DEGRADATION OF CZECHOSLOVAK CREEP RESISTANT STEELS AFTER 50 YEARS OF SERVICE

Ladislav Horváth, Jindřich Douda, Jakub Horváth, Marie Svobodová

Abstract


Thermally loaded assemblies in the energy and chemical industries require materials that provide the necessary functional characteristics, even after very long periods of operation. For the assessment of these materials are used expression grade of degradation in the basic meaning of the original English word grade = quality grade, Where the degradation is cumulative deterioration of quality (properties) and thereby reduce the utility value. Knowledge of these mechanisms acting simultaneously allows determining the boundary conditions and more efficient utilization of used materials. Alternatively, it may give information to a qualified estimate of the causes of failure. Degradation starts its own production of semi-finished products (purity, structural homogeneity) continues through technological factors of production (welding) and the last part of degradation is during service of the parts (corrosion, hydrogen embrittlement, etc.).

The aim of this article is at bases information obtained from fifty years of degraded materials to obtain information for more accurate reference catalogue. This catalogue can on bases information obtained from the microstructure and hardness estimate the state of degradation or possible time to rupture for the material.

Keywords


long-term exposure, boilers, carbon steel, ČSN 41 2022, ČSN 41 3123

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References


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Copyright (c) 2014 Ladislav Horváth, Jindřich Douda, Jakub Horváth, Marie Svobodová

License URL: http://creativecommons.org/licenses/by-nc-nd/3.0/

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