Abstract
Elastic-plastic two-dimensional (2D) and three-dimensional (3D) finite element models (FEM) are used to analyze the stress distributions ahead of notches of four-point bending (4PB) and three-point bending (3PB) specimens with various sizes of a C-Mn steel. By accurately measuring the location of the cleavage initiation sites, the local cleavage fracture stress σf and the macroscopic cleavage fracture stress σF is accurately measured. The σf and σF measured by 2D FEM are higher than that by 3D FEM. σf values are lower than the σF, and the σf values could be predicted by σf=(0.8−−1.0)σF. With increasing specimen sizes (W,B and a) and specimen widths (B) and changing loading methods (4PB and 3PB), the fracture load P f changes considerably, but the σF and σf remain nearly constant. The stable lower boundary σF and σf values could be obtained by using notched specimens with sizes larger than the Griffiths–Owen specimen. The local cleavage fracture stress σf could be accurately used in the analysis of fracture micromechanism, and to characterize intrinsic toughness of steel. The macroscopic cleavage fracture stress σF is suggested to be a potential engineering parameter which can be used to assess fracture toughness of steel and to design engineering structure.
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Wang, G., Chen, J. & Wang, J. On the measurement and physical meaning of the cleavage fracture stress in steel. International Journal of Fracture 118, 211–227 (2002). https://doi.org/10.1023/A:1022908402233
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DOI: https://doi.org/10.1023/A:1022908402233