DUCTILE FRACTURE BEHAVIOR OF WELD METAL FOR Q345 STEEL UNDER MONOTONIC LOADING

To study the ductile fracture behavior of weld metal for Q345 steel, nine specimens with different distribution of stress triaxiality and Lode angle were tested under monotonic loading. Swift, Voce and mixed swift-voce hardening models were used to fit the full stress-strain curves up to fracture. in comparison, the mixed Swift-Voce hardening model showed the best accuracy in simulating the load-displacement curves of the specimens. In addition, three kinds of fracture prediction models, namely, VGM, modified SWDM and Lou models, were utilized. The material parameters were calibrated by the UVARM subroutine and applied to the finite element numerical simulations. The accuracy of these prediction models were compared and analyzed. The results showed that the VGM model presented a relatively large error in predicting the fracture of rectangular notches and grooved plate specimens when they were near the plane strain state. However, the modified SWDM and Lou models produced accurate predictions when the Lode angle were considered to describe the deviatoric stress state. Based on the fracture prediction results, the modified SWDM and Lou models were effective for specimens of various stress states.