Theoretically more accurate magnetic method to calculate arc welding process

Abstract

Self-induced magnetic field has an important impact on thermal plasma properties as it compresses the plasma arc through magnetic force. Accurate calculation of the magnetic field is thus necessary in arc welding models. Magnetic potential approach (PM) and Ampère–Maxwell circumfluence formulation (AM) are the two methods in previous research. However, PM requires hypothetical magnetic potentials on boundaries since they are unknown, while AM is a simplified model. Therefore, a theoretically more accurate method named mixed PM and Biot–Savart law (MM) was applied to calculate the magnetic field. Biot–Savart law was first used to supply accurate magnetic potentials on boundaries rather than by hypothetical values in previous research. Then, PM was applied to predict the magnetic field with the more accurate boundary conditions. Comparisons of temperature field, flow field, and electromagnetic field predicted by the new method and the other two methods were shown in the paper. AM predicts the highest magnetic induction intensity and magnetic force, which leads to the maximum arc velocity, heat flux, and arc pressure. MM gives the lowest heat flux and arc pressure since it has the lowest arc velocity. PM almost gives zero magnetic induction intensity on the boundary of the nozzle due to the inaccurate pre-supposed boundary conditions. Welding experiment validates that MM has the highest precision in calculating the weld pool geometry and arc pressure.