Microstructure and mechanical properties of the T23 steel after long-term ageing at elevated temperature

Changes In Properties and Microstructure of High-Chromium 9-12%Cr Steels Due to Long-Term Exposure at Elevated Temperature

“…The insignificant disappearance of tempered martensite microstructure was also observed. After annealing at 650°C for 30,000 h, there was an significant increase in the size of precipitates at the prior austenite grain boundaries, at the martensite lath boundaries and inside grains compared to, not only the as-received condition of VM12 steel, but also in relation to the same time of annealing at 600°C [7]. A partial disappearance of the tempered lath martensite microstructure is also visible (Fig.…”

“…The chromium content at the level of 9% in P91 and P92 steels restricts their use up to a temperature of 580-600°C. Also, the carbon content in 9% Cr steels affects the type of existing precipitations and the form of martensite, which is described in great detail, inter alia, in [7,[9][10][11]. Higher chromium content of 12% in VM12 steel is required to ensure the oxidation and gas corrosion resistance during the operation at above 600°C [7].…”

“…The basic requirements placed on all creep-resisting steels are that they should maintain, for a long time, the assumed mechanical properties, high-temperature creep resistance and heat resistance as the elements of safe (reliable) operation within the design working parameters of boiler [1][2][3][4][5][6][7][8].…”

“…In cooperation with other research centres (Silesian University of Technology, Czestochowa University of Technology, AGH University of Science and Technology in Cracow) as well as the boiler factories Rafako S.A. and SEFKAO S.A. -the leading manufacturers of boilers, the Institute for Ferrous Metallurgy performs the works on the advance and verification testing of new-generation steels for the power industry [2,7,8,19,21,23].…”

“…In safety assessment of the pressure equipment in which new creep-resisting steels were used, it is essential that a number of tests should be carried out to allow the evaluation of their condition and suitability for further operation beyond the design work time under further operation conditions [7,8,[12][13][14][15][16][17][18][19].…”