To investigate the physical mechanisms of weld pool on selected sub-level regions, a new technique to be used in coupling digital microstructure codes with finite element codes is proposed. The strategy flexible to be implemented to any number of levels is used to mesh a local part of the model with a refined mesh based on interpolation of the solution from an initial, relatively coarse, global model. The meso sub-model is the global model for the subsequent mi- cro sub-model. The multi-scale submodeling approach can be used to capture weld pool features at the macro-meso scale level, and micro residual stress and secondary dendrite arm spacing features at the micro scale level. With this technique, initiation and propagation of cracks in metal welded specimens, beginning at the microstructural length scale, can also be investigated.