values of fracture mechanics parameter were experimentally and numerically obtained for specimens with a pre-crack in HAZ and WM. Numerical analysis of elastic-plastic finite element models (2D and 3D) was performed in software package Abaqus, with micromechanical complete Gurson model (CGM) applied through user subroutine, UMAT (author: Z.L. Zhang). The crack tip constraint and variation of stress triaxiality in ligament were numerically analyzed on single-edge notched bend and tensile specimens to analyze the transferability of micromechanical damage parameters from one specimen to another. In addition, the geometry effects were also studied by the micromechanical approach and the results were compared with those of the experiments. Most of numerical results obtained with CGM model are in good agreement with the experimental results. Analysis of results shows that micromechanical approach is reliable technique to describe ductile fracture behavior in high strength steel weldments, including the effect of constraints and heterogeneity. It was also observed that the initiation toughness and the crack growth resistance are greatly affected by the mechanical heterogeneity of the weldment and the crack tip constraint. Additionally, the numerical values of the initiation toughness and the crack growth resistance are also affected greatly by the size of finite element. Moreover, micromechanical damage parameters could be transferred from one component to another without depending on constraint effect etc. The results also show that estimation of mechanical properties for various welded regions, especially for narrow HAZ regions, could be considered as alternative technique to the standard one, which may not be applied to estimate their mechanical properties when welded joint is transversally subjected to applied load.

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