HEAT-TRANSFER IN A STUD-TO-PLATE LASER BRAZE CONSIDERING FILLER METALMOVEMENT

A finite element model has been developed for the thermal analysis of a miniature stud-to-plate laser brazing process, and the transient tem perature fields in the braze joint were analyzed by using an axisymmet ric model. The finite element program ABAQUS, together with a few user subroutines; were employed to perform the numerical approximation. Th e joining materials used were AISI 304 stainless steel and Al 5052 alu minum, and the alloy 88Al-12Si for the braze filler metal. Nonlinear e ffect of temperature dependent thermal properties, latent heat and the convection and radiative heat losses were considered. The FE modeling was implemented with a non-coupled treatment of heat conduction and f iller metal flow, while the model was based upon the real-time motion analysis of the brazing process. Definition of the. FE solution domain and boundary conditions were crucial to achieve accuracy in predictin g the transient thermal behavior, possible only with the aid of a high -speed camera. Numerical results of the temperature fields in the braz e joint were obtained for typical process parameters. The predicted th ermal histories show a fairly good agreement with the experimental one s that were determined by using the thermocouple and infrared temperat ure measurements.