Temperature field simulation and asymmetric heat transfer distribution of dissimilar steel welded with external transverse magnetic field

Abstract

During the welding process of Q235 mild steel to 304 L stainless steel, the difference in their thermal properties and magnetic permeability deflects the arc to the mild steel side, resulting in unstable welding process, poor weld formation, and reduced penetration depth. In this paper, a method of applying an external transverse magnetic field acting on the welding arc is proposed to overcome the adverse effects of arc deflection. The experimental results show that the welding depth of Q235/304 L can be significantly improved by magnetically controlled arc welding process. In order to understand the asymmetric heat transfer distribution of dissimilar steel under the action of external transverse magnetic field, a new type of deflection heat source was constructed. The influence of transverse magnetic field deflection arc on heat source parameters was considered, and the welding temperature field of Q235/304 L was simulated to study the welding temperature field of dissimilar steel under the action of magnetic field. In the error analysis, the maximum error of the deflected heat source model is less than 16 %, and the average error is less than 7 %. Compared with the asymmetric heat source model, the constructed heat source model is more accurate in calculation. The depth of melt and temperature variation around the weld under different excitation currents were studied. The weld forming and welding heat transfer law of dissimilar steel with external transverse magnetic field are obtained, which could be used to further improve the welding quality of dissimilar steel.