The Effect of Predeformation on Creep Strength of 9% Cr Steel
Petr Král,
Jiří Dvořák,
Wolfgang Blum,
Václav Sklenička,
Zenji Horita,
Yoichi Takizawa,
Yongpeng Tang,
Lenka Kunčická,
Radim Kocich,
Marie Kvapilová,
Marie Svobodová
Affiliations
Petr Král
Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Zizkova 22, 616 62 Brno, Czech Republic
Jiří Dvořák
Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Zizkova 22, 616 62 Brno, Czech Republic
Wolfgang Blum
Department of Materials Science, Institute I, University of Erlangen-Nuremberg, D-91058 Erlangen, Germany
Václav Sklenička
Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Zizkova 22, 616 62 Brno, Czech Republic
Zenji Horita
Department of Materials Science, Kyushu Institute of Technology, Kitakyushu 804-8550, Japan
Yoichi Takizawa
Technology Department, Nagano Forging Co., Ltd., Nagano 381-0003, Japan
Yongpeng Tang
World Premier International Research Initiative, International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Fukuoka 819-0395, Japan
Lenka Kunčická
Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Zizkova 22, 616 62 Brno, Czech Republic
Radim Kocich
Faculty of Materials Science and Technology, Technical University of Ostrava, 17. Listopadu 15, 708 00 Ostrava, Czech Republic
Marie Kvapilová
Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Zizkova 22, 616 62 Brno, Czech Republic
Marie Svobodová
UJP PRAHA a.s., 156 10 Praha-Zbraslav, Czech Republic
Martensitic creep-resistant P92 steel was deformed by different methods of severe plastic deformation such as rotation swaging, high-pressure sliding, and high-pressure torsion at room temperature. These methods imposed significantly different equivalent plastic strains of about 1–30. It was found that rotation swaging led to formation of heterogeneous microstructures with elongated grains where low-angle grain boundaries predominated. Other methods led to formation of ultrafine-grained (UFG) microstructures with high frequency of high-angle grain boundaries. Constant load tensile creep tests at 873 K and initial stresses in the range of 50 to 300 MPa revealed that the specimens processed by rotation swaging exhibited one order of magnitude lower minimum creep rate compared to standard P92 steel. By contrast, UFG P92 steel is significantly softer than standard P92 steel, but differences in their strengths decrease with increasing stress. Microstructural results suggest that creep behavior of P92 steel processed by severe plastic deformation is influenced by the frequency of high-angle grain boundaries and grain coarsening during creep.