Micromechanical Fracture Models of Q345 Steel and Its Weld
Publication: Journal of Materials in Civil Engineering
Volume 31, Issue 11
Abstract
To better predict the ductile fracture of welded joints in steel bridges and buildings under seismic load, the fracture behavior of Q345 steel that has been widely used in China was studied under both monotonic and cyclic loadings based on the microscopic mechanism of material fracture. Based on the results of notched round bar tensile tests and finite-element analyses for Q345 steel base metal, weld metal (transverse and longitudinal), and heat-affected zone specimens, the parameters of the void growth model, stress-modified critical strain model, and cyclic void growth model were calibrated. The parameters of characteristic length in the previous models were determined by scanning electron microscope tests. The results indicated that the toughness parameters of the four materials are significantly different, and the cyclic growth capacity of the voids in weld metal and heat-affected zones deteriorates severely under cyclic loading. The toughness parameters of the two oriented weld metals are similar; therefore, the fracture toughness of the weld metal is less affected by the material orientation. The coefficients of variation of the toughness parameters of the four materials were small, and the distributions of the fracture indexes of the specimens with different notch radii were the same, which proved the effectiveness of the microscopic mechanism fracture model in predicting the initiation of ductile cracks of the members with different geometric shapes and stress states. The results of this paper provide the required material data and model parameters to predict the ductile fracture of welded joints made of Q345 steel using existing micromechanical fracture models.
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Data Availability Statement
Some or all data, models, or code generated or used during the study are available from the corresponding author by request.
Acknowledgments
This research is funded by the National Natural Science Foundation of China (NSFC) (Grants Nos. 51421005 and 51578022). This support is gratefully acknowledged. The results and conclusions presented in the paper are those of the authors and do not necessarily reflect the view of the sponsors.
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Published In
Journal of Materials in Civil Engineering
Volume 31 • Issue 11 • November 2019
Copyright
©2019 American Society of Civil Engineers.
History
Received: May 20, 2018
Accepted: May 29, 2019
Published online: Aug 26, 2019
Published in print: Nov 1, 2019
Discussion open until: Jan 26, 2020
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