Effects of Finish Rolling Temperature on the Critical Crack Tip Opening Displacement (CTOD) of Typical 500 MPa Grade Weathering Steel

In this study, the effect of finish rolling temperature on the critical crack tip opening displacement (CTOD) of typical 500 MPa grade weathering steel was elucidated. The microstructures were observed via optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope...

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Bibliographic Details
Published in:Metals (Basel ) 2023-10, Vol.13 (10), p.1791
Main Authors: Wu, Junping, Bai, Guangming, Zhao, Liyang, Zhang, Zhongde, Peng, Yan, Chu, Juefei, Wang, Qingfeng
Format: Article
Language:English
Subjects:
Atmospheric corrosion
Cooling
Corrosion resistant steels
Crack opening displacement
Crack tips
critical crack tip opening displacement
Cryogenic properties
Electron back scatter
Ferrite
Finish rolling
finish rolling temperature
Fracture toughness
Grain boundaries
high angle grain boundary
Iron compounds
Iron constituents
M/A constituents
Martensite
Microstructure
Morphology
Optical microscopes
Phase transitions
Scanning electron microscopy
Structural steels
Temperature
Tensile strength
Transmission electron microscopes
weathering steel
Weathering steels
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Summary:In this study, the effect of finish rolling temperature on the critical crack tip opening displacement (CTOD) of typical 500 MPa grade weathering steel was elucidated. The microstructures were observed via optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM), and electron back-scattered diffraction (EBSD). The cryogenic fracture toughness and microstructures of steels were analyzed at different finish rolling temperatures (780–840 °C). The results show that a mixed microstructure, i.e., granular bainitic ferrite (GBF), polygonal ferrite (PF), and martensite/austenite (M/A), constituent was formed in each sample. With the decrease of the finish rolling temperature, the GBF content decreased, PF content increased, and the high angle grain boundary (HAGB) number fraction of the matrix increased. Furthermore, the fraction of M/A constituents was increased with reduced average size. The value of CTOD increased significantly from 0.28 to 1.12 mm as the finish rolling temperature decreased from 840 to 780 °C. Both the decrease of M/A constituents and the increase of HAGB increased the cryogenic (−40 °C) fracture toughness of the typical 500 MPa grade weathering steel.
ISSN:2075-4701
2075-4701
DOI:10.3390/met13101791