Properties and microstructure of 12% Cr-W steels after long-term service

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

Abstrakty

EN

Purpose: The purpose of the research was to identify the influence of long-term exposition on stability of the microstructure and properties of new ferritic steels containing 12% Cr with W addition. Design/methodology/approach: The research allowed the identification of microstructural changes that takeplace during long-term operation and their influence on the mechanical properties. The examinations wereconducted on superheater tubes (HCM12 and HCM12A steel) after 20 and 30 thousand hours of exposition. The scope of the research encompassed a microstructural analysis with the use of LM, SEM and TEM andmeasurement of hardness and strength at an ambient temperature and at 600oC. Findings: It was found that the steels showed high stability of structures and mechanical properties. The mainsymptoms of degradation are connected with the decomposition of martensite areas, the precipitation of M23C6 carbides and Laves’ phases, and the processes of recrystallization and recovery. The level of all mechanical parameters was still satisfactory after 30,000 hours of operation. Research limitations/implications: The discussed research proves high stability of the microstructure and properties of the investigated steels, 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: The results obtained allow 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: The results obtained 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

metallic alloys; research methodology; electron microscopy; residual life analysis

PL

stopy metali; metodologia badań; mikroskopia elektronowa; analiza trwałości resztkowej

• Wydawca: International OCSCO World Press
• Czasopismo: Journal of Achievements in Materials and Manufacturing Engineering
• Rocznik: 2006
• Tom: Vol. 17, nr 1-2
• Strony: 69--72
• Opis fizyczny: Bibliogr. 15 poz., rys., tab.

Twórcy

autor

Hernas A.

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

autor

Moskal G.

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

autor

Rodak K.

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

autor

Pasternak J.

• Boiler Engineering Factory RAFAKO S.A., ul. Łąkowa 33, 47-400, Racibórz, Poland

Bibliografia

• [1] R. Viswanathan, W. T. Bakker, Materials For Boilers In Ultra Supercritical Power Plants, Proceedings of 2000 International Joint Power Generation Conference Miami Beach, Florida, July 23-26, 2000, IJPGC2000-15049.
• [2] T. Fujita, Current Progress in advanced high Cr ferritic steels for high-tmperature applications, ISIJ International, Vol. 32, 1992, No. 2, pp. 175-181.
• [3] F. Masuyama et al., Development and applications of a high-strength 12% Cr steel tubing with improvement weldability, Mitsubishi Heavy Industries Ltd., Technical Review, Oct. 1986, pp. 229-237.
• [4] R.D. Hottenstine, N.A. Phillips and R.A. Dill, Development Plans for Advanced Fossil Fuel Power Plants, Report CS4029, EPRI, Palo Alto, 1985.
• [5] M. Gold and R.I. Jaffee, Materials for Advanced Steam Cycles, ASM J. of Materials for Energy Systems, Vol. 6 (No. 2), 1984, p. 130-145.
• [6] D.V. Thornton and K.H. Meyer, European High Temperature Materials Development. in Advanced Heat Resistant Steels for Power Generation, R. Viswanathan and J.W. Nutting, Ed.; IOM Communications Ltd., London, pp. 349-365, 1999.
• [7] R. Viswanathan and W.T. Bakker, Materials for Ultra Supercritical Fossil Power Plants, Report TR-114750, EPRI, Palo Alto, January 2000.
• [8] W.T. Bakker, Materials for Advanced Boilers., in Advanced Heat Resistant Steels for Power Generation, R. Viswanathan and J.W. Nutting, Ed.; IOM Communications Ltd., London, pp 435-455, 1999.
• [9] F. Masuyama, New Developments in Steels for Power Generation Boilers, in Advanced Heat Resistant Steels for Power Generation, R. Viswanathan and J.W. Nutting, Ed.; IOM Communications Ltd., London, pp. 33-48, 1999.
• [10] J. Pasternak, A. Hernas, P. Miliński, New martensitic steels for super critical boilers, Energetyka, No 4, 1997, (in Polish).
• [11] J. Pasternak, A. Kiełbus, Stability of similar and dissimilar welded joints, high temperature creep resistant martensitic steel containing 9% Cr, Proceedings of the EPRI Fourth International Conference of Advances in Materials Technology for Fossil Power Plants, October, 25-26, 2004.
• [12] W. Garrison and R.F. Buck, An Overview of the Development of Advanced 9-12% Cr Steels, In ASM Symposium on Materials for Rotating Machinery, Oct 1999, Cincinnati.
• [13] K.H. Mayer et al., New Materials for Improving the Efficiency of Fossil-fired Thermal Power Stations, International Joint Power Generation Conference, PWR-Vol. 33, ASME, 1998, pp 831-841.
• [14] T. Topoda et al., Development of Thick Walled Pipes and Headers of Modified 9Cr Steel., Proc. of the Second International Conference on Improved Coal-fired Power Plants, 2-7 Nov. 1988, Palo Alto, CA, EPRI Report GS-6422, pp. 36-1.
• [15] A. Iseda et al., Development of new 12%Cr steel tubing (HCM12) for boiler application, The Sumitomo Search, No. 40, Nov. 1999, pp. 41-56.