Mass, Momentum, and Energy Transport in a Molten Pool When Welding Dissimilar Metals

Velocity and temperature fields, and shapes of the fusion zone in welding dissimilar metals are systematically investigated. Fluid flow in the molten pool is driven by the Marangoni force in different directions and magnitudes on the flat free surface. To interpret clearly without loss of generality, the three-dimensional quasi-steady welding is simulated by an unsteady two-dimensional process. Transport process on the maximum cross section of the molten region (or a cross section of the fusion zone) therefore is predicted. Interfaces between immiscible dissimilar metals and solid and liquid are, respectively, calculated by the volume of fluid and enthalpy methods. The computed results show different flow and thermal fields and molten regions of dissimilar metals as functions of dimensionless surface tension coefficients, viscosities, melting temperatures, and thermal conductivities of dissimilar metals and distinct phases, and beam power, welding speed, and the energy distribution parameter. The predicted shapes of fusion zones in welding pure irons, and aluminum to iron, agree with the experimental results.