HEAT TRANSFER AND FLUID FLOW IN LASER MELTED WELD POOLS.

A mathematical model was developed for the calculation of heat transfer and fluid flow in laser melted pools. Appropriate equations of change were solved numerically to obtain insight into the significance of various welding parameters. Furthermore, the model was used to examine the role of sulfur in determining the pool shape during laser welding. The weld pool temperature obtained from vapor composition was in reasonable agreement with the predicted temperature values. From the analysis of the numerically predicted flow fields it was demonstrated that the heat transfer from the laser beam to the base metal via the molten weld pool was significantly improved by the presence of an appropriate surface active agent. Critical experiments were designed and conducted to determine the weld pool shapes with samples of pure iron and iron doped with sulfur. The pool shapes predicted by the model were found to be in good agreement with those obtained experimentally.