TEM CHARACTERIZATION OF A FUSION ZONE IN P23/P91 WELDS

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61989100%3A27360%2F17%3A10238304" target="_blank" >RIV/61989100:27360/17:10238304 - isvavai.cz</a>

Výsledek na webu

<a href="https://www.metalconference.eu/files/uploads/02/METAL2017_conference_proceedings_content.pdf" target="_blank" >https://www.metalconference.eu/files/uploads/02/METAL2017_conference_proceedings_content.pdf</a>

DOI - Digital Object Identifier

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Jazyk výsledku

angličtina

Název v původním jazyce

TEM CHARACTERIZATION OF A FUSION ZONE IN P23/P91 WELDS

Popis výsledku v původním jazyce

Dissimilar welds are widely used in tubular systems of power plant boilers to compensate for different operating conditions. Redistribution of interstitial elements across the fusion line is regarded to be the most dangerous degradation mechanism in heterogeneous welds. Carbon and nitrogen move along the gradient of their chemical potential, in our case from P23 steel towards P91 steel. The paper deals with a TEM characterization of precipitation processes in fusion zones of two variants of heterogeneous P23/P91 welds after creep tests at 550oC with times to rupture up to ca 80 000 hours. Both carbon extraction replicas and thin foils were studied. In carburized areas of welds heavy precipitation of carbides was observed, most of them corresponded to M23C6 carbides. The Cr/Fe ratio in these carbides continuously and systematically changed from the onset of carburized areas towards WM91 or P91 base material. This proved that carburization started in fusion zones, characterized by a continuous gradient of chemical composition. Furthermore, a low fraction of M6X particles occurred in carburized areas. In adjacent partly decarburized areas of WM23 or P23 steel M23C6 and M7C3 particles dissolved during creep at 550oC. Furthermore, SAED investigations revealed precipitation of Laves phase of Fe2W type in partly decarburized areas of both variants of P23/P91 welds. Precipitation of Laves phase has not been reported in P23 steel yet. Thermodynamic calculations proved that a reduction of carbon content in partly decarburized areas of WM23 or P23 steel made it possible to stabilize this minor phase.

Název v anglickém jazyce

TEM CHARACTERIZATION OF A FUSION ZONE IN P23/P91 WELDS

Popis výsledku anglicky

Dissimilar welds are widely used in tubular systems of power plant boilers to compensate for different operating conditions. Redistribution of interstitial elements across the fusion line is regarded to be the most dangerous degradation mechanism in heterogeneous welds. Carbon and nitrogen move along the gradient of their chemical potential, in our case from P23 steel towards P91 steel. The paper deals with a TEM characterization of precipitation processes in fusion zones of two variants of heterogeneous P23/P91 welds after creep tests at 550oC with times to rupture up to ca 80 000 hours. Both carbon extraction replicas and thin foils were studied. In carburized areas of welds heavy precipitation of carbides was observed, most of them corresponded to M23C6 carbides. The Cr/Fe ratio in these carbides continuously and systematically changed from the onset of carburized areas towards WM91 or P91 base material. This proved that carburization started in fusion zones, characterized by a continuous gradient of chemical composition. Furthermore, a low fraction of M6X particles occurred in carburized areas. In adjacent partly decarburized areas of WM23 or P23 steel M23C6 and M7C3 particles dissolved during creep at 550oC. Furthermore, SAED investigations revealed precipitation of Laves phase of Fe2W type in partly decarburized areas of both variants of P23/P91 welds. Precipitation of Laves phase has not been reported in P23 steel yet. Thermodynamic calculations proved that a reduction of carbon content in partly decarburized areas of WM23 or P23 steel made it possible to stabilize this minor phase.

Druh

D - Stať ve sborníku

CEP obor

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OECD FORD obor

20501 - Materials engineering

Projekt

<a href="/cs/project/LO1203" target="_blank" >LO1203: Regionální materiálově technologické výzkumné centrum - Program udržitelnosti</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2017

Kód důvěrnosti údajů

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

Název statě ve sborníku

METAL 2017: conference proceedings : 26th International Conference on Metallurgy and Materials : (reviewed version) : May 24th-26th 2017, Hotel Voroněž I, Brno, Czech Republic, EU

ISBN

978-80-87294-79-6

ISSN

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e-ISSN

neuvedeno

Počet stran výsledku

6

Strana od-do

"666 "- 671

Název nakladatele

Tanger

Místo vydání

Ostrava

Místo konání akce

Brno

Datum konání akce

24. 5. 2017

Typ akce podle státní příslušnosti

WRD - Celosvětová akce

Kód UT WoS článku

000434346900103