of surface finish are more clearly visible in the PWR environment, (3) EAC initiation performance is better for SAM than for RS or STI which are similar and in turn better than the original SP. A “higher quality” SP surface showed an improvement in EAC initiation performance and this correlated well with the lower surface hardness measured for the latter meaning that hardness could be used as a measure for the quality of surface treatments in respect of EAC initiation. Presented at the 20th International Conference on Environmental Degradation of Materials in Nuclear Power Systems-Water Reactor, 17-21 Jul 2022.

Název v anglickém jazyce

Some Effects of Surface Finish and LWR Environment on Environmentally-assisted Crack Initiation in Alloy 182

Popis výsledku anglicky

Within the European Commission funded project MEACTOS, environmentally-assisted crack (EAC) initiation of Alloy 182 was addressed by performing constant extension rate tensile (CERT) and constant load (CL) testing of flat, tapered tensile specimens in both boiling water reactor (BWR) normal water chemistry (NWC) and pressurized water reactor (PWR) primary water environment. Four surface finishes were investigated, namely: ground which serves as reference (RS), industrial face-milled (STI), advanced-machined (SAM) and two shot peened conditions (SP, initial and later). After testing the critical stress for initiating a crack was derived by locating the critical section (the border between areas showing and not showing surface cracking after testing) and calculating the associated local stress. In a first analysis of the CERT results, the critical stress was plotted against the nominal strain rate (cross-head displacement rate divided by the length of the tapered gauge section) and an exponential curve was fitted to it; yielding a characteristic critical stress (extrapolation to zero nominal strain rate) and a characteristic nominal strain rate (rendering the nominal strain rate dimensionless under the exponent). In a second analysis of the CERT results, an initiation model, which is strain rate and stress level dependent, was fitted to obtain a usage towards EAC initiation of 1 in the experimentally-determined critical cross section. CL testing was performed under the same and accelerated test conditions, achieved by increasing temperature and changing test environment. The overall conclusion is that (1) EAC initiation performance is better in the BWR/NWC than in the PWR environment, (2) effects of surface finish are more clearly visible in the PWR environment, (3) EAC initiation performance is better for SAM than for RS or STI which are similar and in turn better than the original SP. A “higher quality” SP surface showed an improvement in EAC initiation performance and this correlated well with the lower surface hardness measured for the latter meaning that hardness could be used as a measure for the quality of surface treatments in respect of EAC initiation. Presented at the 20th International Conference on Environmental Degradation of Materials in Nuclear Power Systems-Water Reactor, 17-21 Jul 2022.

Druh

O - Ostatní výsledky

CEP obor

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OECD FORD obor

20501 - Materials engineering

Projekt

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Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2022

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů