Influence of severe plastic deformation and subsequent annealing on creep behaviour of martensitic 9% Cr steel

0576256 - ÚFM 2025 RIV CZ eng C - Konferenční příspěvek (zahraniční konf.)
Král, Petr - Dvořák, Jiří - Sklenička, Václav - Horita, Z. - Tokizawa, Y. - Tang, Y. - Kunčická, Lenka - Kuchařová, Květa - Kvapilová, Marie - Svobodová, M.
Influence of severe plastic deformation and subsequent annealing on creep behaviour of martensitic 9% Cr steel.
METAL 2021. 30th Anniversary International Conference on Metallurgy and Materials. Conference proceedings. Ostrava: TANGER, 2021, s. 429-434. ISBN 978-80-87294-99-4. ISSN 2694-9296.
[Metal 2021 - International Conference on Metallurgy and Materials /30./. Brno (CZ), 26.05.2021-28.05.2021]
Grant CEP: GA ČR(CZ) GA19-18725S
Institucionální podpora: RVO:68081723
Klíčová slova: Creep-resistant 9 %Cr steels * severe plastic deformation * creep * microstructure
Obor OECD: Materials engineering

The objective of the study is to evaluate the effects of severe plastic deformation (SPD) and annealing on creep behaviour of advanced tungsten modified creep-resistant 9 % Cr martensitic P92 steel. The as-received P92 steel was deformed by high-pressure torsion (HTP), high-pressure sliding (HPS) and rotary swaging (RS) at room temperature prior creep testing. These SPD methods imposed significantly different equivalent plastic strain in the range from 1 up to 20. Constant load creep tests in tension were performed in an argon atmosphere at 873 K and applied stress ranging from 50 to 200 MPa. The microstructure and phase composition of P92 steel were studied using a scanning electron microscope Tescan Lyra 3 and a transmission electron microscope Jeol 2100F. The results show that under the same creep loading conditions the HPT and HPS-processed P92 steel exhibited significantly faster minimum creep rates, creep fracture strain and the decrease in the value of the stress exponent of the creep rate in comparison with as-received P92 steel. However, it was revealed that the RS-processed specimens exhibited one order of magnitude lower minimum creep rate and lower ductility compared to commercial P92 steel. The creep curves for the HPT and HPS-processed states exhibited a pronounced minimum of strain rate. The pronounced minimum of strain rate disappeared when these states were annealed at 923K/500h before application of creep loading. The microstructure changes occurring during creep and different creep behaviour between as-received and deformed states are discussed.
Trvalý link: https://hdl.handle.net/11104/0345965