Effects of pre-creep on dislocation and tensile property of Cr-Ni steel

Pre-creep experiments were performed on chromium-nickel (Cr-Ni) stainless steel in the early stage of creep. The temperature was held for 500–2000 h under high-temperature load conditions (873 K and 150 MPa), and various analysis methods, including optical microscopy, electron backscatter diffractio...

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Bibliographic Details
Published in:Materials research express 2021-01, Vol.8 (1), p.16512
Main Authors: Pei, Hai-Xiang, Yang, Xiao-Min, Fang, Xu-Dong, Zhao, Yu-Hong, Huo, Hua
Format: Article
Language:English
Subjects:
Cr-Ni steels
Diffraction patterns
dislocation
Dislocation mobility
Dislocation pinning
Edge dislocations
Electron backscatter diffraction
Grain boundaries
High temperature
Microscopy
Nickel chromium steels
Optical microscopy
Pre-creep
Quadrilaterals
Room temperature
Stainless steels
Tensile tests
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Summary:Pre-creep experiments were performed on chromium-nickel (Cr-Ni) stainless steel in the early stage of creep. The temperature was held for 500–2000 h under high-temperature load conditions (873 K and 150 MPa), and various analysis methods, including optical microscopy, electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), and X-ray diffraction, were used to determine the pattern of dislocation evolution under different temperature-holding times. The results showed that the slip bands intersected at the initial stage of pre-creep, and a quadrilateral network structure was formed by the dislocation pinning. As the temperature-holding time increased, the dislocation network began to climb to form dislocation walls, dislocation cells, and other substructures. At 2000 h, the grain boundaries widened considerably; creep holes were found at the grain boundaries; and dislocation pairs with oscillating contrast occurred, which indicates nitrogen diffusion. The yield and tensile strengths of the Cr-Ni steel samples subjected to pre-creep at holding times of above 1000 h decreased after they were subjected to room-temperature tensile tests.
ISSN:2053-1591
2053-1591
DOI:10.1088/2053-1591/abd420