Characterisation of properties and microstructural changes of 12% Cr-W steels after long-term service

• Autorzy: Hernas A. , Moskal G. , Rodak K. , Pasternak J.
• Języki publikacji: EN

Abstrakty

EN

Purpose: Characterization of the influence of long-term exposition on microstructural stability and properties of new modified ferritic steels containing 12% Cr with W addition. Design/methodology/approach: The examinations were made on samples from superheater tubes (HCM12 and HCM12A type of steel) after long term exposition (20 and 30 thousand hours). The major technique used to investigations are: microstructural analysis with the use of LM, SEM and TEM and measurement of hardness and strength at an ambient temperature and at 600° C. Findings: Investigated power plant steels exhibit high stability of microstructeres and mechanical properties. The main effects of degradation are related to the decomposition of martensite areas, the precipitation of M23C6 carbides and Laves' phases, and the processes of recrystallization and recovery. Results of mechanical examinations showed that main mechanical parameters was still satisfactory after 30.000 hours of operation. Research limitations/implications: Presented examination showed that new type of power plant steels are characterized by high stability of the microstructure and properties, however it necessary to identify the mechanisms of structure degradation and, in consequence, of adjusting the mechanical properties below the values required. It is therefore necessary to continue the investigations after successive periods of operation. Practical implications: Presented conclusion give the possibility to the determination of the degree of life-time lost of the investigated high-chromium steels and specification of the time of safety operation. Originality/value: This investigations are valuable contribution to the development of new steels for the power industry. They enable the identification of the degradation mechanisms in steels of new types, which enhances the durability and safety of boilers' operation.

Słowa kluczowe

EN

residual life analysis; electron microscopy; metallic alloys

• Wydawca: International OCSCO World Press
• Czasopismo: Journal of Achievements in Materials and Manufacturing Engineering
• Rocznik: 2008
• Tom: Vol. 31, nr 2
• Strony: 312--319
• Opis fizyczny: Bibliogr. 15 poz., wykr.

Twórcy

autor

Hernas A.

autor

Moskal G.

autor

Rodak K.

autor

Pasternak J.

• Materials Science Department, Silesian University of Technology, ul. Krasińskiego 8, 40-019 Katowice, Poland,

Bibliografia

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