Heat and mass transfer in laser dissimilar welding of stainless steel and nickel

Laser spot welding of stainless steel-nickel dissimilar couple has been studied experimentally and numerically. A three-dimensional heat and mass transfer model is used to simulate the welding process, based on the solution of the equations of mass, momentum, energy conservation and solute transport in weld pool. The calculated fusion zone geometry and element distributions are in good agreement with the corresponding experimental results. The role of fluid flow on temperature field and its evolution is analyzed by comparing two cases with and without considering convection. Temperature fields far away from the weld pool are quite similar, but exhibit large difference close to the heat source. During the early stage after formation of weld pool, the distribution of element Fe in weld pool is non-uniform, due to insufficient time for mixing. The speed for mass transport is the highest during the initial stage of weld pool formation and it decreases with time. Both heat and mass transport are significantly influenced by convection during laser spot welding of stainless steel and nickel.