The Effect of Ultrafine-Grained Microstructure on Creep Behaviour of 9% Cr Steel

0491887 - ÚFM 2019 RIV CH eng J - Journal Article
Král, Petr - Dvořák, Jiří - Sklenička, Václav - Masuda, T. - Horita, Z. - Kuchařová, Květa - Kvapilová, Marie - Svobodová, M.
The Effect of Ultrafine-Grained Microstructure on Creep Behaviour of 9% Cr Steel.
Materials. Roč. 11, č. 5 (2018), č. článku 787. E-ISSN 1996-1944
R&D Projects: GA ČR(CZ) GA16-09518S
Institutional support: RVO:68081723
Keywords : high-pressure torsion * severe plastic-deformation * martensite ferritic steels * fe2w laves phase * long-term creep * strengthening mechanisms * precipitation behavior * resistant steels * room-temperature * 9cr steels * creep-resistant 9% Cr steels * ultrafine grained materials * creep * electron back scatter diffraction
OECD category: Materials engineering
Impact factor: 2.972, year: 2018

The effect of ultrafine-grained size on creep behaviour was investigated in P92 steel. Ultrafine-grained steel was prepared by one revolution of high-pressure torsion at room temperature. Creep tensile tests were performed at 873 K under the initially-applied stress range between 50 and 160 MPa. The microstructure was investigated using transmission electron microscopy and scanning electron microscopy equipped with an electron-back scatter detector. It was found that ultrafine-grained steel exhibits significantly faster minimum creep rates, and there was a decrease in the value of the stress exponent in comparison with coarse-grained P92 steel. Creep results also showed an abrupt decrease in the creep rate over time during the primary stage. The abrupt deceleration of the creep rate during the primary stage was shifted, with decreasing applied stress with longer creep times. The change in the decline of the creep rate during the primary stage was probably related to the enhanced precipitation of the Laves phase in the ultrafine-grained microstructure.
Permanent Link: http://hdl.handle.net/11104/0286827