A simulation method based on simplified arc model is developed for the analysis of GMAW deposition with various external magnetic fields. The electromagnetic force distributions in the workpiece produced by longitudinal and transversal magnetic fields are systematically investigated in comparison with the case without external field. The results reveal that the inherent electromagnetic force of GMAW welding drive the converging and sinking flow in the central of melt pool. The external longitudinal field results in circumferential electromagnet...