Combination of Experiments and Continuum Damage Mechanics Approach for Prediction of Creep Fracture in an Advanced 9%Cr Steel

0470524 - ÚFM 2018 RIV CH eng C - Conference Paper (international conference)
Sklenička, Václav - Kuchařová, Květa - Kvapilová, Marie - Král, Petr - Dvořák, Jiří
Combination of Experiments and Continuum Damage Mechanics Approach for Prediction of Creep Fracture in an Advanced 9%Cr Steel.
Materials Structure & Micromechanics of Fracture VIII. Zürrich: Trans Tech Publications, 2017 - (Šandera, P.), s. 591-594. Solid State Phenomena, 258. ISBN 978-3-03835-626-4. ISSN 1662-9779.
[MSMF8. International Conference on Materials Structure and Micromechanics of Fracture /8./. Brno (CZ), 27.06.2016-29.06.2016]
R&D Projects: GA ČR(CZ) GA16-09518S
Institutional support: RVO:68081723
Keywords : steel P92 * high-temperature fracture * creep fracture mode * creep cavitation * creep damage tolerance factor
OECD category: Materials engineering

As candidate materials for high-temperature components, most attention has been paid to improving tempered martensitic creep-resistant 9-12%Cr steels. In this work, creep damage and fracture behaviour of an advanced W-modified P92 steel (ASTM Grade P92) was investigated at 600 and 650°C. Tensile creep tests were followed by fractographic analysis of crept and broken specimens. Besides experimental investigations, the creep damage tolerance parameter lambda has been used to assess the creep fracture mode. In accordance with experiments the values of lambda indicate variety in the fracture mode and provide some evidence on accelerated degradation of the creep strength. The SEM investigations of creep fracture surface revealed substantial changes in microfractographic features of creep fracture. At high applied stress level, the fracture was frequently transgranular due to local loss of a stability of plastic deformation. The fracture ductility drops with decreasing applied stress, demonstrating ductile dimple (transgranular) to brittle (intergranular cavitation) transition of the fracture mode. It was suggested that both the creep deformation and fracture processes are controlled by the same processes and the rate controlling mechanism is most probably climb of intergranular mobile dislocations.
Permanent Link: http://hdl.handle.net/11104/0271298