NUMERICAL ANALYSIS OF HEAT TRANSFER AND FLUID FLOW IN MICRO-WELDING USING CFD

摘要

Laser welding is used to join metals of small thickness. The heat affected zone in this process is very small and the temperature gradients encountered are very large (of the order of 10~4K/mm). We have used numerical methods to analyze the effect of various parameters. For the present study, an in-house C code was developed to model the laser welding process. A Finite Volume based discretization was done and a Semi-Explicit method was used to solve the governing equations. Conduction mode heat transfer was considered by assuming no vaporization of the molten metal. The effect of various parameters like beam intensity and beam radius were studied on the weld dimensions. The beam intensity was varied from 5.2KW to 15K.W while the beam radius was varied from 0.14mm to 0.35mm. The effect of welding angle was also studied on the weld dimensions. The welding angles used for the study were 0°, 26.5°, 45° and 56°. It was found that the weld width and depth increased with an increase in beam intensity and a decrease in beam radius, while the weld depth decreased with an increase in welding angle. The change in heat transfer and fluid flow was also studied by varying these parameters.