Impact of Critical Average Size of Second Phases on Microstructure Stability in Homogeneous Weld Joint Made of X6Cr-NiNbN25-20 Steel After Long-Term Exposure Time at 700 °C

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F26722445%3A_____%2F20%3AN0000217" target="_blank" >RIV/26722445:_____/20:N0000217 - isvavai.cz</a>

Result on the web

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DOI - Digital Object Identifier

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Result language

angličtina

Original language name

Impact of Critical Average Size of Second Phases on Microstructure Stability in Homogeneous Weld Joint Made of X6Cr-NiNbN25-20 Steel After Long-Term Exposure Time at 700 °C

Original language description

The components of the newly built blocks of fossil fuel power plants with A-USC steam parameters in the working interval of 700 °C and 38 MPa are exposed to considerable creep damage. These components are superheating, and reheating piping systems located directly in the fuel space. Is investigated exploitation of new steel grades with higher material properties. In the area of austenitic steels, the perspective grade is undoubtedly HR3C steel (X6CrNiNbN 25-20). In terms of the use of similar weld joints made of HR3C steel in fossil fuel power plants, detailed knowledge on microstructural stability of these weld joints is necessarily. Production technology of homogeneous weld joints made of HR3C steel tubes were using a combination of GTAW and SMAW welding technologies. Weld joints were studied in both the as-welded state (PW), and after post-weld heat treatment (PWHT) at 1230 °C for 15 minutes. The paper presents the results of microstructure investigation on cross-weld samples tested at 650 and 700 °C. Metallographic analysis was performed on longitudinal sections of creep ruptured samples, microstructures of the same areas, states of heat-treatment and different conditions are compared and microhardness HV 0.5 profiles over cross-weld samples were determined. The paper analyses the preferential rupture locations of the HR3C similar weld joints in dependence on the temperature of creep exposure and applied stress. Presented at Mat Science 2020.

Czech name

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Czech description

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Type

O - Miscellaneous

CEP classification

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OECD FORD branch

20501 - Materials engineering

Project

<a href="/en/project/TK03020055" target="_blank" >TK03020055: Research of creep behavior and verification of brittle-fracture properties of austenitic steels for blocks of thermal power plants with USC steam parameters.</a><br>

Continuities

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

Publication year

2020

Confidentiality

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