Crystal Plasticity Model Analysis for the Macro-to-Micro Mechanical Behavior of Different Sub-Regions in a Marine Steel Weld

The present study investigates the macro-to-micro inhomogeneous mechanical behavior of different sub-regions in a 64-mm-thick marine steel weld, using an optical microscope, electron backscatter diffraction, micro-tensile test, and numerical simulation of a crystal plasticity model. The results show that the tensile properties of the different micro-regions of the weld show great differences, with the lowest tensile strength in the intracrystalline polygonal ferrite region at the root of the weld and the highest tensile strength in the intracrystalline acicular ferrite region. The results of the crystal plasticity model demonstrate that the different micro-regions of the welded joint produce similar stress-deformation situations when subjected to loads. Stress concentrations appear in the dense region of fine grain boundaries, but the stress concentration is not the only condition for cracks to occur. The crack emergence and propagation are strongly influenced by the inhomogeneous organization, and cracks tend to arise at the intersection of stress concentrations and multiple grain boundaries, and expand outward along the grain boundaries. In the weld, the grain bound ferrite (region is more likely to occur damage.